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Item No. 1 of 27

ACCESSION NO: 0164317 SUBFILE: CRIS
PROJ NO: NEB-10-124 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 01 JAN 1994 TERM: 31 DEC 1998 FY: 1999

INVESTIGATOR: Supalla, R. J.; Allen, J. C.

PERFORMING INSTITUTION:
AGRICULTURAL ECONOMICS
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

ECONOMIC ANALYSIS OF FARM MANAGEMENT & PUBLIC POLICY ALTERNATIVES FOR IMPROVING GROUNDWATER QUALITY

OBJECTIVES: Evaluate the farm level consequences of alternative technologies and management practices for reducing groundwater pollution from irrigated agriculture. Analyze the adoption behavior of irrigated products with respect to the use of best mangement practices (BMP's) for improving water quality. Evaluate public policy alternatives for improving groundwater quality.

APPROACH: A systems approach is used to assess the economic and environmental tradeoffs associated with alternative management strategies for reducing nitrate contamination of groundwater. Farm level management alternatives will be evaluated to determine best management practices (BMP's). The types of alternatives to be considered include: crop rotations; amount, timing and method of nitrogen application; amount, timing and method of water applications; and crop monitoring technologies. Public policies for encouraging the adoption of best management practices will also be evaluated, including educational programs, incentives and direct regulations.

NON-TECHNICAL SUMMARY: Nitrate pollution of groundwater is an important environmental problem in Nebraska. This project is focused on finding least cost methods of reducing nitrate pollution of groundwater from irrigated agriculture.

PROGRESS: 1994/01 TO 1998/12
This project addressed management options for reducing nitrate pollution of groundwater, using the Central Platte valley of Nebraska as a case study area. The first major finding was that not all producers were maximizing profits and over 80 percent of producers in the region expressed a willingness to voluntarily incorporate environmental considerations in their production decisions even if it significantly reduced profits. Also, several production practices were identified which if adopted by producers would be win-win, i.e., they would increase profits and improve environmental quality. The presence of a strong environmental ethic among producers and the existence of win-win opportunities was unexpected and suggests that it may be possible to improve environmental quality through education programs without the use of conventional command and control or incentive strategies. Another major finding was that the BMP's for reducing nitrate pollution of groundwater in irrigated regions depended substantially on the current quality of the water. When irrigation water contained less than 15 mg/l of nitrate nitrogen, sprinkler irrigation with minimal water applied was the preferred management option, both economically and environmentally. With high nitrate water, however, the best economic option was well managed gravity irrigation, and the best environmental option was sprinkler irrigation applying more water than what was needed to meet evapotranspiration requirements. Precision farming, or Variable Rate Application Technology (VRAT), was evaluated as a management tool for implementing those BMP's which call for more precise management of the nitrogen and/or water input. Simulation results for several hypothetical fields that consisted of different proportions of three soils (Hord, Valentine and Platte Associations) found that VRAT increased corn yield by 9 to 26 percent, decreased water applied by 1 to 6 percent, decreased nitrogen applied by up to 22 percent and decreased nitrogen leached by up to 44 percent. Economic results suggest that producers could afford to pay from $9 to $26 per acre per year for VRAT technology and still be as well off financially as they would be using conventional practices. Estimates of the elasticity of demand for nitrogen suggest that own price elasticity has fallen from greater than -1.0 to less than -0.2, as producers have become more environmentally concerned and education programs to improve management have intensified. At an elasticity level of -0.2, it wold cost over $1.00 per pound to reduce leaching at the current use level margin. In contrast, the adoption of Best Management Practices (BMP's) was found to reduce nitrate leached at a cost of from less than zero (win-win situation ) to about $0.50 per pound. A contingent valuation and an averting cost study of willingness to pay for improved water quality in Nebraska was also conducted. Contingent valuation results indicated that consumers were willing to pay an average of $9.50 per household per month to reduce nitrate pollution to levels below the public health standard.

IMPACT: 1994/01 TO 1998/12
The primary payoffs from this research are improved water quality and increased economic returns to agriculture. These gains result from the adoption of the improved nitrogen and water management practices. Available evidence for nitrogen management indicates that irrigated producers on the average apply at least 50 pounds per acre of excess N. If only 10 percent of irrigators are induced by this research (and related programs) to reduce excess applied N by only 25 pounds per acre, it would mean an annual reduction in pollution of 10,000 tons of nitrate nitrogen and an increase in net economic returns of $3,000,000 per year.

PUBLICATIONS: 1994/01 TO 1998/12
1. Supalla, R. J., R. A. Selley, S. Bredeweg and D. G. Watts. 1995. "Factors Affecting Adoption of Practices to Improve Water Quality." Journal of Soil and Water Conservation, Jan./Feb.
2. Supalla, R. J., W. M. Miller and B. Julianno. 1996. "Linkages Between Technology Adoption Behavior in Agriculture and Environmental Policy." The Sixth International Symposium on Social and Resource Management, Pennsylvania State University, University Park, PA.
3. Supalla, R. J., S. Ahmad and R. A. Selley. 1996. "Policy Implications of Win-Win Opportunities for Improving Groundwater Quality in Irrigated Areas." Abstract, AJAE, Vo. 78, No. 5.
4. Khan, M. A. and R. J. Supalla. 1997. "Elasticity of Demand for Nitrogen: Implications for Environmental Policy." Selected Paper, Southern Agricultural Economics Association Annual Meeting, Birmingham, Alabama, February 1-5.
5. Ahmad, S. and R. J. Supalla. 1997. "Potential Economic and Environmental Returns to Variable Rate Application of Nitrogen." Selected Paper, Southern Agricultural Economics Association Annual Meeting, Birmingham, Alabama, February 1-5.
6. Ahmad, S., R. A. Selley and R. J. Supalla. 1997. "Policy Alternatives for Improving Groundwater Quality in Irrigated Areas." Selected Paper, Western Agricultural Economics Association Annual Meeting, Reno, Nevada, July 13-16.
7. Ahmad, S., R. J. Supalla and W. M. Miller. 1997. "Precision Farming for Profits and Environmental Quality: Problems and Opportunities." Poster Paper, American Agricultural Economics Association Annual Meeting, Toronto, Canada, July 27-30.
8. Juliano, B. D. 1997. "Factors Affecting Nitrogen Management Practices of Corn Producers in Nebraska." Unpublished M.S. Thesis, University of Nebraska-Lincoln.
9. Sukharomana, R. "Willingness to Pay for Water Quality Improvement: Differences Between Contingent Valuation and Averting Expenditure Methods." Unpublished Ph.D. Thesis, University of Nebraska-Lincoln, 1998.
10. Sukharomana, R. and R. J. Supalla. 1998. "Effect of Risk Perception on Willingness to Pay for Improved Water Quality." Abstract, AJAE, Vol. 80, No. 5.
11. Supalla, R. J. and S. Ahmad. 1998. "An Economic Analysis of Precision Farming as a Tool to Improve Profits and Environmental Quality." Abstract, AJAE, Vol. 80, No. 5.

PROJECT CONTACT:

Name: Supalla, R. J.
Phone: 402-472-1792
Fax: 402-472-3460
Email: rsupalla@unlnotes.unl.edu

Item No. 2 of 27

ACCESSION NO: 0181518 SUBFILE: CRIS
PROJ NO: NEB-11-112 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 MAR 1999 TERM: 28 FEB 2004 FY: 2002

INVESTIGATOR: Eisenhauer, D. E.

PERFORMING INSTITUTION:
BIOLOGICAL SYSTEMS ENGINEERING
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

HYDROLOGIC MODELING AND ENGINEERING FOR ENHANCEMENT OF VEGETATIVE RIPARIAN BUFFERS

OBJECTIVES: The overall goal of this project is to improve the water quality enhancement by vegetative riparian buffers through better design and management. Specific objectives are: A. to adapt and validate models for simulation of the surface and vadose zone hydrology of riparian buffers and the hydrologic linkage with agricultural watersheds. B. to develop measurement techniques and sampling stragegies for quantifying the fate of surface runoff and sediment within riparian buffers. C. to quantify the spatial distribution of surface flow and infiltration in riparian buffers. D. to test design alternatives and management practices that enhance the water quality function of riparian buffers using the models developed in Objective A.

APPROACH: Techniques will be developed to evaluate the hydrology and water quality performance of vegetative riparian buffers and alternative designs of these systems. The project has two components: hydrologic modeling and field experimentation. The thrust of the modeling phase is to adapt and validate models that predict the ultimate fate and distribution of runoff water within buffers. A two-dimensional diffusive wave surface flow model will be adpated. The model will be used to evaluate the performance of alternative designs and management practices. Surface flow samplers and sampling schemes (placement, etc.) will be designed and tested. The flow samplers, which are variations of flow splitting techniques, will be used to provide data for model calibration and validation and to evaluate riparian buffers in "real-world" settings.

NON-TECHNICAL SUMMARY: The goal is to improve the water quality enhancement by vegetative riparian buffers through better design & management.

PROGRESS: 2001/10 TO 2002/09
A study was conducted on four farms in southeastern Nebraska to develop a method for assessing the extent of concentrated flow in riparian buffers and for evaluating the impact that it has on sediment-trapping efficiency. Field methods consisted of mapping field runoff areas and their pathways to and through riparian buffers to streams. Mathematical relationships were developed from a model (VFSMOD) that estimated sediment-trapping efficiency from the ratio of buffer area to field runoff area. Among the farms surveyed, riparian buffers averaged 9-35 m wide and gross buffer area ranged from 1.5 to 7.2 ha, but the effective buffer areas that acutally contacts runoff water was only 0.2 to 1.3 ha. Patterns of topgraphy and microrelief in fields and riparina zones prevented uniform distribution of field runoff across entire buffer areas. Using the mathematical relationships, it is estimated that riparian buffers at each of the four farms could potenially remove 99%, 67% 59% and 41% of sediment from field runoff if the runoff is uniformly distributed over the entire gross buffer area. However, because of non-uniform distribution, it was estimated that only 43%, 15%, 23%, and 34%, respectively, would actually be removed. The results indicate that concentrated flow through riparian buffers can be substantial and may greatly limit filtering effectiveness in this region. A related field study is being conducted at a surface irrigated site along Clear Creek in east-central Nebraska. Data collected by overland flow samplers and dye tracer studies revealed that both flow convergence and divergence can occur within a buffer. For accurate prediction of flow pathways with the buffer, a high resoultion (3 cm accuracy)topographic map was necessary. Runoff and sediment trapping from five typical irrigations, one simulated storm runoff event, and one large natural event were monitored. Overland flow was monitored in two areas (east and west grid) of an established vegetative filter. The spatial variation in soil hydraulic properties was measured. The inflow rate, outflow rate, and maximum depth of flow were measured at multiple locations. Simulation of the flow processes was performed using the physically based, distributed model, MIKE SHE. Simulations were performed with constant and variable topography and constant and variable soil hydraulic properties. The variable topography significantly impacted the outflow hydrographs for both the areas. The variable soil hydraulic properties impacted the outflow hydrographs with greater impact in the west grid than the east grid area. The outflow rate at the downstream edge of the vegetative filter varied with position along the downstream edge of the filter indicating flow is not uniformly distributed in the vegetative filter.

IMPACT: 2001/10 TO 2002/09
The project will lead to better design and management recommendations for riparian buffer systems. We anticipate that, nationally, up to 250 million tons per year of additional sediment could be trapped if the resulting practices studied in the project are implemented.

PUBLICATIONS: 2001/10 TO 2002/09
1. Dosskey, M.G., M.J. Helmers, D.E. Eisenhauer, T.G. Franti, and K.D. Hoagland. 2002. Assessment of concentrated flow through riparian buffers. Journal of Soil and Water Conservation. 57(6):336-343.
2. Helmers, M.J., D.E. Eisenhauer, T.G. Franti, and M.K. Dosskey. 2002. Modeling of two-dimensional overland flow in a vegetative filter. Paper No. 022165 Presented at the ASAE Annual Internation meeting. Chicago, Illinois, July 28-31.
3. Helmers, M.J., D.E. Eisenhauer, M.G. Dosskey, and T.G. Franti. 2002. Modeling vegetative filter performance with VFSMOD. Paper No. MC02-308 presented at the Mid-Central ASAE Meeting, St. Joseph, MO, April 12-13.

PROJECT CONTACT:

Name: Eisenhauer, D. D.
Phone: 402-472-1637
Fax: 402-472-6338
Email: BSEN099@unlvm.unl.edu

Item No. 3 of 27

ACCESSION NO: 0182309 SUBFILE: CRIS
PROJ NO: NEB-11-118 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUN 1999 TERM: 31 MAY 2004 FY: 2002

INVESTIGATOR: Martin, D. L.

PERFORMING INSTITUTION:
BIOLOGICAL SYSTEMS ENGINEERING
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

DEVELOPMENT OF SIMULATION AND OPTIMIZATION MODELS FOR WATERSHED MANAGEMENT

OBJECTIVES: The goal is to develop an integrated modeling framework to simulate the volume of groundwater and the concentration of nitrate-nitrogen in an aquifer that result from alternative irrigation and nitrogen management practices, tillage systems and other production practices. The socio-economic characteristics of producers will be incorporated to predict how growers select management practices when confronted with regional policies designed to conserve water and protect quality. The model will be used to evaluate management practices and policy alternatives for a portion of the Central Platte Valley. Specific objectives are to: 1. Develop a field-scale model to predict the amount of nitrate-nitrogen and water that leach from crop root zones, the volume of water pumped from irrigation wells and the amount of crop production for alternative management practices and irrigation systems. 2. Modify an existing watershed model to estimate surface water quality and transport. The model will be linked to a geographical information system (GIS) to access data and will be interfaced with both the field-scale model and the groundwater model. 3. Construct a three-dimensional groundwater model for a portion of the Central Platte Natural Resources District to predict the change of water levels and the concentration of nitrate-nitrogen in the aquifer. Transport functions will be incorporated to predict the travel time and rate of denitrification in the vadose zone. 4. Develop a farm management model for estimating producer responses to water quality policies including education, incentives and regulations. 5. Develop an optimization model to identify preferred district-wide policies and regulations subject to regional economic, water quantity and quality constraints.

APPROACH: We will develop an integrated modeling framework to simulate the volume of groundwater and the concentration of nitrate-nitrogen in an aquifer that result from alternative irrigation and nitrogen management practices, tillage systems and other production practices. We plan to simulate a portion of the Central Platte Natural Resources District that surrounds the Nebraska MSEA site. Extensive amounts of irrigated land in this area have led to the accumulation of excessive amounts of nitrate-nitrogen in the groundwater. Also since groundwater serves as the supply for irrigation, development has affected the aquifer and flows in the Platte River. There are five primary modeling components. A GIS will supply spatial information to all other programs. A farm and watershed model will simulate the leaching, deep percolation and pumpage for farms within the watershed. The adoption of management practices will be provided to the farm/watershed model based on regulatory policies. A groundwater model will be used to develop aquifer response functions to predict the nitrate concentration and the volume of groundwater given an amount of N leaching, deep percolation and pumpage. Data will be passed from the farm/watershed model through the GIS to an optimization program to compute the optimal set of management policies for given levels of N leaching, deep percolation and pumpage. Results from the optimization program and the groundwater quality and quantity will be provided to an optimal control model that will select the set of N leaching, deep percolation and pumpage that achieve the water quality and quantity objectives over a long-term period. A traceback algorithm will be developed to determine the optimal management practices and other spatial data once an optimal solution to the groundwater quality/quantity problem has been decided.

NON-TECHNICAL SUMMARY: Regulatory agencies need to develop effective policies to protect the quality and quantity of groundwater in agricultural areas. To develop computer programs that will assist regulatory agencies in developing more effective policies to protect groundwater

PROGRESS: 2001/10 TO 2002/09
A set of models for simulating the impact of surface irrigation management practices on deep percolation has been developed. We worked cooperatively with the USDA-ARS Water Management Laboratory in Phoenix to integrate the infiltration model into their model for the advance of water across the field and the distribution of infiltration along a furrow. Then we integrated simulated water distributions into a stochastic model for a field. This will allow us to develop field-scale estimates of nitrate leaching and water pollution from surface irrigated fields which represent some of the highest pollution potential. We have also been working to develop a hydrologic model of the Platte River Basin in Nebraska west of Columbus. We developed a computer program for simulating evapotranspiration, runoff and recharge from agricultural lands and native range. We continue to refine our estimates and to simulate the impact of agricultural practices on consumptive use and runoff. Simultaneously, we are establishing a set of eddy covariance towers to measure consumptive use at selected locations in the Republican River Valley. During the summer measurements were made on two producer fields in Franklin County. We also measured hydraulic properties of soil in the Frankly Supply Canal just east of Harlan County Dam. Return flows of water to the Republican River were also measured. These data will help determine the water balance for rural watersheds.Additionally, we are working with the Natural Resources Conservation Service to develop a model to predict the runoff potential for various sprinkler packages on center-pivot irrigation systems. The program will be used in Nebraska and across the Great Plains as part of the evaluation required for approval of funding for irrigation system modification under the EQUIP program.

