SALINA, Kan. – The weeks before the ground freezes for winter can be a good time for yard owners to come to grips with whether their soil is truly a health-promoting base for landscape and garden plants.
“One test that’s free and easy – yet, critical -- is the drainage test. To get started with that, you simply dig a 1-foot-deep hole and fill it with water. Then put boards over it so no one can step in the hole, break a leg and sue your socks off,” said Chip Miller, horticulturist with Kansas State University Research and Extension.
The second part of the test is to return the next day and fill the hole with water again. This time, however, yard owners must wait or at least check back fairly often. Their goal is to record the time required for the water to drain away, to disappear.
“Ten minutes is too fast -- an indication the soil is too light or sandy for much beyond yucca and cactus. Six hours, on the other hand, is too long for many plants because the soil is too heavy, too compacted or both,” Miller said. “The closer your soil is to either extreme, the more you need to take action.”
One solution can help fix the problems on either end of the soil drainage spectrum: Add organic matter.
“You’d almost think the stuff is smart, because it certainly knows how long to hold water and when to let it go,” Miller said. “The best organic matter is peat moss, but compost is good, too … and cheaper.
“Compost is an organic material you can buy or make at home, using everything from vegetable peels to fall leaves. Either way, it supplies nutrients, and it makes the soil a better place for roots to live.”
Adding compost to all landscape soil is rarely a practical possibility, he added. But, the more, the better.
To add organic matter, homeowners should incorporate it well throughout the soil’s tillage zone or “plow layer” – i.e., 6 to 7 seven inches deep. That’s where most roots grow, no matter if the plant is a radish or a bur oak, Miller said.
While tilling, however, yard owners must not be so zealous that they ruin the soil’s natural clumping ability. Reducing planting soil to a powder makes it difficult to work and a poor environment for roots.
“While you’re outdoors, don’t forget that fall is also a good choice for testing the soil itself,” Miller advised. “The timing allows you to make adjustments before you have to start planting next spring. Some corrections may need several months to become affective.”
Miller said he’s a nag about soil testing because homeowners simply can’t afford to take their soil’s pH for granted -- much less its nutrient content. Those kinds of characteristics can change over time. Plus, guessing wrong about which amendments to apply can lead to new and long-lasting soil problems and even plant deaths.
“You’ve probably heard that Kansas’ soils are alkaline, due to the state’s famous limestone,” Miller said. “To one degree or another, that’s true – but, only on average. In my home county of Saline, for example, soils can be acidic or alkaline. The levels can vary widely in either direction.”
The horticulturist admitted he’s not too patient about excuses -- even when people don’t have a clue about to how to test soil. Any county or district Extension office can help with soil sampling, submitting samples for testing and understanding the test results.
“The experts tend to agree that a pH of 6.5 is the best goal for gardens. That’s slightly on the acidic side of a neutral pH -- 7. It’s also within range for lots of the United States; so, many garden books reflect that fact,” Miller warned. “The books may include disclaimers, but they’re written as if everyone has acidic soils. That’s why they often recommend the addition of lime to solve everyone's soil problems.
“Well, lime does make soil ‘sweeter’ -- which is the same as saying it pushes the pH higher, making the soil more alkaline. Rather than lime, however, Kansans may need to add sulfur, which makes a too-alkaline soil more acidic. The only way they can know for sure is a soil test every three to five years.”
Soil tests also can help with on-target fertilizer selections, he said, thus avoiding a soil overload of such nutrients as phosphorus and potassium.
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