How do you know if your soil is good quality? Jerry Hatfield has a quick, free test to determine that.
The laboratory director of Ames, Iowa-based National Laboratory for Agriculture and the Environment, says the next time you get a 2-inch rain, go out and look at your soil surface.
“If it’s all puddled, you probably have very low aggregate stability,” he said in a recent NRCS webinar. “It makes you very susceptible to runoff and water and wind erosion.”
If that’s the case, your crop is at risk for oxygen deprivation under excessive moisture conditions. In fact, if you see yellow corn in a wet season, don’t mistake it for nitrogen (N) leaching — Hatfield says the crop is actually suffocating.
“One of the key pieces in aggregate stability is allowing oxygen to be exchanged between the soil and the atmosphere,” he says.
Soil aggregates are groups of soil particles that bind to each other more strongly than to adjacent particles. Hatfield says they’re located near the soil surface where biological activity is taking place.
Low aggregate stability is a costly problem. According to Hatfield, 55% of crop insurance claims across the Midwest are either from excessive moisture and precipitation, or drought. Hatfield clarifies that excessive moisture doesn’t include flooding — just the drowned-out spots and poor crop stands that were stunted by limited oxygen.
The good news is if you’re a long-term no-tiller, low aggregate stability shouldn’t be a problem in your fields. But if you’re in the first 5 years of no-till, then your soils are still rebuilding those aggregates.
To protect soil aggregates during the initial phase of no-till, Hatfield says to make sure you’re keeping an adequate layer of residue on the soil surface.
“If we don’t protect that soil, then that raindrop energy is beating on it, and it’s basically a very aggressive aggregate stability test,” Hatfield says, adding it only takes 0.32 of an inch of soil crust to limit water vapor and gas exchange between the soil and atmosphere.
For more information, click here to watch the recorded webinar, “The Science Supporting Changes in Soil Health.”
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