IMPACT: 2001/10 TO 2002/09
These developments will allow us to better predict the quantity and quality of water in rural watershed. As agriculture faces more competition for water and as water quality continues to be lifted up as an environmental concern, we need to develop better prediction tools so that policy makers and agricultural users can better predict the outcome of their actions.

PUBLICATIONS: 2001/10 TO 2002/09
Skonard, C.J., 2002. A field-scale surface irrigation model. PhD dissertation. University of Nebraska-Lincoln. Lincoln, Nebraska

PROJECT CONTACT:

Name: Martin, D. L.
Phone: 402-472-1586
Fax: 402-472-6338
Email: dmartin2@unl.edu

Item No. 4 of 27

ACCESSION NO: 0133601 SUBFILE: CRIS
PROJ NO: NEB-12-173 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 05 JAN 1993 TERM: 31 DEC 1998 FY: 1999

INVESTIGATOR: Frank, K. D.; Denning, J. L.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

EVALUATING PLANT NUTRIENT NEEDS AND PRODUCT QUALITY

OBJECTIVES: 1. To cooperate with various ARD projects by providing chemical, physical & biological analyses of soil, plant & water samples. 2. Improve correlation & calibrations of soil testing methods currently available with crop response to lime & fertilizer treatment of a range of Nebraska soils. 3. Investigate & adapt new sample preparation procedures & new analytical techniques for water, plant & soil analyses. 4. Develop & update equations from correlation of NIRS analyses with wet chemistry forage & grain quality procedures.

APPROACH: 1. Maintain & operate a laboratory facility to service research projects needingelemental chemical analyses of soil, plant, water & grain & forage quality by NIRS & PSA of soils. 2. Cooperate with other research projects that generate field or greenhouse data for correlating or calibrating soil test methods with crop response or nutrient uptake. Analyze & use data from soil survey samples to refine soil test interpretation on basis of nutrient contribution of subsoil. 3. Develop & maintain NIRS equations for forage quality parameters using data from cooperating ARD & ARS projects for running both research & public samples. NIRS scans from selected research & commercial samples are equated to data from wet chemistry procedures by regression. 4. The accuracy of elemental analyses of forages & grain by NIRS/NIRT will be studied by comparing with EDXRF results.

NON-TECHNICAL SUMMARY: Rapid and accurate analysis of plant and soil nutrients is important for efficient use of nutrient resources in crop production. This project evaluated old and new methods of soil and plant analysis for accuracy and environmentally friendly methods.

PROGRESS: 1993/01 TO 1998/12
The main accomplishments during the life of this project were: 1) developed and/or improved N, P, K. Zn, S and lime recommendations for corn, wheat, sorghum, alfalfa, soybeans and pastures. 2) adapted Near-infrared Spectrometry (NIR) techniques to determine IVDMD, Crude Protein, NDF, ADF, and DM values for legume and grass hays, corn silage and feed grains. 3) Adapt NIR-T methods for predicting protein, oil, moisture, wet mill starch, and total starch for corn. 4) NIR-R and NIR-T to predict oil, protein and moisture for soybeans. 5) Develop the use of X-ray fluorescence to replace chemical digestion methods to determine, P, K, S, Cl, Mg, Mn, Zn, Fe, Cu and other minerals for plant, soil and organic amendments with success in most situations. Work is still underway to improve precision of determining, e.g., P in a mixed matrix (soil and manure mixture typical of open feedlots). 6) Investigations are underway to develop calibration and correlation equations to determine concentration of nutrients in liquid and dry fertilizers. 7) developed methods to replace chemical determination of easily oxidizable Carbon in soil by combustion (carbon/N analyzer). This involved destruction of excess lime in calcareous soils. 8) On-going collaboration with Super Critical Fluid Equipment Manufacture (ISCO) in developing extraction methods for oil and fat from grains (canola, corn, soybeans/meal and hydrocarbons from soil.) Also "energy packages" were developed for silages, haylages, and total mixed rations. Samples of canola, high oil corn and soybeans and sorghum from diverse areas are utilized to improve oil prediction equations by NIR-R and NIR-T. 9) Member of initial NIR forage analysis consortium to improve the precision of forage analysis values by NIR. 10) Collaborated with other land grant laboratories in developing North American proficiency testing program (soil and plant material). 11) Provided guidance to NE Dept of Agriculture to maintain accuracy in the NE soil and plant analysis check program for all laboratories operating in the state. 12) Cooperative study with commercial laboratories to a) develop correlation between ICP Sulfur and Ion Chromatograph determination of sulfate-S for soils; b) develop extraction techniques using Bray and Kurtz 1 to simultaneously determine Nitrate-N and phosphate-P by flow injection analysis (FIA). Continued refinement of methods for NIR-R, NIR-T and SFE will continue under normal laboratory.

PUBLICATIONS: 1993/01 TO 1998/12
No publications reported this period

PROJECT CONTACT:

Name: Cassman, K. G.
Phone: 402-472-1555
Fax: 402-472-7904
Email: kcassman1@unl.edu

Item No. 5 of 27

ACCESSION NO: 0155682 SUBFILE: CRIS
PROJ NO: NEB-12-209 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: REVISED
START: 01 OCT 2001 TERM: 31 AUG 2006 FY: 2002

INVESTIGATOR: Spalding, R. F.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

PROCEDURES FOR ASSESSING IMPACTS OF NONPOINT AGRICHEMICALS ON GROUNDWATER

OBJECTIVES: The impacts of farm scale conversions to improved herbicide management alternatives on shallow groung water quality wil be investigated at the sprinkler-irrigated MSEA site and at furrow irrigated fields in Nebraska. Changes in herbicide loading to shallow ground water will be evaluated using systems of multilevel samplers and ground water dating. Impacts of runoff and infiltration through grassed buffer strips will be investigated at the farm scale paired watersheds on the water quality in Clear Creek and on shallow ground water beneath the biffered areas. The paired watersheds will allow for comparability between herbicide loss in runoff transported through the buffered and non-buffered row cropped fields. Seven sutomatic ISCO samplers are installed at strategic points in the stream to allow for runoff monitoring of sediment, nitrate, ammonia and herbicides and their transformation products. Chemical infiltration beneath the strips will be detected with lysimeters and multilevel samplers.

APPROACH: Demonstrate performance of amended biodenitrification at a municipal well field in Wahoo, Nebraska. Multilevel samplers will be monitored to determine the degree of treatment within the denitrification zone.

NON-TECHNICAL SUMMARY: Irrigation management impacts ground and surface water quality. Ground water nitrate can be treated by in situ denitrification. This project examines the impact of management alternatives on ground water and surface water quality. This project devlops in situ aquifer methods to remediate ground water nitrate concentrations.

PROGRESS: 2001/10 TO 2002/09
Two manuscripts are now in press that may change researchers' approaches to understanding non point pesticide contamination in shallow aquifers. The data indicate that past reliance on vulnerability models using soil permeability (type), depth to ground water and irrigation to delineate areas vulnerable to pesticide contamination is oversimplified. Results from the four year monitoring study at the NE-MSEA indicate peak pesticide loading to the shallow ground water occurs prior to irrigation after intense storms in specific locations on and off cultivated fields. Recharge areas occurred in field ditches and low spots and especially in road ditches which normally surround each section. N-15 analysis of nitrate in groundwater beneath cropland fertilized with animal and meat processing lagoon wastes indicate that both heterotrophic and dissimilatory nitrate reduction to ammonia occurred. Results of the in situ biodenitrification project at Wahoo, NE municipal well field indicate that the pilot treatment was successful. Two manuscripts describing the fate and transport of ethanol and MTBE in ground water are in the final stages of polishing before submission.

IMPACT: 2001/10 TO 2002/09
A re-evaluation of the dominant mechanisms for pesticide contamination of shallow ground water is needed. Natural attenuation of nitrate occurred in areas where excessive waste applications occurred and appears responsible for keeping average ground water nitrate concentrations close to compliance levels. The successful in situ treatment of nitrate contaminated ground water at the Wahoo well field indicates that the method will provide an economic alternative for municipalities. The only available alternatives are very expensive above ground treatments.

PUBLICATIONS: 2001/10 TO 2002/09
1. Spalding,R.F., Snow, D.D., and Exner, M.E. 2002. Acetamides and their transformation products in ground water beneath Nebrsaksa's Management Systems Evaluation Area. p. 125-128. In T. Albanis (ed) Proceedings of the 2nd Europeon Conference on pesticide and related organic micropolutatants in the environment. University of Ioannina, Corfu, Greece, Sept. 26-29.
2. Exner,M.E., Harrell D., Larsen, P.L.. Romary C., and Spalding, R.F. 2002. A quality assessed database for pesticides in ground water. p.87-92.In T. Albanis (ed) Proceedings of the 2nd Europeon Conference on pesticide and related organic micropolutatants in the environment. University of Ioannina, Corfu, Greece, Sept. 26-29.
3. Snow, D.D., Cassada D.A., Monson S.J., Zhu J., and Spalding R.F. 2002. Trace analysis of tetracycline and macrolide antibiotics using solid phase extraction and liquid chromatography tandem mass spectrometry. In: Abstracts of Papers, 223rd ACS National Meeting, April 7-11. Orlando, FL.

PROJECT CONTACT:

Name: Spalding, R. F.
Phone: 402-472-8214
Fax: 402-472-9599
Email: rspalding@unl.edu

Item No. 6 of 27

ACCESSION NO: 0159768 SUBFILE: CRIS
PROJ NO: NEB-12-228 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 01 NOV 1992 TERM: 30 APR 1998 FY: 1999

INVESTIGATOR: Sander, D. H.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

INCREASING FERTILIZER EFFICIENCY FOR GRAIN CROPS

OBJECTIVES: 1. Increase efficiency of N and P fertilizer through improved methods of applications. 2. Improve fertilizer recommendations based on soil tests by improved soil sampling & by quantifying corn N uptake in relative to time of N application & degree of N deficiency. 3. Determine reserve capacity of Nebraska soils to supply P before yield response to fertilizer P can be effected.

APPROACH: Fertilizer efficiency will be improved by studying various methods of application in field experiments. Approaches for P will involve manipulating soil-fertilizer contact and root-fertilizer contact to maximize fertilizer uptake. Nitrogen fertilizer efficiency will be improved by studying the effect of delayed soil sampling time on the accuracy of soil test prediction of N need and by evaluating the quantitative effect of time of N application on yield increases under various degrees of N deficiency. Greenhouse and laboratory studies will be used to evaluate the long-term ability of Nebraska soils to supply P.

PROGRESS: 1992/11 TO 1998/04
Two long-term experiments were established in 1996 and 1997 to determine the fertilizer N equivalency and N mineralization of various rates of biosolids obtained from the City of Lincoln's waste treatment plant. One experiment is on continuous irrigated corn and the other on continuous dryland grain sorghum. Rates of biosolids are being applied each year to new plat areas and residual N effects determined from previous applications. N mineralization is being determined from in situ mineralization cans located in the experimental area. Soil moisture and temperature are being monitored. Data generally indicates that for irrigated corn the rate of biosolids that produced maximum yield the first year would produce 83 and 66% of maximum one and two years after applied. The biosolids rate that produced maximum yield the first year for dry land sorghum resulted in 89 and 77% of maximum one and two years after applied. At these rates the biosolids would be half as affective 1.4 years after application for irrigated corn and 1.9 years after application for dry land sorghum.

PUBLICATIONS: 1992/11 TO 1998/04
1. Sander, D.H., and B Eghball. 1999. Planting date and phosphorus fertilizer placement effects on winter wheat. Agron. J. 91:707-712.
2. Binder, D.L., and D.H. Sander. 1998. Border row effect on corn grain response to sidedressed nitrogen fertilizer. Commun. Soil Sci. Plant Anal. 29 (9&10):1349-1354.


Item No. 7 of 27

ACCESSION NO: 0168886 SUBFILE: CRIS
PROJ NO: NEB-12-244 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 05 JUL 1995 TERM: 30 JUN 2000 FY: 2001

INVESTIGATOR: Powers, W. L.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

SOIL PHYSICAL RELATIONSHIPS FOR BEST MANAGEMENT PRACTICES TOPROTECT WATER QUALITY

OBJECTIVES: A. Establish criteria for selecting best management practices (BMPs) based on soil physical relationships which affect surface and ground water quality. B. Determine the effect of present BMPs on soil physical relationships which affect surface and ground water quality.

APPROACH: To achieve objective A, the LEACHM (Leaching Estimation and Chemistry Model) will be used to develop and evaluate remediation practices (based primarily on soil physical relationships) for soils contaminated with munitions (TNT, RDX, etc). This same model along with others will be used to select irrigation regimes for turf grass. A simple technique using a sieving technique will be used to quantify the shape of soil aggregates which can effect fate and transport of agrichemicals. To achieve objective B, the effect of long-term best management practices (BMPs) for applying animal and municipal by-products to soil will be examined in light of their influence on the K factor of the Revised Universal Soil Loss equation (RUSLE) and on soil physical properties such as infiltration rate (permeability), pore size distribution, bulk density, and dry aggregate size distribution.

NON-TECHNICAL SUMMARY: NA

PROGRESS: 1995/07 TO 2000/06
The purpose of this project was to establish soil physical relationships for selecting BMPs and to examine the effect of present BMPs on soil physical relationships. This project consisted of the following four field studies: (1) Alternative production system effect on the K-factor of the Revised Universal Soil Loss Equation; (2) Soil quality assessment after weed-control tillage in a no-till wheat-fallow cropping system; (3) Soil condition as influenced by cropping and tillage systems in the Central High Plains; and (4) Spatial characterization of soil physical properties in irrigation furrows. Study (1) indicated that alternative production systems do affect the K-factor of some soil series and can reduce soil erodibility and erosion. Study (2) showed that occasional tillage with the moldboard plow in a reduced or no tillage management system for wheat will help control winter annual grass weeds without destroying the soil physical benefits of conservation tillage. Study (3) showed that the type and frequency of tillage and cropping systems do affect some soil physical properties. Water infiltration rates were affected as conventional-till (CT) systems tended to have slower intake rates than reduced-till (RT) and no-till (NT) systems. Bulk density under CT systems was greater than that under NT systems. Study (4) showed that the saturated hydraulic conductivity, bulk density, and penetrometer resistance differ significantly among each furrow in an eight-row equipment pass. However, this repeating pattern for penetrometer resistance was not significant below the six-inch soil depth.

IMPACT: 1995/07 TO 2000/06
Study (1): Alternative production systems do affect the K-factor of some soil series and should be taken into consideration when developing conservation plans. Study (2): Because occasional plowing (every 5-6 yrs or so) to control annual grasses has no detrimental long-term effect on the physical quality of soils, the adoption of this relatively inexpensive practice for no-till systems could improve the economic return from land in the High Plains of the United States. Study (3): Although the soil physical properties evaluated varied with tillage/cropping system, no one system seems superior in all aspects. Thus High Plains producers can use any of the evaluated systems as best management practices. However, soil physical properties should be monitored on an ongoing basis. Study (4): Field measurements from this study should be useful in furrow-irrigation simulation models to find environmentally favorable and less expensive water management options.

PUBLICATIONS: 1995/07 TO 2000/06
1. Kessavalou, A., J.W. Doran, W.L. Powers, T.A. Kettler, and J.H. Qian. 1996. Bromide and nitrogen-15 tracers of nitrate leaching under irrigated corn in central Nebraska. Journal of Environmental Quality. 25:1008-1014.
2. Woodbury, B.L., S.D. Comfort, and W.L. Powers. 1996. An automated sampling system for large soil column transport studies. Transactions of the American Society of Agricultural Engineers. 39:2163-2166.
3. Aslan, M., J. Skopp, and W.L. Powers. 1998. Modified proportional model for time-dependent sieving. Soil Science. 163:472-481.
4. Powers, W.L., M.L. House, R.D. Tejral, and D.E. Eisenhauer. 1999. A simultaneous data collection system for several soil water release curves. Applied Engineering in Agriculture. 15:477-481.
5. Krishnan, G., G.L. Horst, S. Darnell, and W.L. Powers. 1999. Growth and development of smooth bromegrass and tall fescue in TNT-contaminated soil. Environmental Pollution. 101:1-8.
6. Kettler, T.A., D.J. Lyon, J.W. Doran, W.L. Powers, and W.W. Stroup. 2000. Soil quality assessment after weed-control tillage in a no-till wheat-fallow cropping system. Soil Science Society of America Journal. 63:339-346.
7. House, M.L., W.L. Powers, D.E. Eisenhauer, D.B. Marx, and D. Fekersillassie. 2001. Spatial analysis of machine-wheel traffic effects on soil physical properties. Soil Science Society of America Journal. 64:Sept-Oct.

