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Some no-tillers worry their focus on soil surface conditions could mean they’re depriving crops of subsoil nutrients from fertilizers placed deep in the dirt.
But experts who study nutrient stratification — the non-uniform distribution of nutrients at various soil depths, with higher concentrations near the surface — have a simple message for no-tillers: If precautions are taken to prevent surface-level nutrients from becoming pollution-causing runoff, no-tilling enables the soil to feed crops as nature intended.
“In areas east of the Mississippi, or just west of it in areas with sufficient rainfall, we don’t see any benefit to the deep injection of nutrients, even to avoid temporary seasonal drought,” says John Grove, University of Kentucky plant scientist and director of the school’s Research and Education Center. “In our part of the world, deep injection of nutrients is just a way to sell steel.”
Paul Jasa, an ag engineer for the University of Nebraska Extension who has 40 years of no-till experience, agrees.
“Anybody who says stratification is a problem in no-till has never measured the nutrient distribution in tilled systems. There is stratification there as well,” he says.
“Back in the 1970s, when the chemical companies were teaching us how to blend in our herbicides, they said effective incorporation depth was only one-half of our tillage depth.
“And for generations we were tilling only 6-10 inches deep, so we were placing the nutrients in only the top 3-5 inches anyway. That’s right up on top, no different from no-till.”