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Myths about Tillage and Nitrogen’s Effect on Residue Breakdown
by LuAnn Rolling, District Conservationist
We are looking at an earlier harvest than we have seen for years. This allows time for producers to look at post-harvest field activities, which need to be evaluated very closely, with a particular eye on soil health. Some farmers will consider tillage and nitrogen applications thinking that it may increase residue decomposition. According to Mahdi Al-Kaisi, Iowa State University Extension soil and water specialist, those activities might be counterproductive from a financial and environmental perspective.

Al-Kaisi said, “Environmentally, both tillage and fall N application are not very sustainable practices. Tillage can contribute to soil health and water quality deterioration by increasing soil erosion potential, sediment loss and water quality degradation, and fall N applications result in water quality risks.”

Al-Kaisi said tillage and fall N application can also be costly with materials, time, labor and equipment required. Since residue decomposition is controlled by biological processes that are influenced by environmental and soil conditions, Al-Kaisi’s research and other studies do not support these practices regardless of the justification or claims that propose tillage equipment can manage residue. Disturbing the soil does not constitute an improvement in soil health nor increase in residue decomposition.

The number one enemy of regenerating the life of the soil is tillage, period. Yes, cover crops, manure, green manure and even composting all benefit the life of the soil in any farming program. However, those potential gains are often offset most dramatically by the use of tillage, which destroys the house that the biology has built and lives in.

You can’t destroy the soil life’s home very many times without seriously impacting the diversity and density of the life in soils. Get away from the tillage and, for the most part, you’ve eliminated most of the erosion problems, too. Plant a cover crop and you’ve improved the erosion situation even more.

No-till as an erosion control measure is only one small part of it. Soil health is about so much more than erosion control, but you can’t have soil health if your soil is leaving the farm. You can even potentially have erosion completely under control, be 100% no-till, but still have soil with very little life in it. This is why no-till, without any other soil health measures, often isn’t very much better at regeneration of the life in the soil than a conventionally tilled field.

Soil health is not just about erosion control. It’s about a whole new perspective and respect for what our soil ought to be, and what our own personal role is in relationship to it as “faithful stewards” of that great blessing.

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