PROJECT CONTACT:

Name: Powers, W. L.
Phone: 402--472--1529
Fax: 402-472-7904
Email: wpowers@unlnotes.unl.edu

Item No. 8 of 27

ACCESSION NO: 0170848 SUBFILE: CRIS
PROJ NO: NEB-12-252 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: REVISED
START: 01 MAR 2001 TERM: 28 FEB 2006 FY: 2002

INVESTIGATOR: McCallister, D. L.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

BIOSOLIDS APPLICATION AND SOIL CHEMICAL PROPERTIES: CHANGES IN PHOSPHORUS AND CARBON POOLS

OBJECTIVES: 1. To measure changes in P availability and chemical fractions from biosolids applied to soil. a. To determine the effect of biosolid N content on P availability in soil. (hypothesis: Increased biosolid N content will increase availability of P from biosolids) b. To determine the effect of management (principally tillage and time of application) on fractions and distribution of P in biosolid-amended soils. (hypothesis: Application and incorporation of biosolids during periods of high biological availability will partition P into available forms) c. To determine the potential for and factors controlling leaching of P under conditions of heavy biosolid application on vulnerable soils. (hypothesis: Heavy applications of biosolids to vulnerable soils will result in P leaching below the root zone) d. To evaluate non-traditional methods of estimating bioavailable P in biosolid- amended soils. (hypothesis: Methods not currently in routine use will provide better estimates of bioavailable P than traditional fertility tests for soils receiving biosolids) e. To evaluate changes in soils of border buffer strips with age and management as affecting the strips' ability to protect surface water from P inputs. (hypothesis: The ability of border buffer strips to retard P movement to waterways degrades with time after installation) 2.To identify changes in soil organic matter quality and content resulting from application of biosolids. a. To monitor changes in soil organic matter (SOM) fractions with biosolid application. (hypothesis: Application of biosolids will increase both quantity and quality of SOM) b. To determine the persistence of changes in SOM fractions after termination of biosolids application. (hypothesis: Both quantity and quality of SOM will decline with time after termination of biosolids application)

APPROACH: 1a. Soils will be sampled from plots cropped with corn or alfalfa and receiving combinations of low and high P manure composts with and without inorganic N fertilizer annually since 1998. Analyses will include Bray and Kurtz-extractable P, inorganic and organic P, and more detailed fractionations. 1b. Soils will be sampled from a companion study to that of 1a. Here, low and high P manure composts have been applied since 1998 with different management: preplant with incorporation, postplant without incorporation, and winter without incorporation. Comparison of appropriate treatments will allow isolation of a time of application effect and an incorporation effect. Soil analyses are same as in 1a. 1c. Soils from sites which have received heavy biosolids application will be sampled by depth and analyzed for P fractions, especially those that suggest mobility. These will be compared with similar soils which have not been amended with biosolids. If evidence suggests P leaching, intact soil cores will be taken from unamended locations. Cores will be leached with slurries of biosolids under laboratory conditions. Leachate composition will be monitored for potentially mobile P forms. At the completion of the experiment, cores will be sectioned and progress of the biosolid P will be measured. Results will be compared with soluble P analyses from soil and soil water samples down gradient of animal waste retention ponds. Such ponds will offer a low volume but high concentration source of P. 1d. Soils with and without application of biosolids will be analyzed for bioavailable P using traditional and non-traditional methods. Some methods considered include Bray and Kurtz, Olsen, Mehlich III, iron oxide strip, P saturation, water-extractable P, and phosphatase activity. Methods will be evaluated based on their sensitivity, consistency, and relationship to biological productivity. 1e. Field-edge vegetative filter strips (VFS) of different ages and different construction techniques will be identified. Soils in the VFSs will be sampled perpendicular to the extent of the strip, as will soils in similar locations without VFSs. Changes in the soils will be quantified, particularly those relevant to the ability of the VFS to retain P from upslope applications of biosolids. Properties will include total, inorganic, and organic P; soil organic matter; texture; and carbonate content. 2a.Soils will be sampled by depth to investigate the impact of manure application on C accumulation. Sequestration of total C and C fractions will be related to manure properties, rate of application, and management. Beneficial and detrimental changes in soil properties related to manure application will be measured. 2b. Plots on which biosolids application has been ended will be identified. Properties related to biosolids will be followed over time to determine their rate of change. Properties measured include total C, C fractions, cation exchange capacity (CEC), total N, nitrate-N, ammonium-N, C/N ratio, and aggregate size and stability. The change in these properties over time will be related to initial properties of the biosolids, application rate, and management.

NON-TECHNICAL SUMMARY: Animal and human manures (biosolids) can be a beneficial source of nutrients and carbon in soils, but require a high degree of management. This project will identify factors related to how a soil holds phosphorus and carbon and what management choices can improve that ability.

PROGRESS: 2001/10 TO 2002/09
We conducted a study to examine the influence of surface applications of low and high phosphorus (P) composted beef cattle manure on P sorption by soils. Principal treatments involved high P composted manure applied at a nitrogen (N) rate, low P composted manure applied at an N rate, and inorganic N fertilizer with no P, all treatments for three years. Total P applications for the different treatments over the three years of the study were 1134, 756, and 0 kg ha-1 respectively. The plot area exhibited substantial textural differences so we analyzed coarse and medium textured soils separately. Phosphorus Indices (PI) of both composted manure treatments, determined with an initial P concentration of 75 mg P/kg soil and 1 g soil:20 mL solution, were higher than of N only in the 0.0-2.5 cm soil depth. The differences were not significant, however. No differences among treatments were evident at depths below 2.5 cm. Phosphorus Indices of the 0.0-2.5 cm depth samples were significantly higher than other depths for both composted manure and N only treatments. Phosphorus Indices of medium-textured soils were higher than of coarse-textured soils. Despite the lack of significant treatment effect, we expect that application of composted manure for longer periods than the 3 years of this study will reduce the ability of soil to hold additional P. Such a reduction may have a negative effect on water quality if manure is surface-applied or if manure-amended soil is lost because of erosion.

IMPACT: 2001/10 TO 2002/09
Retention of phosphorus (P) from animal manure by soil is of significant interest because it allows livestock producers to dispose of a waste and crop producers to use the P in the waste as fertilizer. If the P is not held by soil particles, however, it may contribute to degradation of ground or surface water quality. We hypothesized that application of composted manure over a period of years would reduce the ability of soils to hold more applied P and so possibly contribute to its loss. In this experiment, we used high P and low P manures, produced by feeding beef cattle high and low P rations. We found that our hypothesis was not supported, specifically that manure application did not reduce the ability of the soils in the study to hold more P. Both soils' ability to hold P was comparable to a treatment that had received only fertilizer nitrogen. While this result is encouraging because it suggests that manure can continue to be applied on soils at high rates with little concern for accelerated P loss, it is possible that the three year period of application used in this study is inadequate to produce the changes we anticipated. Therefore, we hope to continue the study and possibly identify if and when increased P loss will become a problem.

PUBLICATIONS: 2001/10 TO 2002/09
1. Akhtar, M., D.L. McCallister, and K.M. Eskridge. 2002. Availability and fractionation of phosphorus in sewage sludge-amended soils. Commun. Soil Sci. Plant Anal. 33:2057- 2068.
2. McCallister, D.L., M. Mamo, D.T. Walters, and R.R. Renken. 2002. Manure phosphorus concentration and its effects on soil chemical and depth phosphorus distribution. Agron. Abstr. Am. Soc. Agron. Madison, WI.

PROJECT CONTACT:

Name: McCallister, D. L.
Phone: 402-472-6312
Fax: 402-472-7904
Email: dmccalli@unlnotes.unl.edu

Item No. 9 of 27

ACCESSION NO: 0171247 SUBFILE: CRIS
PROJ NO: NEB-12-253 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED MULTISTATE PROJ NO: NC-218
START: 01 OCT 1995 TERM: 30 SEP 2000 FY: 2001

INVESTIGATOR: Walters, D. T.; Sander, D. H.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

CHARACTERIZING NITROGEN MINERALIZATION AND AVAILABILITY IN CROP SYSTEMS TO PROTECT WATER RESOURCES

OBJECTIVES: 1) Determine the feasibility of using thermal units coupled with an appropriate method of potentially mineralizable soil N to predict current season N availability. 2) Characterize the active C and N pools subject to mineralization in cropping systems.

APPROACH: Chemical and microbiological measurements of potentially mineralizable soil nitrogen will be interfaced with real-time soil degree day measurements to predict N supply to corn. Failure rate of current soil testing strategies will be analyzed with respect to both soil supply and plant demand for nitrogen. Separation of soil residual nitrate use efficiency from native soil N mineralization and fertilizer N use will be accomplished with dual tracer technology using 15-N and Br as indicators of fertilizer and corn root activity, respectively.

NON-TECHNICAL SUMMARY: Nitrogen (N) fertilizer use is the largest energy input in maize production systems. Excessive N use contributes to ground and surface water nitrate contamination. Previous work has shown that uncertainty in predicting maize N need is due to variation in soil N mineralization. The principal objective of this project is to improve the efficiency of N use in maize production systems. We will attempt to couple cumulative soil thermal units with a measure of potentially mineralizable soil nitrogen to yield a real-time prediction of soil N mineralization as the season progresses.

PROGRESS: 1995/10 TO 2000/09
Current strategies used for formulating fertilizer N recommendations to corn in the North Central region of the U.S. rely in large part on soil nitrate testing as a measure of soil N supply. Fertilizer N use efficiency, however, averages less than 40% in corn systems because of our inability to predict native soil N supply that is mineralized as the growing season progresses. The principal objective of this North-Central regional research project was to obtain a quantitative, real-time measure of soil N mineralization during the course of the maize growing season as well as a real-time measure of plant N status with the SPAD chlorophyll meter. Soil N mineralization was quantified on a total of 74 intensively monitored sites by coupling on-site soil temperature with laboratory determined kinetic parameters from long-term aerobic incubations.Each site was monitored throughout the growing season with measurement of soil N mineralization, soil nitrate-N concentration, periodic biomass yield as well as absolute and relative SPAD chlorophyll meter readings to monitor crop N status during plant development. In addition, traditional soil nitrate testing strategies of sampling soil pre-plant (PPNT) and at V8-10 stage (PSNT) were conducted. Soil N mineralization between PPNT and PSNT sampling times averaged 24 kg N/ha but ranged between 0.27 and 129 kg N/ha. The PSNT was ineffective in predicting relative yield with more accuracy than PSNT. We observed that an average of 63% of N mineralized during the growing season (range 29% - 78%) occurred after the PSNT sampling time. Soil N mineralization was greater where highly labile N sources such as manure or alfalfa residues were amended to soil. These data show that post-sidedress-time soil N mineralization contributes significant quantities of N and that real-time assessment of maize N status would provide the opportunity for significant N savings and improvement in fertilizer N use efficiency. To that end, analysis of the SPAD readings taken at each site indicated that the SPAD meter was an effective measure of plant N status but only after the V10 stage of growth. A significant proportion of sites with high PSNT failure rate (12%) were those where a low harvest index indicated grain development and internal physiological N use efficiency was impaired. An important effect of annual variation in soil N mineralization is the impact on fertilizer N use efficiency. Plant fertilizer N uptake efficiency was measured at each site. As expected, site fertilizer N use efficiency declined as a function of fertilizer N rate. Fertilizer use efficiency at the point of economic which is the figure most optimum N rate and averaged 37% with a standard deviation of 30%. Ten soil mineralization quick tests have been evaluated for each site to quantify the size of the potentially mineralizable N pool size. A number of these show promise in the identification of sites with highly labile N pools but further analysis of these data must be done to identify proper application of these tests. An extensive database of these sites has been compiled for publication and distribution to the scientific community.

IMPACT: 1995/10 TO 2000/09
Improvement in corn nitrogen use efficiency is key to reduction in off-site nutrient load to aquatic systems and ground water. This multi-state project has provided quantitative data on the annual amount of native soil N supply as well as criteria for real-time assessment of corn N status that can be used to improve the prescription of fertilizer N need. This project provides improved N management criteria to reduce nitrogen load to the environment and increase farm profitability.

PUBLICATIONS: 1995/10 TO 2000/09
No publications reported this period

PROJECT CONTACT:

Name: WALTERS, D. T.
Phone: 402-472-1506
Fax: 402-472-7904
Email: dwalters1@unl.edu

Item No. 10 of 27

ACCESSION NO: 0178721 SUBFILE: CRIS
PROJ NO: NEB-12-269 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUL 1998 TERM: 30 JUN 2003 FY: 2002

INVESTIGATOR: Caldwell, R. M.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

CROPPING SYSTEMS FOR UNCERTAIN ENVIRONMENTS: DECISION AIDS FOR MANAGING SOIL & WEATHER VARIABILITY

OBJECTIVES: 1. Test the ability of existing crop models, including those provided through commercial Internet-based services, to predict weather by soil by genotype by management interactions. Develop recommendations for their use by farmers & by researchers. 2. Test the hypothesis that variable rate fertilizer application based on site specific fertilizer response curves outperforms the best uniform application strategy and outperforms the best variable rate application srategy that uses fertilizer response curves calibrated on a regional level. 3. Test hypotheses about the current loss of sorghum acres from regions in Nebraska, to find out whether the change is justified based on agronomic reasons.

APPROACH: Existing data sets & the results of ongoing experiments in Nebraska will be computerized using data formats that conform to international standards. Crop simulation models (initially ALMANAC. CropSys, ecosys, INTERCOM, PCYield) will be collected and, where necessary, modified to read input data from the database. Model predicitions will be compared to experimental observations to see how well the models can account for soil by weather by genotype by management interactions. Qualitative apsects of the models will also be compared, and recommendations for their use developed. A coordinated modeling on foarm research effort will test streategies for fertilizer management. Empirical and mechanistic models will be developed and tested for their value in identifying site specific nutrient response functions. Small plot experiments will be harvested by hand and field scale experiments will be harvested with yield mapping combines. To evaluate ongoing changes in farmer practices in eastern Nebraska, county level agricultural statistics will be analysed to test among various hypotheses that may account for the loss of sorghum acres in the region. Genetic gains, improvements in water use efficiency, climatic shifts, and economic opportunities will be qualtified and compared to see which best accounts for the observed changes in cropping systems.

NON-TECHNICAL SUMMARY: Farmers face so many unique weather and soil combinations that general recommendations don't always work well. New computer technology might solve some of the problem. We plan to test decision support tools to see whether they can improve risk management and site-specific farming.

PROGRESS: 2001/10 TO 2002/09
This year the project concentrated on analysis of data from on-farm research, on-station research, and historical records of statewide and county production statistics. Computer simulation models, in the JanuSys framework, were used to help test hypotheses about the processes that limited yields. In an analysis of data from individual corn plants that were subject to variability in plant spacing and emergence, control of kernel set was one of the most important factors determining plant yield. Improved models are needed for effects of plant-to-plant competition on growth in plant height, delays in silk emergence, and kernel abortion. A spatial/temporal pattern analysis of historical records for county-level acreage of dryland corn and sorghum showed that Nebraska is currently in a period of rapid loss of diversity in its coarse grain production. We have developed a weather database that allows us to use computer simulations to analyze weather effects on crop yields going back to the 1800s. We will use it to help test hypotheses about why Nebraska farmers are reducing sorghum acreage. With over 2000 acres of yield mapped experiments studying N fertilization of soybean, we found no case in which the fertilizer increased yield. Current work is focused on modeling within-field variability in response and analyzing factors that may have contributed to the lack of a yield response, including levels of nitrate-nitrogen applied to the crops through irrigation. Research was also initiated on in-season N fertilization of corn.

IMPACT: 2001/10 TO 2002/09
By putting zero-fertilizer control plots in their on-farm experiments, each of our cooperating farmers saved hundreds of dollars relative to a whole-field application of N fertilizer that did not increase soybean yield. Nebraska farmers could loose millions of dollars if they apply nitrogen on soybean fields that don't respond to the fertilizer.

