ISU research complicates cover crops


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Cover crops hold onto soil and carbon during the off-season (via Creative Commons).

Julia Poska| November 13, 2019

Though cover cropping has proven advantageous for soil and water conservation in Iowa, the practice’s benefits to atmospheric quality may be negligible, new research from Iowa State University found.

When farm fields are left bare during the winter and spring, wind and water transport soil and nutrients off the land and into streams and rivers, degrading both the field and water quality. Exposed soil typically releases carbon into the atmosphere at increased rates compared to planted areas, contributing significantly to climate change.

Cover cropping involves planting alternative crops like rye or clover to cover and nourish the land throughout the off-season. The conservation practice holds soil in place, pulls atmospheric carbon into plant material and adds carbon back into soil upon decomposition. Sequestering carbon in plants and soil is key to combatting climate change.

That carbon may not remain in the soil for long, however. The new study, published in Global Change Biology Bioenergy,  found that the added soil carbon stimulates microbes in the soil that emit carbon dioxide back into the atmosphere as they digest the organic matter.

The research — conducted by ISU assistant professor of ecology, evolution and organismal biology Steven Hall and grad student Chenglong Ye —  highlights the need for a variety of solutions for the planet’s numerous natural resource problems. While cover crops are a proven protectors against water pollution, we will need to implement other strategies to make farming carbon neutral, too.

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