PUBLICATIONS: 2001/10 TO 2002/09
Caldwell, R.M. 2003. Analysis of cropping systems and use of decision support systems. J. Crop Production. (in press)

PROJECT CONTACT:

Name: Caldwell, R. M.
Phone: 402-472-4792
Fax: 402-472-7904
Email: rcaldwell1@unl.edu

Item No. 11 of 27

ACCESSION NO: 0185063 SUBFILE: CRIS
PROJ NO: NEB-12-278 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 APR 2000 TERM: 31 MAR 2005 FY: 2002

INVESTIGATOR: Walters, D. T.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

DYNAMIC NITROGEN MANAGEMENT STRATEGIES FOR OPTIMIZING MAIZE YIELD AND N USE EFFICIENCY

OBJECTIVES: The overall objective of this project is to gain an understanding of the dynamic relationship between leaf nitrogen distribution within the maize canopy for the purpose of establishing diagnostic guidelines for real-time nitrogen management strategies. The results obtained should also provide a quasi-mechanistic explanation of the variation observed in remote sensing of plant nitrogen status which generally relies on the reflectance properties of the uppermost leaves of the maize canopy. Specific objectives are as follows: 1.Determine the relationship between SPAD reading (specific leaf chlorophyll (SLChl),umol chl m-2) and maize SLN (g N m-2) as a function of plant age and leaf position. 2.Determine the relationship between whole-plant SLNwp (g N m-2 leaf) for maize hybrids with demonstrated difference in harvest index (HI,Ygrain/Ytotal). 3. Determine the dependence of area-based whole-plant SLNab (kg Nleaf ha-1) to maize population density under variable nitrogen supply. 4.Compare N management strategies that incorporate real-time SLN diagnosis with conventional soil testing strategies.

APPROACH: Experiments will be conducted with farmer cooperators on irrigated field sites across Eastern NE. Sites and hybrids will be selected on basis of known hybrid characteristics, soil type and proven farmer management. Experimental design will be randomized complete block with treatments of four N application rates (0, 80, 160, and 240 kg N ha-1)to establish a range in N supply, and four sampling time/diagnostic leaves (V8, V12, VT and VTE). Specific leaf N and chlorophyll will be determined for diagnostic leaves as well as whole plant leaf profiles (with leaf area index) from V8 through physiological maturity. Changes in plant N distribution will be explored as a function of N supply regime, hybrid (harvest index) and population density. On the basis of leaf diagnostic criteria determined from the preceding experiments, an N managment strategy will be tested whereby real-time determination of optimum maize leaf N distribution will be used to trigger nitrogen doses. This plant based diagnostic strategy will be compared to conventional soil-test based fertilizer N management with respect to physiological and agronomic efficiency.

NON-TECHNICAL SUMMARY: A. Nitrogen management decisions based on soil testing alone result in low use efficiency. B. Excess nitrogen use contributes to ground water contamination, hypoxia and poor energy use efficiency in maize production systems. A. This project examines the real-time diagnosis of plant nitrogen status to improve the precision of nitrogen fertilzer requirements. B. The results fo this project should reduce total nitrogen use and improve efficiency of energy and material use in maize production systems.

PROGRESS: 2001/10 TO 2002/09
Studies were conducted on twelve sites across the state of Nebraska. The range of sites chosen encompass the major agroecological zones devoted to maize production in Nebraska. Four maize hybrids were grown under a gradient of N availability and an additional experiment was conducted to test the effect of planted row spacing and population on grain yield, harvest index and yield components. A factorial experiment was conducted with two population levels (30 and 44 thousand plants/acre) and two row spacings (15 and 30 inch). Measured yield components included 100 seed weight, kernels per ear and kernel weight per area as well as leaf area index. Data analysis of yield components have not been completed to date. Yield analysis indicated that early planting (April 15) was detrimental to final yield because of higher night temperatures during grain fill. The usual recommended optimum date of planting is mid-April but simulation modeling has suggested that the probability of avoiding late season temperature stress during grain filling is reduced if planting date is delayed to May 1 or beyond. Nitrogen fertilizer rate also had a significant effect on yield whereby high N rates at high population resulted in greater vegetative biomass and lower yield at early (April 15) planting dates. There was no effect of row spacing on yield. The higher population, however, resulted in significantly lower percent of tillered plants (10% vs 0 for 30M and 44M populations, respectively) and a resultant higher harvest index.

IMPACT: 2001/10 TO 2002/09
Maize nitrogen use efficency will depend on the energy expended by the plant in maintenanace respiration especially during grain fill. Planting time and hybrid selection strategies that reduce vegetative respiration losses and optimize energy harvested for grain production will result in measureable increases in N use efficiency as measured in grain production rather than total biomass production.

PUBLICATIONS: 2001/10 TO 2002/09
Cassman, K, A. Dobermann and D. Walters. 2002. Agroecosystems, nitrogen use efficiency and N management. Ambio 31(2):132-140.

PROJECT CONTACT:

Name: Walters, D. T.
Phone: 402-472-1506
Fax: 402-472-7904
Email: DWALTERS1@UNL.EDU

Item No. 12 of 27

ACCESSION NO: 0192015 SUBFILE: CRIS
PROJ NO: NEB-12-289 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JAN 2002 TERM: 31 DEC 2007 FY: 2002

INVESTIGATOR: Dobermann, A. R.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

PRECISE NUTRIENT MANAGEMENT IN CORN-BASED SYSTEMS

OBJECTIVES: To develop generic relationships describing nutrient requirements of corn and soybean as a function of climatic/genetic yield potential and interactions between N, P, and K. To identify differences among corn hybrids in effects of potassium on K uptake, grain yield and stalk strength. To develop new procedures for spatially dense mapping of soil properties and integration of multivariate spatial data for defining management zones in site-specific management. To evaluate the agronomic, economic, and environmental performance of site-specific nutrient management.

APPROACH: Through a combination of field research activities and modeling, this research aims at developing a quantitative basis for: (a) predicting the attainable yield as a function of the climatic and genetic yield potential and plant nutrient accumulation. (b) predicting the amount of fertilizers required as a function of the required crop uptake, nutrient supply from indigenous sources, and fraction of fertilizer nutrients recovered in the plant, (c) characterizing the nutrient supply from indigenous (soil) sources and its variability in space and time, and (d) increasing the recovery efficiency of dynamic nutrients such as N through real-time management. Specific research activities include: (i)field data collection to model nutrient requirements of corn, (ii) field and laboratory research to understand genotypic variation in corn response to potassium supply, (iii) development of geostatistical procedures for thematic mapping of soil properties and management zones, and (iv) field experiments to evaluate different strategies for site-specific nutrient management in corn at three sites in Nebraska.

NON-TECHNICAL SUMMARY: Future crop management will require fine-tuning of nutrients to (a) yield levels that approach yield ceilings, (b) different groups of plant traits , and (c) spatial and temporal variability in nutrient supply and crop demand. The goal of this project is to develop a generic strategy for precise management of plant nutrients in corn-based systems. The underlying hypothesis is that yields of 70 to 80% of the climatic yield potential provide the best combination of high profitability, food production, and minimal environmental impact.

PROGRESS: 2001/10 TO 2002/09
Data from various soil fertility studies conducted during 2000 to 2002 suggest that (i) current fertilizer recommendations do not allow expression of full attainable yield, (ii) high corn yields require higher plant density and greater N and K uptake per unit yield, (iii) existing corn growth simulation models underestimate the actual dry matter production and yield measured at near-optimum growth conditions in the field, (iv) achieving high nitrogen use efficiencies at yield potential levels is possible, but requires a dynamic approach to N management, and (v) the potential to increase C sequestration is greatest in continuous corn systems with intensive management. A new corn growth model, Hybrid-Maize, was developed and validated and is currently being used in simulating yield potential and carbon sequestration scenarios in corn systems. In 2002, twelve new fertilizer trials aiming at high yields were established along an agroecological gradient in Nebraska. Research on site-specific management was initiated at four sites and detailed sampling was conducted. New geostatistical techniques for thematic high-resolution mapping of soil properties were evaluated. The use of spatially dense secondary information such as a digital elevation model (DEM) on-the-go sensed electrical conductivity (Veris sensor), bare soil imagery (either digital orthophotographs or IKONOS satellite images), and digital soil type maps in combination with destructive soil sampling greatly increased the obtainable precision of soil carbon (C) maps. At all sites, the best techniques increased the relative map precision by about 20 to 25% over commonly used ordinary kriging. A general procedure for post-processing of yield monitor data was developed and tested at two sites. The proposed new procedure involves (i) cleaning of yield monitor data of at least 5 years, (ii) standardization, (iii) interpolation to 4 m x 4 m cells, (iv) averaging across years, (v) classification using fuzzy-k-means or standard cluster analysis techniques, and (vi) post-classification spatial filtering to create yield zones.

IMPACT: 2001/10 TO 2002/09
This project is generating the quantitative understanding needed to fine-tune crop management for achieving yields of at least 70 to 80% of the yield potential under practical conditions. Data have been used to developed a more accurate corn growth model, which is being used to create maps of yield potential and optimal planting dates and hybrid choice for corn as well as assessing key scenarios for soil C sequestration in corn-based systems. Knowledge, methods, and models derived from various ongoing studies will be applied in statewide research on nutrient recommendations for high corn yields across an agroecological gradient in Nebraska. This will lead to improved fertilizer recommendations, including the development of new fertilizer recommendation software. Several new mapping algorithms will have potential impact on improving site-specific crop management.

PUBLICATIONS: 2001/10 TO 2002/09
1. Binder, D.L., A. Dobermann, D.H. Sander, and K.G. Cassman. 2002. Biosolids as nitrogen source for irrigated maize and dryland sorghum. Soil Sci. Soc. Am. J. 66: 531-543.
2. Cassman, K.G., A. Dobermann, and D.T. Walters. 2002. Agroecosystems, nitrogen-use efficiency, and nitrogen management. Ambio 31:132-140.
3. Dobermann, A. 2001. Crop potassium nutrition - implications for fertilizer recommendations. In Proc. of the 31st North-Central Extension-Industry Soil Fertility Conference, November 14-15, 2001, Des Moines, IA. Potash & Phosphate Institute, Brookings, SD.
4. Dobermann, A., T. Arkebauer, K.G. Cassman, R.A. Drijber, J. Lindquist, S. Madhavan, J. Markwell, L. Nelson, J.E. Specht, D.T. Walters, H.S. Yang, B. Amos, D.L. Binder, C. Murphy, and G. Teichmeier. 2002. Corn yield potential and optimal soil productivity in irrigated corn/soybean systems. p. 65-85. In L.S. Murphy (ed.) Proceedings of the 2002 Fluid Forum, Vol. 19. Fluid Fertilizer Foundation, Manhattan, KS
5. Dobermann, A., T.J. Arkebauer, K.G. Cassman, J.L. Lindquist, D.T. Walters, H.S. Yang, B. Amos, D.L. Binder, and G. Teichmeier. 2002. Understanding corn yield potential and optimal soil productivity in irrigated corn systems. p. 260-272. In A.J. Schlegel (ed.) Great Plains Soil Fertility Conference Proceedings, Vol. 9. Kansas State University, Manhattan, KS
6. Dobermann, A., and K.G. Cassman. 2002. Plant nutrient management for enhanced productivity in intensive grain production systems of the United States and Asia. Plant Soil 247:153-175.
7. White, J.D., J.D. Corbett, and A. Dobermann. 2002. Insufficient geographic characterization and analysis in the planning, execution and dissemination of agronomic research? Field Crops Res. 76:45-54.

PROJECT CONTACT:

Name: Dobermann, A. R.
Phone: 402-472-1501
Fax: 402-472-7904
Email: adobermann2@unl.edu

Item No. 13 of 27

ACCESSION NO: 0192056 SUBFILE: CRIS
PROJ NO: NEB-12-290 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 MAY 2002 TERM: 01 DEC 2006 FY: 2002

INVESTIGATOR: Mamo, M.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

RELATIONSHIP OF ORGANIC PHOSPHORUS BIOAVAILABILITY AND PH TO PLANT GROWTH, PHOSPHORUS UPTAKE, AND MYCORRHIZAL ESTABLISHMENT

OBJECTIVES: 1. To assess the dominant cause(s) of surface and subsurface soil acidity under irrigated and conservation management systems of northeast Nebraska. The working hypothesis of this objective is that the extent and severity of soil acidity under irrigated systems on low buffering capacity sandy soils is dependent on management factors, inputs, and soil properties. 2. To determine the bioavailability of common (in soil and manure) organic P compounds for plant uptake at various organic/inorganic P ratios and pH. The working hypothesis of this objective is that the affinity of plants to uptake organic P is dependent on the ratio of organic/inorganic P and the chemical environment (as controlled by pH) of rhizosphere. The degree of hydrolysis depends on the structure of organic Po species and the pH. 3. To quantify corn, soybean, and mycorrhizae responses to pH-induced restricting elements in acidified sandy soil of northeastern Nebraska. The working hypothesis of this objective is that acidification of subsurface soil in Nebraska has resulted in Al and/or Mn levels that restrict root growth thus ensuing in poor P uptake even when P is well supplied. 4. To mitigate surface and subsurface soil acidity using different strategies and modes of application of agricultural lime for conservation and conventional soil management systems and improve P uptake efficiency. The working hypothesis of this objective is that efficacy of liming material to remediate soil acidity and P uptake depends on source (i.e., various liming materials) and characteristic of liming and ability of liming to reach subsoil.

APPROACH: The objective of this first experiment is to assess the predominant cause(s) of surface and subsurface soil acidity under irrigated and conservation management systems of northeast Nebraska. The working hypothesis of this objective is that there is high soil pH variability in the field due to management, landscape position, and parent materials. The survey will be on two major cropping systems, with two N fertilizer placement method, and three soil-landscape positions managed with conservation tillage system. Soil will be sampled to a depth of 30-cm at depth increment of 8-cm. Soil samples will be analyzed for pH, extractable aluminum and manganese and lime requirement. In addition to the management history and fertilizer type, relevant information such as fertilizer rate, years of fertilizer application, and historic yield will be included in the database for each sampling site if available. The objective of this second experiment is to determine the bioavailability of common (in soil and manure) organic P compounds for plant uptake at various organic/inorganic P ratios and pH. The working hypothesis of this objective is that the affinity of plants to uptake organic P is dependent on the ratio of organic/inorganic P and the chemical environment (as controlled by pH) of rhizosphere. The experiment will be done in the greenhouse using sandy soils at various pHs. In this study, all essential nutrients (except P) as recommended by a soil test will be added to the soils. The recommended rate of P will be supplied at different ratios of inorganic and organic P. Corn and soybean, will each be grown in the soil and plant P uptake, uptake efficiency, root surface area, phosphatase activity, and mycorrhizal colonization will be measured. The objective of this third experiment is to quantify corn, soybean, and mycorrhizae responses to pH-induced restricting elements in acidified sandy soil. Soil collected from farmer's fields will be used to mimic the field soil acidification gradient and profiles of Al or Mn. Root surface area, above ground plant biomass, mycorrhizal development, soil solution chemistry, and nutrient uptake of corn and soybean grown on sandy soil will be measured. The objective of this fourth experiment is to mitigate surface and subsurface soil acidity using different strategies and modes of application of agricultural lime for conservation and conventional soil management systems. The working hypothesis of this objective is that efficacy of liming material to remediate soil acidity and P uptake depends on source (i.e., various liming materials) and characteristic of liming and ability of liming to reach subsoil. Soil collected from farmer's fields will be used to mimic the field soil acidification gradient and profiles of Al or Mn. The soil will be limed in three different strategies (no-till, reduced tillage, and conventional tillage). Root surface area, above ground plant biomass, mycorrhizal development, soil solution chemistry, and nutrient uptake of corn and soybean grown on sandy soil will be measured.

NON-TECHNICAL SUMMARY: Management-induced surface and subsurface soil acidity (i.e., long-term N fertilization) is a potential threat to sustainable production and yield potential. The causes threatening production may be associated with toxic levels of Al and Mn, or due to depletion or unavailability of P and other essential nutrients. This research will attempt to understand how soil acidity affects soil solution chemistry, P uptake, and mycorrhizal infection/colonization.

PROGRESS: 2001/10 TO 2002/09
Two sites have been selected based on soil textural class (coarse and fine texture) and P levels. These soils have low soil test P levels (< 7 ppm) and will be used to conduct greenhouse studies. In addition, a soil from northeastern Nebraska with stratified soil pH and Al levels has been collected. Preliminary experiments have been established in the greenhouse to evaluate the effect of organic to inorganic P ratios on corn P uptake, corn root characteristics, mycorrhizal infection, and soil P fractions. These results will help refine future laboratory and field experiments.

IMPACT: 2001/10 TO 2002/09
At the completion of this study, it is expected that we will understand the relationship between soil acidity and the ability of mycorrhizae to infect roots. We expect that soil acidity will strongly influence root characteristics, which will in turn, impact the ability of mycorrhizae to thrive. The limited availability of mycorrhizae will coordinately reduce the bioavailability of phosphorus, due to decreased root-fungi interactions. These studies will help fine tune P management by improving P availability to plants and reducing loss of P to the environment.

PUBLICATIONS: 2001/10 TO 2002/09
No publications reported this period

PROJECT CONTACT:

Name: Mamo, M.
Phone: 402-472-8493
Fax: 402-472-7904
Email: mmamo3@unl.edu

Item No. 14 of 27

ACCESSION NO: 0192330 SUBFILE: CRIS
PROJ NO: NEB-12-291 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUL 2002 TERM: 30 JUN 2007

INVESTIGATOR: Wortmann, C. S.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

IMPROVED SOIL PRODUCTIVITY AND ENVIRONMENTAL QUALITY ON NON-IRRIGATED LAND IN SOUTHEASTERN NEBRASKA

OBJECTIVES: Objective 1. Determine properties and management practices of manure and soil which affect the agronomic benefits and environmental risks of manure application. Hypotheses 1. The residual effect of manure applied in previous years will result in less runoff than where no manure was previously applied, but high P concentrations and more total P in the runoff. Hypothesis 2. Yield response is greater on sloping land where surface soil is relatively high in clay while low in available P and organic matter, as compared to other field positions and soil properties. Objective 2. A decision aid will be developed for profitable use of starter fertilizers under no-till conditions on once eroded hillsides of eastern Nebraska. Hypothesis 1. 2x2 placement of starter fertilizer will be sufficiently effective under some no-till conditions (e.g. when surface soil P is stratified) to justify the added cost as compared to over-the-row placement. Hypothesis 2. Corn and sorghum response to S applied in starter fertilizer will be profitable when no-till soils have less than 2% OM. This is more likely if the aspect is northerly. Objective 3. Improve the basis for N management for grain sorghum production. Hypothesis 1. The soybean N credit to sorghum is considerably greater than 50 kg ha-1. Hypothesis 2. The late season soil nitrate test and amino sugar tests are useful in estimating N fertilizer need for sorghum. Hypothesis 3. Grain sorghum N, P and K requirement can be determined from a generic basis (e.g. QUEFTS) whereby grain yield and seed number are related to plant N concentration and uptake, and N harvest index.

APPROACH: Obj. 1. Hypotheses 1 will be tested using a runoff facility with 21 plots as a continuation of a 3 year study of the effects of seven manure treatments on P losses to surface water during the season of application. Comparisons included high vs. low P manure, winter vs. spring application, and incorporated vs. surface application. The cattle manures were applied annually to supply 200 kg plant available N ha-1 for 3 consecutive years until Febr. 2001. Treatment 7 received fertilizer N only. The residual effects of the manure treatments will be studied for two years with no additional manure applied. Observations include: 1. Surface soil for: total N and C; P by Bray1 and Fe-oxide strip (BAP) method; nitrate-N; and ammonium-N. 2. Deep soil samples for nitrate-N. 3. Runoff for: volume and suspended sediment concentration. 5. Unfiltered runoff for: BAP; total N and P. 6. Filtered runoff for: NH4-N and NO3-N; dissolved P and BAP. 7. Plant biomass, grain and residue N and P, grain yield. Analysis of variance (repeated measures) will be conducted. Results will be further explored and interpreted using a model for non-point source nutrient movement. The results will be used to improve tools for assessing land potential for P runoff. Hypothesis 2 will be tested with farmer managed trials laid out in long strips across rolling fields. The treatments are: manure applied to supply corn N needs; and a fertilizer treatment. There will be an average of 2.5 observation points per rep to take advantage of variations in soil properties, 5 reps per field, and 12 fields. The trials will be harvested with yield mapping equipment where feasible; otherwise hand harvests of 10 m2 areas will be made at the observation points. The effects of manure, as compared to fertilizer, on crop yield will be determined and related to soil and landscape properties. A decision guide to zone-specific application of manure will be developed. Obj. 2. Two or 3 trials will be conducted per farmer's field at different topographic positions/soil types with 12 and 15 trials of 4 reps conducted for sorghum and corn, resp.. Treatments include: no starter applied; N+P (20 + 20 lb) applied 2x2, over-the-row, and in the seed furrow (10 + 10 lb); N+P+S (20 + 20 + 10 lb) applied 2x2, over-the-row, and in-furrow (10 + 10 + 5 lb). In-furrow application of S as ATS will be compared to NH4 sulfate. Farmers will apply sufficient N fertilizer to achieve expected yields. Observations: soil P and NO3-N; soil temperature; plant count and early biomass and nutrient uptake; grain yield and final plant stand; N and P uptake; harvest index. Effects of placement and fertilizer type will be interpreted considering soil temperature, organic matter, aspect, soil P level, and P stratification. Obj. 3. On-farm trials (12) will be conducted to test these hypotheses. Treatments include: 0 N; full N rate according to UNL recommendations; full rate minus 50 kg N; full rate minus 75 kg N. Fertilizer N will be surface-applied NH4-NO3 after planting. Observations include: yield, nutrient uptake and HIs. This data will be integrated with data from Africa and other trials to test hypothesis 3.

NON-TECHNICAL SUMMARY: Agricultural lands and animal feeding operations are sources of pollutants contaminating large and small water bodies. This project examines alternatives for more efficient use of fertilizer and livestock manure to improve the profitability of crop production in southeast Nebraska while reducing non-point source pollution.

PROGRESS: 2002/07 TO 2002/09
Project just began; therefore, no progress to report.

PUBLICATIONS: 2002/07 TO 2002/09
No publications reported this period

PROJECT CONTACT:

Name: Wortmann, C. S.
Phone: 402-472-2909
Fax: 402-472-7904
Email: cwortmann2@unl.edu

Item No. 15 of 27

ACCESSION NO: 0194934 SUBFILE: CRIS
PROJ NO: NEB-12-293 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW MULTISTATE PROJ NO: NC-218
START: 01 OCT 2001 TERM: 30 SEP 2006 FY: 2002

INVESTIGATOR: Walters, D. T.

PERFORMING INSTITUTION:
AGRONOMY
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

ASSESSING NITROGEN MINERALIZATION AND OTHER DIAGNOSTIC CRITERIA TO REFINE NITROGEN RATES FOR CROPS AND MINIMIZE LOSSES

OBJECTIVES: 1. Develop and evaluate rapid tests for soil N mineralization capacity across the various soils and climatic regimes of the region and determine the feasibility and most appropriate conditions for use of these tests. 2. Conduct fundamental work to enhance current understanding of the role of active C and N pools in cropping systems and to predict net N mineralization as influenced by C sequestration management. 3. Develop a guidance document for agricultural professionals focusing on N best management practices and optimum rate determinations for the region.

APPROACH: A common field design and a centralized analytical laboratory approach will be used to accomplish the stated objectives. The field component of the project will involve installation of N response experiments at sites representing the soils and cropping systems used for corn production in states of the north central region. Soil sampling at each site will be done prior to planting in the spring. Samples will be collected for nitrate N to quantify soil residual nitrate N contribution to crop N supply. In addition, samples will be analyzed for new and exzisting tests for N mineralization. These will include the amino sugar test, aerobic incubation, arylamidase activity and microbial biomass C and N. Relationship among diagnostic tests to observed optimum N rate, N use efficiency and potential for nitrate leaching will be studied using regression techniques. Soils will also be studied to assess the influence of C dynamics on N mineralization and availability. Physical fractionation of soil organic matter will be done to evaluate SOM fractions with greatest biological significance especially to N availability. In addition, chemical fractionation of mobile and calcium humic acid fractions will be evaluated in time series to monitor the impact of cropping sequence on both C and N sequestration on these organic matter pools. Finally data from the proposed project and from previous projects conducted by the NC-201 and NC-218 committees will form a database for a guidance document to be prepared as a committee activity. This database will contain about 500 site-years of experimental data to prepare a summary of current approaches to N best management practices for corn in the region. Information available from this regional database will provides an ideal opportunity to investigate combinations of the exhaustive range of tests and procedures evaluated by the committee to construct a process involving the most effective procedures for predicting N availability across the diverse conditions of the region or in sub-regions having similar soil, climatic, and crop production conditions. This would address the identified information need to explore the possibility that a combination of tests has greater and more broadly applicable potential for predicting N availability than any single method.

NON-TECHNICAL SUMMARY: Nitrate enrichment of ground and surface waters and its impact on water quality and hypoxia in the Gulf of Mexico are important environmental issues. Nitrogen use in maize cropping systems in the north central region is one of the major sources of nitrate entering natural waters. This project will examine the role of active soil carbon and nitrogen pools in predicting nitrogen behavior.

PROJECT CONTACT:

Name: Walters, D. T.
Phone: 402-472-1506
Fax: 402-472-7904
Email: dwalters1@unl.edu

Item No. 16 of 27

ACCESSION NO: 0164320 SUBFILE: CRIS
PROJ NO: NEB-42-020 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 18 MAR 1994 TERM: 30 NOV 1999 FY: 2000

INVESTIGATOR: Kranz, W. L.

PERFORMING INSTITUTION:
NORTHEAST RES & EXTENSION CNTR
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

EFFECTS OF PREPLANT TILLAGE AND NITROGEN APPLICATION METHOD ON NITRATE LEACHING

OBJECTIVES: 1. Ascertain the influence of preplant tillage on total nitrogen leaching loss &loss via preferential flow pathways. 2. Determine the impact of nitrogen application method of leaching loss. 3. Evaluate the interaction between preplant tillage and nitrogen application for soil leaching loss. 4. Examine the distribution & continuity of preferential flow pathways using image analysis.

APPROACH: Large undisturbed soil monoliths (1 cubic meter) were excavated from field plotswith 15 years of tillage history. Soil monliths were obtained from 3 replications of 3 tillage treatments-moldboard plow + harrow, chisel, & ridgetill. Conservative tracers will be used to simulate nitrogen applied with water, surface broadcast, & slot + compaction. A rainfall simulator will apply water at a 25 mm/hr rate during 2 events. Event 1 will simulate 10 year storm for central Iowa and Event 2 will bring the total water applied to near 1.5 pore volumes. Soil water content will be monitored at 15, 20, 35, 65, and 90 cm below the soil surface using time domain reflectometry. Minitensiometers will be placed adjacent to the TDR waveguides. Readings will be recorded at 15 minute intervals throughout the simulation events. Leachate samples will be collected from a 54 cm square area on the bottom of the monolith using fiberglass wick extractors. Wick extractors will be placed in a 6 x 6 grid arrangement. Following simulation runs the soil will be disected at 10 cm intervals for video imate analysis of macropores.

NON-TECHNICAL SUMMARY: Corn producers use some preplant tillage and nitrogen fertilizer application method combinations that may contribute to nitrate leaching losses. The purpose of this project is to determine which combination of preplant tillage and nitrogen fertilizer application method minimizes nitrate leaching losses from cropland. If successful, producers can use practices that limit contamination of groundwater and surface water.

PROGRESS: 1994/03 TO 1999/11
Nitrogen application was simulated by applying conservative tracers to one meter cubic soil blocks removed from plot areas with 15 years of tillage and cropping history. Tracers were applied to simulate surface broadcast, slot with surface compaction, and with water. A fiberglass wick extraction system was used to collect leachate in a 6 x 6 square grid arrangement. Data analysis suggested that low level surface compaction was not sufficient to direct water around a tracer application zone. Water flow may need to be directed away from the application zone by mounding or doming soil over the application zone in addition to compaction over the area. Because the slot applied tracer was concentrated in a narrow band, leaching loss curves indicated greater losses directly below the application zone regardless where the greatest water losses were recorded. This means that water was not directed around the zone of application effectively. For broadcast applications, nitrate-nitrogen loss was determined by water collections at each grid cell for each water application. After block collection procedures were completed, it was determined that the field area contained soils from three mapping units. These soils have slightly different profiles that may have impacted leaching loss results.

IMPACT: 1994/03 TO 1999/11
For these soil conditions, a) Substantial soil compaction will be necessary to direct infiltrating water around a zone of chemical application. Soil mounding or doming may also be required. b) Variation in small-scale soil properties mask the impact of cultural practices even after 15 years of consistent treatments. c) Additional research is needed to verify the true impact of nitrogen application methods on nitrogen leaching.

PUBLICATIONS: 1994/03 TO 1999/11
No publications reported this period

PROJECT CONTACT:

Name: Kranz, W. L.
Phone: 402-370-4012
Fax: 402-370-4010
Email: wkranz1@unl.edu
URL: http://www.ianr.unl.edu/ianr/nerec/Bill Kranz.htm

Item No. 17 of 27

ACCESSION NO: 0181121 SUBFILE: CRIS
PROJ NO: NEB-42-024 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 FEB 1999 TERM: 31 JAN 2004 FY: 2002

INVESTIGATOR: Shapiro, C. A.

PERFORMING INSTITUTION:
NORTHEAST RES & EXTENSION CNTR
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

UTILIZING ANIMAL MANURES & FERTILIZERS IN CROPPING SYSTEMS FOR NORTHEAST NEBRASKA

OBJECTIVES: 1. Determine the impact of growing season weather on the nitrogen use efficiency of corn grown under spring plow, disk & no-till in a continuous corn & a corn-soybean rotation. 2. Quantify the relative N use efficiency of alternate row nitrogen fertilization and site specific N application in furrow irrigation. Determine the net benefit of alternative row fertilization when yield and potential N leaching are taken into acccount. 3. Determine the effect of rate of swine effluent irrigation on the nitrogen harvest, drymatter yield, soil nutrient concentration and nitrate leaching in alfalfa and a corn-rye system. Calculate loading limits to maintain groundwater quality. 4. Determine the effect of swine and beef manure application on nitrate release, soil phosphorus, and soil organic carbon level.

APPROACH: Established experiments will be continued for objectives 1 and 2. (1) Corn is grown in roation with soybeans under annual tillage of spring moldboard plow, disk & no-till with five N rates. Spring soil moisture & nitrate content will be used to calibrate growth models. Models will be adjusted for tillage & rotation factors. (2) Alternate row irrigation will be tested under production furrow irrigation. Rows will be irrigated in every row or every other row. Nitrogen will be applied in every row or under alternate row irrigation in the dry rows. Nitrate in the fall will be determined & crop yield. (3) Anaerobic lagoon swine effluent will be used as the water source to irrigate corn & alfalfa. Porous cup samplers will be used to catch leachate below ground. Optimum effluent rates will be determined so that leachate remains below 10 ppm. (4) Swine & beef manure will be compared for N release & change in organic matter. Low organic carbon sites will be selected with non or slight manure history. Changes will be monitored through the season.

PROGRESS: 2001/10 TO 2002/09
Six corn hybrids were grown in 2001 on a low potassium sandy site, testing under 100 ppm extractable K, at three K rates (0, 75, 150 lbs K2O/acre). Stalk strength ranked on a relative scale ranged from poor to good, 3-7 on a 9 point scale. Grain yield was not affected by K application. This maybe due to variability in soil K levels, by replication gradients, and by soil depth. Soil samples were taken from each experimental unit at 0-6, 6-12, and 12-24 inches and document subsurface variability. Although surface soil K levels were low, profile K levels were sufficient to provide K to the corn. Differences in stalk moisture at physiological maturity and harvest were found for some hybrids. Maintaining stalk moisture during grain drydown may be related to stalk strength and resistance to lodging. In another study, three years of field studies evaluated the effects of manure, corn hybrid (root ratings) and reduced insecticide rates on corn rootworm larval (Diabrotica virgifera virgifera LeConte and Diabrotica barberi Smith) injury and corn yield. Manure rates were 0, 67, 133 MT/ha and 0, 2.8, 5.6, and 11.2 g (AI)/100 m-row terbufos 15G. Manure reduced root injury 7 to 11% and increased yield 1 to 8%. Insecticide reduced root injury ratings but did not affect yield. When manure was applied without insecticide application, root injury was reduced 11 to 16%. Manure did not affect efficacy of the insecticides. Hybrid tolerance as measured by root strength ratings did not affect damage ratings or corn yield.

IMPACT: 2001/10 TO 2002/09
The relationship between potassium fertilization, soil potassium levels and corn stalk strength and yield is more complicated than simply determining a soil critical level. Both application of potassium fertilizer and hybrid selection may need to be fine-tuned in the future to reduce the potential for stalk lodging between physiological maturity and harvest time. Manure application was shown to have some positive affect on reducing the severity of corn rootworm feeding in the absence of insecticide. However, it did not substitute for insecticide and did not improve the effectiveness of reduced insecticide rates. It did not interfere with insecticide effectiveness.

PUBLICATIONS: 2001/10 TO 2002/09
Shapiro, C.A., G.W. Echtenkamp, J.F. Witkowski, and T.E. Hunt. 2002. Effects of manure, hybrid tolerance, and reduced rates of insecticide on corn rootworm (Coleoptera: Chrysomelidae) injury to corn. Journal of Sustainable Ag. In Press.


Item No. 18 of 27

ACCESSION NO: 0182310 SUBFILE: CRIS
PROJ NO: NEB-43-067 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUN 1999 TERM: 31 MAY 2004 FY: 2002

INVESTIGATOR: Clark, R. T.

PERFORMING INSTITUTION:
WEST CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

ECONOMIC AND NITRATE LEACHING IMPLICATIONS OF WATER CONSERVATION IN NEBRASKA IRRIGATED AGRICULTURE

OBJECTIVES: 1) Quantify the effects of alternative irrigation and fertilizer management strategies on crop yields and potential nitrate leaching; 2) Determine maximum-net-revenue quantities of applied irrigation water and fertilizer under various economic and policy conditions, for several cropping strategies and soil types; and 3) Identify efficient risk strategies for and tradeoffs among producer net revenue, irrigation water use, and nitrate leaching potential associated with varying input and output prices and climatic conditions.

APPROACH: The task of Objective 1 is to develop irrigated crop response models for major crops in the Republican River Basin in Nebraska. This objective will be met through analysis of agronomic data from three sources: 12-year experimental study of limited irrigation at University of Nebraska/North Platte , on-going six-year Limited Irrigation Demonstration Project, and recent survey information from the irrigators in southwest Nebraska, who operate with well meters and a yearly 14.5 acre-in/acre allocation. Separate production functions for each crop will be estimated with regression analysis using the three sets of data. The results will be compared and validated. The functions will include factors such as: applied water, nitrogen fertilizer, effective rainfall, beginning of season stored soil water, and soil water-holding capacity. The timing of water applications will also be considered. In addition to estimating response functions, similar techniques will be used to estimate equations for nitrate leaching as functions of water, fertilizer use and other variables. Levels of residual soil nitrates have been measured through lysimeters in the experimental plots at North Platte for 10 years. Data are lacking for soils in the lower River Basin and will be generated through a crop simulation program, such as EPIC (USDA/ARS) or CropSyst (Washington State University). Both models can simulate crop rotations and N leaching beyond the root zone under various climatic and management conditions. In Objective 2, maximizing net revenue (or profit) per acre for each crop will be done by solving a nonlinear optimization problem (with different price and weather conditions) for optimal levels of applied water and fertilizer (for a given irrigation management/soil type/crop rotation scenario). If water use is restricted through limited pumping capacity or mandated allocations, the problem becomes a constrained optimization model. The solution to the constrained problem will enable us to determine the opportunity cost or "shadow price" of an additional acre-inch of allocated water. In a separate model, we will also solve for the most profitable allocation of water, fertilizer, and land among the four crops being studied when allocations are set at 4, 6, 8, 10, 12, and 14 inches/acre. In Objective 3, cumulative probability functions of net returns (by soil type) will be estimated for management/soil/crop rotation scenarios considered in Objective 2. Stochastic efficiency analysis will be used to rank the various scenarios. The risk analysis will include variations in weather, input prices and output prices over a 20-30 year period. A similar method will be used to look at risk of nitrate leaching for various management/soil type scenarios. Additionally, an analysis of the potential trade-offs between net revenue and water conservation/quality will also be performed. This information, via a non-stochastic frontier function, will illustrate under what conditions producers can achieve significant savings in water (and reductions in nitrate leaching) for a small loss in net revenue.

NON-TECHNICAL SUMMARY: Declining river flows and groundwater tables threaten the future of irrigated agriculture in parts of Nebraska. Irrigation increases the likelihood of nitrate water pollution problems. This project examines the role of limited irrigation management in sustaining profitable crop production and decreasing nitrate leaching, when water supplies are restricted.

PROGRESS: 2001/10 TO 2002/09
Data from 6 years of on-farm research/demonstration projects with 4 water treatments are being summarized and analyzed. The four treatments: 1) farmer directed irrigation; 2) best management practice (irrigate by soil-water budgets); 3) late initiation (start needed irrigation after vegetative stage); and allocation (upper limit on water available for irrigation for season). Preliminary results show that corn yields on higher water holding capacity soils are reduced some (average 7%) from the lower irrigation application when that application is timed to coincide with critical times in grain production. Corn yields on sandier, lower water holding capacity soils are impacted much more by the reduced irrigation strategies (about 15% lower for allocation versus farmer directed or BMP). Water use on the other hand was significantly reduced on all soil types for the allocation compared to farmer directed (50%). Allowing for pumping costs and yield differences, producers on average would net about $25/acre less if they followed the allocation treatment, and only $3/acre less with the late initiation treatment compared to farmer directed.

IMPACT: 2001/10 TO 2002/09
Water conservation management practices can reduce irrigation water by up to 50% with a maximum of $25/acre loss in net returns (corn at $2/bushel and irrigation water at $2.50/inch applied). Other intermediate strategies such as late initiation of irrigation reduce water use by about 30% and net returns by only about $4/acre.

PUBLICATIONS: 2001/10 TO 2002/09
No publications reported this period

PROJECT CONTACT:

Name: Norton, N. A.
Phone: 308-532-3611
Fax: 308-532-3823
Email: nnorton1@unl.edu

Item No. 19 of 27

ACCESSION NO: 0184435 SUBFILE: CRIS
PROJ NO: NEB-43-068 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 NOV 1999 TERM: 31 OCT 2004 FY: 2002

INVESTIGATOR: Hergert, G. W.

PERFORMING INSTITUTION:
WEST CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

IMPROVING FERTILIZER MANAGEMENT AND RECOMMENDATIONS FOR PRECISION AGRICULTURE

OBJECTIVES: 1. Develop site specific N fertilizer recommendation algorithms for corn that more accurately predict optimum N rates than past or current models. 2.Develop site specific P fertilizer recommendation algorithms for corn and compare the economics of continuous functions versus tabular valuesfor fertilizer P . 3.Compare seed row-applied Fe fertilizer treatments and tolerant corn hybrids on high pH conditions and develop chlorosis severity maps of fields using aerial photography, soil pH, chlorophyll meter readings and spectral radiometer techniques to improve yields and profitability on high pH soils.

APPROACH: Objective 1: Different regression procedures (stepwise forward and backward using quadratic, cubic plus linear and quadratic plateau models) were used to develop the current NE corn N recommendation algorithm. This information will be published to explain how the current algorithm was developed. Contrasts of the improved prediction of new algorithm compared to past recommendations will be investigated. Additional data from the Platte Valley mineralization project (1991-1995)and N rate experiments from corn-soybean rotations (R.B. Ferguson,1988 -1991) will be included to develop an expanded Nebraska data base of over 200 site years. Additional N rate experiments will be conducted to add landscape position sites not in the data base. The experimental design will be a RCB with field length strips. PROC MIXED will be used to analyze data. Data will be sorted by soils, regions or agroecological zones to compare site specific algorithms to one large inclusive model. Alternative regression models and approaches will be used to develop algorithms and compare their economic impact. Objective 2. Past P experiment data sets will be centralized into a data base with recent research work. Regression techniques will be used to develop different P recommendation models. Continuous function P recommendation algorithms will be compared to recommendations in current tabular form to determine the economic advantage of continuous versus tabular `step' data on the economics of P use. Objective 3. Soil areas with known chlorosis severity will be used to compare different seed row applied iron treatments using high pH tolerant and susceptible hybrids. Yield trials will be conducted on high pH and more neutral soil pHs to see if genotypic and Fe fertilizer combinations display significant pH by hybrid by Fe fertilizer interactions. Fertilizer materials will include iron chelate (FeEDDHA), iron sulfate, and available experimental products. Treatments will include seed-applied materials and foliar applications of iron sulfate and iron chelate. Chlorophyll meter readings (taken 2 or 3 times/season) and final grain yields will be taken to determine treatment effect. Correlations of soil parameters, chlorophyll meter readings and final grain yield will be determined. Aerial photography, soil pH, and other soil characteristics will be used to develop chlorosis severity maps of farmer fields that exhibit chlorosis. Different interpolation techniques (kriging, inverse distance, and tinning) will be used to develop maps that can be compared to on-nadir aerial photographs that will be scanned into a GIS. Yield maps of these fields will also be compared in the GIS for the different method to determine chlorosis severity to develop the most powerful predictive tool or index for determining hybrid-Fe treatment combinations. Replicated small plot trials using RCB designs will be used to screen materials and hybrids. Farmer who have chlorosis problems and yield monitors will be asked to cooperate in a full-field experimentation phase.

NON-TECHNICAL SUMMARY: Current NE fertilizer recommendations are not soil or site specific. Past, current and future data need to be reanalyzed and reinterpreted to develop new fertilizer recommendations. The purpose of the research is to develop site specific fertilizer recommendations that improve farm profitability while reducing effects on the environment.

PROGRESS: 2001/10 TO 2002/09
Work on site-specific N management for irrigated corn showed that site-specific N management for corn did not decrease the amount of N fertilizer applied and yields were not significantly different most years. The spatial application of N based on the existing N recommendation algorithm did not improve N use efficiency compared to uniform application. There were no significant differences between uniform management (UM) compared to variable rate technology (VRT) application on residual soil nitrate-N. A Reduced VRT N application showed lower soil residual nitrate-N but did not always produce lower yield than the normal VRT application. The study suggests that improved recommendation algorithms may need to be combined with other sensing methods to monitor crop N status followed by carefully timing and spatially adjusted supplemental N fertilization to achieve optimum N-use efficiency. Data from an 81 site data base will be combined with other state-wide N rate studies to expand the data base. During the next years we will develop criteria for agro-ecoregion or soil series-based recommendations. Experiment conducted from 1995 to 1999 on silt loam soil (pH 8.6) with a history of severe Fe chlorosis applied iron fertilizers to a chlorosis tolerant and a non-tolerant maize hybrid. Fertilizer materials included a foliar application of a FeSO4-7H2O solution, seed-row applications of dry FeSO4-7H2O, FeEDDHA, Fe oxysulfate and an experimental FeSO4-7H2O-suspension. The tolerant hybrid consistently produced higher yields than did the non-tolerant hybrid regardless of fertilizer treatment. Dry FeSO4-7H2O produced the highest yields with an application rate of 22 kg Fe per ha producing the most consistent economic yield increases. The results suggest the importance of hybrid selection and seed row applications of Fe fertilizers to manage Fe chlorosis. Laboratory research compared phytosiderophore release from nodal, primary and complete root systems of tolerant and non-chlorosis tolerant maize hybrids. In early experiments an Fe-efficient hybrid (P3279) released more phytosiderophore from nodal roots than an Fe-inefficient hybrid (P3489). Tests of an additioonal 10 hybrids did not clearly distinguish between efficient and non-efficient lines. Nodal roots, however, showed more promise in quantifying and differentiating phytosiderophore release. Work is on-going to correlate field symptom severity with phytosiderophore release.

IMPACT: 2001/10 TO 2002/09
Improved N recommendations from site-specific N recommendations should improve profitability and N use efficiency expecially in irrigated areas. Proper hybrid selection and site specific Fe fertilizer application could increase yields and profits on high pH soils by $30 to $40 per acre.

PUBLICATIONS: 2001/10 TO 2002/09
1. Ferguson, R.B., G.W. Hergert, J.S. Schepers, C.A. Gotway, J.E. Cahoon and T.A. Peterson. 2002. Site-specific nitrogen management of irrigated maize: Yield and soil residual nitrate effects. Soil Sci. Soc. Am J. 66:544-553.
2. Bernards, Mark L., Von D. Jolley, W.Bart Stevens and Gary W. Hergert. 2002. Phytosiderophore release from nodal, primary and complete root systems in maize. Plant and Soil 241: 105-113.

PROJECT CONTACT:

Name: Hergert, G. W.
Phone: 308-532-3611-128
Fax: 308-532-3823
Email: ghergert1@unl.edu

Item No. 20 of 27

ACCESSION NO: 0190826 SUBFILE: CRIS
PROJ NO: NEB-43-069 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 SEP 2001 TERM: 01 DEC 2003 FY: 2002

INVESTIGATOR: Payero, J. O.; Ensley, S.; Hergert, G. W.

PERFORMING INSTITUTION:
WEST CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

ENVIRONMENTAL IMPACT OF LAND APPLICATION OF ANIMAL MANURE AS FERTILIZER FOR IRRIGATED CORN

OBJECTIVES: 1) To determine the vertical rate of transport of antibiotics and nitrate resulting from land applications of cattle manure used as a fertilizer source in irrigated corn. 2) To determine if the presence of antibiotics in the manure will result in the development of antibiotic-resistant bacteria in the soil and groundwater.

APPROACH: The experiment will be conducted at the WCREC lysimeter site in North Platte, NE, during a two-year period (starting in 2002), using a Completely Randomized Design with three treatments and four replications. Treatments include the application of: (1) chemical fertilizer at 100% agronomic nitrogen rate (control treatment), (2) cattle manure at 80% agronomic nitrogen rate, and (3) cattle manure at 100% agronomic nitrogen rate. The Nitrogen sources will be applied pre-plant every year. Agronomic nitrogen rate and the amount of manure to apply will be determined based on soil and manure tests. All treatments will be fully irrigated using a solid-set sprinkler irrigation system and following best management practices for irrigation scheduling. In each plot, a cylindrical percolation lysimeter is installed (8-ft deep and 3 ft in diameter). Porous extractors at the bottom of the lysimeters allow extracting leachate from unsaturated soil using a vacuum pump. The leachate from the lysimeters will be collected weekly and analyzed for the presence and concentration of nitrate and antibiotics. The presence of antibiotics will be determined using commercially available ELISA kits, which are sold as screening tools for antibiotics in milk and meat products. These kits will be modified and optimized for the analysis of antibiotics in water and soil samples. If antibiotics are present, then the concentration will be determined using High Performance Liquid Chromatography with Mass Spectrometric Detection (HPLC/MS). The development of antibiotic resistance will be determined by analyzing soil and water samples using a broth dilution method.

NON-TECHNICAL SUMMARY: This project is needed because of the continued expansion in the number of large cattle production facilities in the state, the common use of cattle manure as fertilizer, and the potential implications of these practices on human health, considering that groundwater is the source of drinking water for nearly all Nebraskans. This project will measure the leaching of antibiotics and nitrate resulting from application of cattle manure as a fertilizer for irrigated corn and will evaluate the potential development of antibiotic-resistant bacteria.

PROGRESS: 2001/10 TO 2002/09
The objectives of this project are: (1) to determine the rate of transport of antibiotics and nitrate resulting from land applications of cattle manure used as fertilizer for irrigated corn, and (2) to determine if antibiotics present in the manure will result in the development of antibiotic-resistant bacteria. Cattle manure from animals treated with 75 mg oxytetracycline per head per day was applied pre-plant to irrigated corn plots in April, 2002. Treatments included the application of two rates of manure or chemical nitrogen fertilizer. The manure treatment included application of manure to meet the nitrogen needs of the corn, and double this amount. Treatments were replicated four times and were arranged in a completely randomized design. Each plot had a percolation lysimeter that allowed extracting water leached below the root zone. A concentration of tetracyclines of approximately 3000 ppb was detected in the manure prior to application. Manure was hand applied and incorporated by disking. Background soil samples from the plots and lysimeters were collected at 1-ft increments to a depth of 6 ft before spplying the manure. Soil samples from the plots were taken approximately every 3 weeks thereafter. Lechate samples from the lysimeters were collected weekly. Soil samples were taken at depths of 0-2, 2-4 4-6, 6-14, and 14-24 inches to assess the downward movement and microbial effects of tetracyclines. To follow the movement of nitrate, samples were taken at 1-ft increment to a depth of 6 ft. Soil and water samples were analyzed to determine the presence and concentration of tetracyclines and nitrate, and to assess the development of antibiotic resistant bacteria. To minimize cost, the concentration of tetracyclines was determined using a two-step process. The first step consisted in determining if tetrcyclines were present in the sample. The inexpensive Enzyme-Linked Immunosorbent Assay method was used for this purpose. If tetracyclines were present, their concentrations were determined using the more accurate Liquid-chromatography-tandem mass spectrometry method. To assess antibiotic resistance, samples were analyzed using a procedure that involves several steps. First, DNA from the bacteria population in the samples is extracted using the UltraClean Mega Soil DNA kit (Mo Bio, Salona Beach,CA). Then, since the amount of DNA extracted from the sample is usually too small, the extracted DNA is amplified using the Polymerase Chain Reaction (PCR) method. This step includes the addition of a gene sequence primer that has been identified as indicative of tetracycline resistance. Finally, the gene sequences in the amplified DNA mixture are separated using gel electrophoresis. If the gene sequence in the DNA sample matches the gene sequence of the primer, it can be concluded that the bacteria population in the sample contains tetracycline resistance genes. At the time of this report, we are still planning to sample one more time, after harvesting the crop. We are still in the process of conducting the laboratory analyses stated above. When completed, the data will be analyzed, summarized, and a more complete report will be prepared.

IMPACT: 2001/10 TO 2002/09
There is increasing concern that antibiotics contained manure applied to soils can remain active in the soil and eventually move to the groundwater. If antibiotics persist in soil, there is also the potential for the development of "super bugs" or antibiotic resistant bacteria, which may later produce diseases that are difficult to control in either animals or humans. Finding other ways to dispose of the manure or restricting the use of antibiotics in animal production, however, could have a significant economic impact on producers. As an outcome of this research, we expect to establish how long tetracyclines persist in the soil after application, how fast tetracyclines and nitrate move though the soil profile, and the extend to which resistant genes in the bacteria population present in the soil result from the exposure to tetracyclines. This is significant because application of this new knowledge will allow us to decide if the application of animal manure to croplands can potentially impact animal and human health. If our results show that the effects of tetracyclines are minimal, the current practices could be maintained. Otherwise, steps to alleviate potential problems may need to be taken, such as establishing legislation restricting the use of antibiotics in animal production or modifying the manure before it is applied.

PUBLICATIONS: 2001/10 TO 2002/09
No publications reported this period

PROJECT CONTACT:

Name: Payero, J. O.
Phone: 308-532-3611
Fax: 308-532-3823
Email: jpayero2@unl.edu

Item No. 21 of 27

ACCESSION NO: 0192409 SUBFILE: CRIS
PROJ NO: NEB-43-071 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUN 2002 TERM: 31 MAY 2007 FY: 2002

INVESTIGATOR: Payero, J. O.

PERFORMING INSTITUTION:
WEST CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

IMPROVING IRRIGATION MANAGEMENT TO CONSERVE WATER RESOURCES IN WEST CENTRAL NEBRASKA

OBJECTIVES: This project has the following objectives: (1) conserve water and reduce nitrate leaching using subsurface drip irrigation (SDI), (2) conserve water by limiting irrigation during low-sensitivity growth stages, (3) improve crop water use estimates by developing local crop coefficients, and (4) determine the environmental impact of land application of cattle manure by measuring leaching rate of nitrate and antibiotics.

APPROACH: To accomplish objective 1, 3 irrigation and 3 nitrogen management strategies will be compared using a subsurface drip irrigation (SDI) system. Nitrogen treatments will include both preplant applications and in-season fertigations based on weekly chlorophyll meter readings. Irrigation treatments will be based on %ET. Also, a surface-irrigated treatment will be included in the design, in order to quantify the environmental impact of changing from surface irrigation to SDI, in terms of reduced nitrogen leaching and potential water savings. Objective 2 will be accomplished using a multiple cropping system research facility in which each plot is irrigated independently using a solid set sprinkler system. The cropping system includes several crop rotations, including corn, soybean, and wheat. Crops will be irrigated following 4 different strategies, trying to save water by creating stress during stages when it is not expected to significantly reduce yields. The approach for objective 3 is to measure crop ET directly using the Eddy Covariance and Bowen ratio methods, for the main irrigated crops grown in the area (mainly corn and soybean). From these measurements, local crop coefficients will be derived. These crop coefficients will be used to improve procedures used to estimate crop ET for these crops. For objective 4, the leaching of nitrate and antibiotics resulting from the application of cattle manure as fertilizer for fully-irrigated corn will be quantified. Leaching will be measured by taking profile soil samples and by collecting leachate from percolation lysimeters. A set of 12 percolation lysimeters will be used for this experiment, which will include 3 treatment and 4 replications. Treatments include the application of two rates of manure and one chemical fertilizer treatment as the control. Time domain reflectometry (TDR) probes will also be installed at different depths to follow nitrate leaching.

NON-TECHNICAL SUMMARY: Nebraska has water quantity and quality challenges. Kansas is demanding more water from the Republican River. To meet regulations, Nebraska will have to allocate water for wildlife in the Platte River. Also, in some areas, a water allocation system has been adopted in response to declining aquifer levels and high levels of agricultural pollutants in groundwater. High cost of energy and low commodity prices are also incentives to produce with less water. The aim of this project is to find ways to produce with less water and protect groundwater from agricultural pollutants.

PROJECT CONTACT:

Name: Payero, J. O.
Phone: 308-532-3611
Fax: 308-532-3823
Email: jpayero2@unl.edu

Item No. 22 of 27

ACCESSION NO: 0170508 SUBFILE: CRIS
PROJ NO: NEB-44-051 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 01 DEC 1995 TERM: 30 NOV 2001 FY: 2002

INVESTIGATOR: Yonts, C. D.; Wilson, R. G.

PERFORMING INSTITUTION:
PANHANDLE RES & EXTENSION CNTR
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

AGRICHEMICAL CONTROL IN IRRIGATION RUNOFF WATER FROM SURFACE IRRIGATED FIELDS

OBJECTIVES: The goal of this project is to develop a method for reducing the amount of chemical present in agricultural runoff from furrow irrigated fields. Objectives are to: Determine the presence of agricultural chemicals in irrigation runoff waters in the North Platte Valley. Evaluate the potential of using vegetative filter strips for reducing the pesticide and nutrients in furrow irrigation runoff water. Compare different types of vegetative material in reducing chemical loads.

APPROACH: Irrigation runoff water will be tested for common chemicals used on irrigated fields in the Nebraska Panhandle. Water will be sampled before it enters the field and as it leaves the field. Inflow and outflow will be measured. Chemicals that offer the highest potential for moving off of the field will be used with vegetative filters. To evaluate vegetative filters for furrow irrigation, small plots representing vegetative filter strips will be planted using legumes or perennial grasses. A chemical solution will be tank mixed and applied to the plots at a rate of approximately 4 gal/min per 30 inch furrow. Samples will be collected after the vegetative filter strip at 15 minute intervals for up to 60 minutes. Total inflow and outflow from each plot will be monitored. The samples will be analyzed to determine the chemicals in solution using the enzyme immunoassay developed by Ohmicron and will be analyzed in our laboratory at the Panhandle Research and Extension Center.

NON-TECHNICAL SUMMARY: Vegetative filter strips are being considered as a method to control agrichemical runoff from furrow irrigated fields. Current research has focused on the chemicals in runoff water that occur due to natural precipitation. The objectives of this project are to determine the level of agricultural chemicals in surface irrigation runoff water and evaluate the effectiveness of vegetative filter strips to reduce agricultural chemicals in surface irrigation runoff waters.

PROGRESS: 1995/12 TO 2001/11
Narrow(1.5-4.6 m) vegetative filter strip plots were established to test the effectiveness of reducing the amount of agricultural chemical in furrow irrigation runoff water. Vegetative strips were established using smooth bromegrass and crested wheatgrass and compared with bare soil. Furrow runoff volume was 0.25 l/s and was similar to runoff volumes measured in the field. Chemicals were mixed in a solution to obtain a minimum concentration of 10 ppm for nitrate, 3 ppb for cyanazine, 5 ppb for alachlor, 3 ppb for chlorpyrifos, 50 ppb for 2, 4-D and 5 ppb for atrazine. The vegetative strips of grass proved to be ineffective in reducing the amount of agricultural chemicals leaving the field in the runoff water. Surge irrigation compared to conventional irrigation provided significant reductions in furrow advance time and tended to reduce sediment loss for fields with greater slope. This was partially due to the reduction in total runoff volume that occurs with surge. When Polyacrylamide (PAM) was added to irrigation water, soil particles were bound together and sediment loads measured leaving the field were significantly reduced for both surge and conventional irrigation. Furrow advance time increased when PAM was used in the water. This would demonstrate the importance of increasing furrow stream size when PAM is used in order to maintain the desired advance time down the field and the desired irrigation uniformity. Because of PAM's ability to control sediment loss from the field, increasing stream size should improve furrow advance time without increasing sediment loss from a field.

IMPACT: 1995/12 TO 2001/11
The establishment of narrow vegetative filter strips at the bottom end of furrow irrigated fields were not effective in reducing the loss of agricultural chemicals that may be present in runoff water. Mixing Polyacrylamide (PAM) in the irrigation water is an effective method of reducing the detachment and movement of soil within and off over 1.3 million hectares of furrow irrigated land in Nebraska. Reducing sediment loss through the use of PAM offers the ability to keep applied agricultural chemicals on the field and out of return flows to streams and rivers.

PUBLICATIONS: 1995/12 TO 2001/11
No publications reported this period

PROJECT CONTACT:

Name: Yonts, C. D.
Phone: 308.632.1246
Fax: 308.632.1365
Email: cyonts1@unl.edu

Item No. 23 of 27

ACCESSION NO: 0190127 SUBFILE: CRIS
PROJ NO: NEB-44-059 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 JUN 2000 TERM: 31 MAY 2005 FY: 2002

INVESTIGATOR: Blumenthal, J. M.

PERFORMING INSTITUTION:
PANHANDLE RES & EXTENSION CNTR
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

DYNAMIC NITROGEN MANAGEMENT FOR CROPS GROWN IN THE HIGH PLAINS OF NEBRASKA

OBJECTIVES: 1) Compare site-specific (based on soil test parameters) and uniform N fertilizer management on irrigated sugarbeet and wheat to increase profitability and N use efficiency and to identify the factors governing the relative performance of these two N management strategies. 2) Compare usefulness of Minolta SPAD 502 chlorophyll meter and Horiba Cardy meter, two simple, inexpensive tools for infield assessment of plant N status, to predict in-season N demand of irrigated sugarbeet and wheat. 3) Develop split application strategies for N application in irrigated sugarbeet and wheat to increase profitability and N use efficiency by matching plant N demand with N supply from the soil and fertilizers. 4) Quantify N cycling and fertilizer N response irrigated dry beans and dryland corn, crops important to western Nebraska, to develop and refine N management to increase profitability and N use efficiency. Specifically: a) quantify dry bean yield, N economy, and populations of Rhizobium soil bacteria on the scale of a production field. b) develop a response surface of plant population densities and nitrogen fertilization for dryland corn grown in the semiarid central High Plains.

APPROACH: 1) Studies will be conducted annually in three sugarbeet or wheat production fields, respectively. This research will be done in collaboration with growers, who will raise the crops according to best management practice. Detailed soil sampling (100 to 150 ft grid) will describe organic matter, soil pH, soil phosphorous, and soil nitrate. Based on semivariogram analysis, kriged maps of these soil properties will be made for each site. Based on this information and on the University of Nebraska sugarbeet recommendations, a N application map will be created for the whole field. Prior to planting, the following N rates will be applied in field length strips (35 ft wide) parallel with the furrows: 0 N, 1/3 recommended rate [RR] (recommended rate being the average N rate for the field as determined above), 2/3 RR, RR, 4/3 RR, and variable rate. Other fertilizers will be applied preplant at a uniform rate according to University of Nebraska recommendations. The fertilizer will be incorporated after application. The experimental design is a randomized complete block with 4 to 5 replicate blocks depending on field size and geometry. 2) Starting at the 8 to 10 leaf stage (sugarbeets) or in mid April (wheat), leaf chlorophyll readings using a Minolta SPAD 502 chlorophyll meter and petiole / stem nitrate determinations using a Horiba Cardy meter will be collected at a biweekly interval. Specific leaf area and leaf N will be determined and specific leaf N will be calculated. Relationships between yield components and chlorophyll meter readings and petiole / stem nitrate readings will allow determination of the potential of the Minolta SPAD 502 chlorophyll meter and the Horiba Cardy meter for managing N in these crops. 3) A project will be conducted in a dry bean production field under center pivot irrigation. Detailed soil sampling will describe soil properties. After bean planting, the fertilizer treatments (0, 15, 30, 45, 60, 75 lb. N/acre) will be established in strips across the field and replicated four times. The experimental design is a randomized complete block with 4 replicate blocks. Fertilizer uptake and N fixation will be measured using N15 methodology. Adding N15 to fertilizer is a way to determine what proportion of N found in dry beans was derived from the fertilizer and what proportion was derived from fixation. Soil Rhizobium bacteria will be isolated at 50 locations in the field and characterized using genetic techniques (DNA fingerprinting). 4) A two-year study will be conducted annually in dryland corn production fields at four locations in western Nebraska . This research will be done in collaboration with dryland corn growers, who will raise the crop according to best management practice. At each location an identical experiment will be established: One corn cultivar will be no-till seeded into winter wheat stubble at five different populations (8,000, 12,000, 16,000, 20,000, and 24,000 plants/acre). Each of these corn populations will receive five different N fertilizer rates (0, 30, 60, 90, or 120 pounds N/acre). The experimental design is a randomized complete block with four replicate blocks.

NON-TECHNICAL SUMMARY: Applications of nitrogen fertilizers have increased crop yields tremendously. Simultaneously, nitrogen fertilizers have been implicated in pollution of surface and ground water. The goal of this work is to refine nitrogen management to increase crop yield and quality, while protecting the water resource.

PROGRESS: 2001/10 TO 2002/09
The importance of proper nitrogen nutrition in sugarbeet production is well-known. Lack of nitrogen will result in significant reduction in root yields, while excess nitrogen will promote significant decreases in sucrose content. The objective of this study was to evaluate in field-scale experiments the effect of fertilizer nitrogen on yield components of sugarbeets. In 2000 and 2001, two experiments were established each year in western Nebraska. Five rates (0, 30, 60, 90, and 120 kg N/ ha) of UAN were applied sidedress in early June in field length strips. Soil parameters, stand establishment, root yield and quality were measured. Due to harsh weather conditions in 2000 (late planting of the crop on May 10 and hailstorm on July 11) yields were with an average of 46.3 Mg/ha rather low and on a whole-field scale nitrogen fertilization did not increase the amount of sucrose harvested. In 2001 yields averaged 61.0 Mg/ha and nitrogen fertilization increased beet tonnage by 5.6 Mg/ha. Effects and interactions of soil nitrate at planting, fertilizer treatments, and stand density on yield components of sugarbeet varied within and among fields. Knowledge of rhizobial symbionts associated with native prairie legumes in the USA is limited. In this study, sixty-six strains of rhizobia were isolated from the root nodules of Amorpha canescens, A. nana, A. fruticosa, and Astragalus canadensis. We used phenotypic and genotypic approaches to examine the diversity among these rhizobia and to determine their relationship with known rhizobia. The isolates varied in phenotypic and genotypic characteristics and exhibited significant diversity. The majority of strains of A. canescens were related to Mesorhizobium huakuii and Mesorhizobium loti, exhibited intermediate to slow growth rates, and produced acid on yeast mannitol agar. Few isolates showed similarity to species of Rhizobium and Bradyrhizobium, although isolates from A. nana were closely related to Bradyrhizobium japonicum and 77% of isolates from A. fruticosa related to Bradyrhizobium elkanii based on DNA-fingeprinting data. Strains of A. canadensis related to M. loti. They included both fast and slow growers and were acid producers also. Plant infection tests revealed that cross-inoculation between strains of the three species of Amorpha and A. canadensis occurs. All strains evaluated were able to nodulate Phaseolus vulgaris and many of the isolates nodulated Glycine max.

IMPACT: 2001/10 TO 2002/09
This project developed new information on impacts of site specific nitrogen nitrogen management on sugarbeet production in the Great Plains. More than 200,000 acres of sugarbeet are produced in this area and application of the findings of this research could have an economic effect of $ 35 / acre. New information about nodulation characteristics of prairie legumes was developed that can aid in the restoration of the more than 50 million acres of rangelands.

PUBLICATIONS: 2001/10 TO 2002/09
1. Eghball, B., J.E. Gilley, D.D. Baltensperger, and J.M. Blumenthal. 2002. Phosphorus and Nitrogen in Runoff Following Long-term and Recent Manure and Fertilizer application. Trans. ASAE 45:687-694.
2. McCallister, D.L., M.A. Bahadir, and J.M. Blumenthal. 2002. Phosphorus Partitioning and Phosphatase Activity in Semi-arid Region Soils Under Increasing Crop Growth Intensity. Soil Science 168:(in press).
3. Blumenthal, J.M. 2002. Variation of Nitrogen Fertilizer Response in Sugarbeet Production Fields. Agronomy Abstracts (CD-ROM).
4. Lyon, D.J., J.M. Blumenthal,R.H. Harveson, D.D. Baltensperger, and P.A. Burgener. 2002. Winter Wheat Response to Elimination of Summer Fallow in Semiarid Western Nebraska. Agronomy Abstracts (CD-ROM).

PROJECT CONTACT:

Name: Blumenthal, J. M.
Phone: 308-632-1372
Fax: 308-632-1365
Email: jblumenthal1@unl.edu

Item No. 24 of 27

ACCESSION NO: 0164811 SUBFILE: CRIS
PROJ NO: NEB-48-023 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 01 JUN 1994 TERM: 31 MAY 2000 FY: 2000

INVESTIGATOR: Selley, R.

PERFORMING INSTITUTION:
SOUTH CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

FORMULATION OF NITROGEN FERTILIZATION RECOMMENDATIONS TO MAXIMIZE ECONOMIC AND ENVIRONMENTAL GOALS

OBJECTIVES: 1. Provide guidance on how to formulate statewide recommendations considering producer and social objectives. 2. Study producer response to recommendations, focusing upon behavioral patterns and producer characteristics, and their influence on producer acceptance. 3. Estimate the cost of collection of site specific information, the cost of recommendation errors due to lack of site specific information, and the cost of adjusting application rates within and between sites. 4. Rank additional information that could potentially lead to refinement in nitrogen fertilization recommendations, e.g. should we be asking for past N levels, whether the land is dryland or irrigated, the type of irrigation.

APPROACH: The objectives of this project will be pursued using data from central Nebraska.It is intended to develop procedures that could be applied to a larger study area such as the State of Nebraska. Producer response to N fertilization recommendations will be studied by identifying patterns of behavior using reports of soil tests and fertilizer application rate submitted to the Central Platte NRD. Obj. 2 will be further pursued through group focus interviews and/or a survey questionnaire. Obj. 3 will be pursued with interviews of producers and dealers to determine sampling and applications costs and to develop budgets to summarize those costs. Obj. 4 will involve using EPIC, a crop simulation model for estimating N leaching and yields.

NON-TECHNICAL SUMMARY: Nitrogen fertilization of crops is profit motivated but has the risk of contamination of ground and surface water. This project seeks to identify procedures for making nitrogen fertilization recommendations that will result in application rates that balance profit and environmental risk.

PROGRESS: 1994/06 TO 2000/05
It was demonstrated that practices designed to protect and improve the groundwater should be evaluated in terms of their net impact upon the ground water. Under irrigation this means determining, for example, nitrate leaching less the nitrate removed from the aquifer through pumping. When recognizing the influence of the nitrate level in the ground water it follows that best management practices may differ depending on the level of nitrate in the ground water. It was also shown that simulating a single point in a gravity irrigated field to evaluate net nitrate leaching can lead to erroneous results. Contrary to expectations, simulation results indicate pumping in excess of crop needs using a gravity irrigation system may be most attractive economically and environmentally when the nitrate levels in the ground water are high. Irrigating for crop needs with a center pivot system is attractive when ground water nitrate levels are low. Also contrary to expectations, a corn-soybean rotation is not always superior environmentally to continuous corn evaluated based on net nitate leaching. It was found in the Central Platte river valley producers typically apply more nitrogen than is recommended when the recommendation is relatively low. However, environmentally concerned, well educated, well informed and younger producers were more likely to apply nitrogen near recommended levels.

IMPACT: 1994/06 TO 2000/05
The major impact of this research has been upon the methods used in evaluating production practices. As these procedures are implemented, best management practices will have to be formulated for the situation, both the environment, the level of understanding on the part of producers and their willingness to bear risk.

PUBLICATIONS: 1994/06 TO 2000/05
1. Zara,P, R.Selley,et.al. 1994. Simulating N Leaching in Furrow Irrigated Corn, Irrig Science. Vol 15, No 4, Dec.
2. Supalla,R, R.Selley,et.al. 1995. Analysis of Factors Affecting the Adoption of Nitrogen Management Practices fot Improving Water Quality. J. of Soil and Water Conservation. Jan-Feb.
3. Selley. R. and P. Wilson. 1997. Risk Research and Public Outreach: A Tale of Two Cultures?. J of Agricultural and Resource Economics, 22(2):222-232.
4. J. Cahoon, R.Selley, et. al. 1999. Corn yield Response to Tillage with Furrow Irrigation. J of Production Ag, Vol 12, No2, Apr-Jun.

PROJECT CONTACT:

Name: Selley, R. A.
Phone: 402-762-3535
Fax: 402-762-4422
Email: RSelley1@unl.edu

Item No. 25 of 27

ACCESSION NO: 0178531 SUBFILE: CRIS
PROJ NO: NEB-48-025 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: TERMINATED
START: 15 MAY 1998 TERM: 30 SEP 2001 FY: 2001

INVESTIGATOR: Benham, B. L.

PERFORMING INSTITUTION:
SOUTH CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

SUBSURFACE DRIP IRRIGATION: INTEGRATED WATER & NITR. BMPS FOR CORN & ASSESSING IRRIGATION UNIFORMITY

OBJECTIVES: Develop subsurface drip irrigation (SDI) integrated water & nitrogen best management practices (BMPs) for corn grown on the Northern Great Plains. Develop methods that can be used to measure SDI uniformity in situ.

APPROACH: Irrigation will be applied at two frequencies weekly & multiple times per day (high frequency). Nitrogen applications will not be fixed at some predetermined level, but will be reactively scheduled based upon in-field plant observations. Nitrogen applications will be applied at rates commensurate with corn-specific nitrogen (N) uptake-functions recently developed in Nebraska. The hypothesis: high frequency SDI coupled with reactively scheduled N fertigation will increase corn grain yields while reducing or eliminating percolation. Treatments will include irrigation frequency, irrigation amount, and total N applied. Noninvasive devices will be tested to determine if they can be used to measure SDI uniformity in situ. Tests will be conducted over a range of 6 irrigation application depths & in 3 general soil textural classes, fine sand, loam, & clay loam. Analytical unsaturated flow models will be used to simulate SDI infiltration patterns for the water application depths. Simulated infiltration patterns will be compared to the noninvasive device results. Effectiveness of the tested devices will be based upon model predictions and measured infiltration patterns.

NON-TECHNICAL SUMMARY: The need to increase corn grain yields and limit nitrate leaching using alternative irrigation methods and technology. The investigation hypothesis states: high frequency subsurface drip irrigation coupled with reactively scheduled N fertigation will increase grain yields while reducing or eliminating nitrate percolation below the root zone.

PROGRESS: 1998/05 TO 2001/09
The principal investigator is no longer employed by the University. Last year's report was the termination report.

PUBLICATIONS: 1998/05 TO 2001/09
No publications reported this period

PROJECT CONTACT:

Name: Benham, B. L.
Phone: 402.762.3535
Fax: 402.762.4422
Email: BBENHAM1@UNL.EDU

Item No. 26 of 27

ACCESSION NO: 0185058 SUBFILE: CRIS
PROJ NO: NEB-48-026 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 FEB 2000 TERM: 31 JAN 2005 FY: 2002

INVESTIGATOR: Ferguson, R. B.

PERFORMING INSTITUTION:
SOUTH CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

SITE-SPECIFIC NUTRIENT MANAGEMENT STRATEGIES FOR IRRIGATED AND NON-IRRIGATED MAIZE

OBJECTIVES: 1. Investigate site-specific N management strategies for irrigated and non-irrigated maize production. a) Evaluate soil/climate/production system parameters for feasibility of improved N use efficiency with site-specific N management. b) Investigate the potential for site-specific use of nitrification inhibitors. c) Investigate cost-effective approaches to site-specific N management for maize. 2. Investigate the potential for site-specific management of other inputs to maize - initially hybrid, but potentially also including seed density, phosphorus and lime - for improved efficiency, improved yield, or both.

APPROACH: Field trials will be implemented using randomized, replicated field-length treatment strips, primarily on producers fields. Treatments will depend on the specific study, but will include N rates, nitrification inhibitor rates and the combination thereof, and maize hybrids. Environments, or management zones, will be defined from combinations of existing soil series, bare soil aerial photographs, digital elevation models, soil conductivity, remotely sensed aerial images of the growing crop, crop yield maps and directed or grid-based soil samples. Models for differential response of the input variable (N, hybrid, etc) will be derived for management zones developed for each site. The stability and predictability of management zones over years will be evaluated.

NON-TECHNICAL SUMMARY: Crop response to inputs such as nitrogen and hybrid can vary spatially and temporally. Technology now exists to manage inputs spatially, but knowledge is lacking in how to effectively use precision agriculture tools to increase the efficiency of cropping inputs such as nitrogen fertilizer. This project seeks to measure the extent of variability of maize yield response as influenced by inputs such as nitrogen, nitrapyrin and hybrid. The goal is to develop strategies to allow variable input according to management zones which are stable and predictable.

PROGRESS: 2001/10 TO 2002/09
A range of field studies were initiated in 2002 to investigate site-specific nutrient response in irrigated maize. One project, supported through USDA/NASA - IFAFS funding, is examining processes to integrate various layers of information, primarily related to soil properties, into meaningful management tools for irrigated maize. Four sites were established in 2002, three located on producers fields. Each site is center-pivot irrigated. Base information for each site includes soil series, DEM, DOQ, apparent soil EC, and yield maps over at least 4 years. Approximately 250 locations within each field were sampled with a combination of triangular grid, transect, and random points. Laboratory analysis of a range of soil properties from this sampling has been completed. Treatment designs for 2003 will be based on analysis of soil properties, IKONOS satellite imagery, and yield maps from 2002 and prior years. This study will continue through the 2003, 2004 and 2005 growing seasons. A second project was established on 12 sites in 2002, 3 of which are coincident with the 3 sites listed above. This project is designed to re-evaluate basic nutrient recommendations for irrigated maize as influenced by soils and climate across Nebraska. The 12 sites were selected to be representative of major agro-ecological zones within the state. Small plots with ranges of N, P, K rates were established at each site. Sulfur was an additional variable at some locations. One goal of the project, to be continued in 2003 and 2004, is to determine if soil/climate-specific N recommendations can be established for irrigated maize that may be appropriate for variable rate management. (Prior research in Nebraska has shown that variable rate application of current N recommendation procedures provides no advantage to uniform N application.) A range of soils and crop data has been collected from these sites in 2002.

IMPACT: 2001/10 TO 2002/09
Since both of these projects were initiated in 2002 and are in progress, no significant findings are yet available. Expected outcomes from these projects include new tools for producers to variably manage inputs within fields of irrigated maize. The use of these tools should result in more efficient utilization of inputs and/or reduced environmental impact of irrigated maize production.

PUBLICATIONS: 2001/10 TO 2002/09
1. Eigenberg, R.A., J.W. Doran, J.A. Nienaber, R.B. Ferguson, and B.L. Woodbury. 2002. Electrical conductivity monitoring of soil condition and available N with animal manure and a cover crop. Agric. Ecosystems & Environment 88:183-193.
2. Pedersen, S.M., R.B. Ferguson, and R.M. Lark. 2001. A multinational survey of precision farming early adopters. Farm Mgmt. 11:147-162
3. Pedersen, S.M., R.B. Ferguson, R.M. Lark. 2000. A Comparison of Producer Adoption of Precision Agricultural Practices in Denmark, the United Kingdom, and the United States. University of Nebraska. Research Bulletin 343.

PROJECT CONTACT:

Name: Ferguson, R. B.
Phone: 402-762-4431
Fax: 402-762-4422
Email: RFerguson1@unl.edu

Item No. 27 of 27

ACCESSION NO: 0192023 SUBFILE: CRIS
PROJ NO: NEB-48-029 AGENCY: CSREES NEB
PROJ TYPE: HATCH PROJ STATUS: NEW
START: 01 FEB 2002 TERM: 31 JAN 2007 FY: 2002

INVESTIGATOR: Elmore, R. W.

PERFORMING INSTITUTION:
SOUTH CENTRAL RES & EXT CENTER
UNIVERSITY OF NEBRASKA
LINCOLN, NEBRASKA 68583

RESOURCE-EFFICIENT CROPPING SYSTEMS RESEARCH FOR SOUTH CENTRAL NEBRASKA'S IRRIGATED AGRO-ECOLOGICAL ZONE.

OBJECTIVES: This project's overarching objective is to make our cropping systems more resource-efficient while maintaining or improving productivity and profitability. A. Planting patterns and genotypes. 1. Corn Studies. a. Narrow row: Precipitation limits potential ET of corn in South Central Nebraska and this limits yields. These studies are designed to determine if narrow rows improve WUE and corn grain yields relative to conventional wide-row corn production systems and if these responses are affected by water regime. b. Plant spacing and developmental uniformity: The relationship between average yields and the level of neighborhood competition has not been specifically demonstrated in irrigated, high-input maize production systems. Our overall goal is to relate the effects of plant spatial and developmental uniformity to maize yield and to the occurrence of green-snap in irrigated systems. 2. Soybean Studies: Seed size studies: To determine production systems that optimize yield and seed size of large- and small- seeded soybean cultivars. B. Growth and development. 1. Corn Studies. Greensnap - Mid-Season stalk breakage: The objective of this series of experiments is to reduce the impact of high-velocity mid-season winds on corn profitability. Components of this project will address the following questions: i) Why are some hybrids more susceptible than others, and ii) Why are some plants broken and some are not? C. Transgenic crops - Biotechnology derived crops. 1. Corn Studies. Glyphosate resistant hybrid- isoline comparisons: To determine the effect of the NK603 glyphosate resistant gene event on GR corn hybrids. 2. Soybean Studies: Effects of Glyphosate on nodulation and yield of Glyphosate Resistant soybean cultivars with and without irrigation: The objective of this work is to determine the effect of glyphosate on GR soybean plant and nodule development as well as yield with irrigated and rain-dependent field conditions.

APPROACH: This project's overarching objective is to make our cropping systems more resource-efficient while maintaining or improving productivity and profitability. A. Planting patterns and genotypes. 1. Corn Studies. a. Narrow row: Precipitation limits potential ET of corn in South Central Nebraska and this limits yields. These studies are designed to determine if narrow rows improve WUE and corn grain yields relative to conventional wide-row corn production systems and if these responses are affected by water regime. b. Plant spacing and developmental uniformity: The relationship between average yields and the level of neighborhood competition has not been specifically demonstrated in irrigated, high-input maize production systems. Our overall goal is to relate the effects of plant spatial and developmental uniformity to maize yield and to the occurrence of green-snap in irrigated systems. 2. Soybean Studies. Seed size studies: To determine production systems that optimize yield and seed size of large- and small- seeded soybean cultivars. B. Growth and development. 1. Corn Studies. Greensnap - Mid-Season stalk breakage: The objective of this series of experiments is to reduce the impact of high-velocity mid-season winds on corn profitability. Components of this project will address the following questions: i) Why are some hybrids more susceptible than others, and ii) Why are some plants broken and some are not? C. Transgenic crops - Biotechnology derived crops 1. Corn Studies. Glyphosate resistant hybrid- isoline comparisons: To determine the effect of the old glyphosate resistant gene event on GR corn hybrids. 2. Soybean Studies: Effects of Glyphosate on nodulation and yield of Glyphosate Resistant soybean cultivars with and without irrigation: The objective of this work is to determine the effect of glyphosate on GR soybean plant and nodule development as well as yield with irrigated and rain-dependent field conditions.

NON-TECHNICAL SUMMARY: The projects described here are designed to seek answers to current producer questions and problems involving crop genotypes and cultural practices in this agro-ecological zone. The questions and problems are in three areas: planting patterns and genotypes; crop growth and development; and transgenic or biotechnology-derived crops. The projects described are designed to seek answers to producer questions involving crop genotypes and cultural practices in this agroecological zone.

PROGRESS: 2001/10 TO 2002/09
1. A narrow row corn study in different water regimes was planted for the third year in 2001. The data are waiting for processing. 2. Both small plot and on-farm trials were conducted in 2001 and 2002 to study the effect of plant spacing uniformity on corn yield. Although planter speed increases in the on-farm studies also increased plant spacing variability, grain yield was not affected in 2001. The 2002 data are not yet processed. 3. Attempts to understand mid-season greensnap in corn continued in 2002 with studies focusing on a 24 hour simulated break study and the effects of early-season wind on leaf orientation. A grant proposal is being prepared for submission on this portion of the project. 4. Four glyphosate-resistant soybean cultivars were compared for the second year with and without inoculation in rain-dependent and irrigated environments at two locations. The objective is to determine the effect of glyphosate on inoculation, plant growth, and yield. Data are being processed.

IMPACT: 2001/10 TO 2002/09
Our work with farmers looking at the effects of planter speed on plant spacing variability has encouraged many producers to calibrate their planters before the growing season starts.

PUBLICATIONS: 2001/10 TO 2002/09
No publications reported this period

PROJECT CONTACT:

Name: Elmore, R. W.
Phone: 402-762-4433
Fax: 402-762-4422
Email: relmore1@unl.edu