Cover crops: Basic concept, bountiful results

by Enrico Villamaino

Cover crops are crucial, and can be well worth the cost to a farmer concerned with conservation.

As featured speaker in the Illinois Sustainable Ag Partnership’s (ISAP) risk management webinar “Myth – Cover Crops Are Just Another Input: Agronomic Benefits of a Soil Health System,” Dr. Jerry Hatfield outlined how cover crops are an asset to agricultural professionals.

Hatfield, who until his retirement served as laboratory director for the USDA’s Agricultural Research Service (USDA-ARS), explained why cover crops are important to overall soil health. “Repeated harvests followed by periods where the land is left bare can reduce the land’s functionality,” he began. “The question is, how do we restore it?” Hatfield’s answer was unambiguous. “Biological activity. That’s the number one way to restore functionality. Cover crops provide that activity.”

Cover crops: Basic concept, bountiful results

Dr. Jerry Hatfield is an affiliate professor of crop production and physiology at Iowa State University.

Hatfield explained a number of ways that off-season coverage of land is advantageous for a farmstead.

Cover crops can create a canopy which provides protection against raindrop energy, lessening the effect of erosion while shielding soil aggregates. Decreased soil losings and runoff reduces the loss of valuable nutrients and keeps pesticides and other pathogens harmful to humans from flowing into nearby bodies of water.

With their deep tap roots, cover crops assist in the mitigation of soil compaction. The various layers of field soil can be compacted during harvest, and deep tap roots can penetrate these layers. Additionally, soil water is used by the crops for transpiration, reducing the soil system’s loss of water. Furthermore, evapotranspiration results in better tillage and traffic conditions, improving the soil’s capacity to withstand heavy farm equipment, resulting in less subsurface compaction.

Nitrogen is often a product of cover crops. When a cover crop contributes to the increase in soil nitrogen, there can be a resultant decrease in the need for a farmer to apply a nitrogen fertilizer for the subsequently planted crop. This can both lower costs of production and reduce the use of purchased nitrogen fertilizer produced using fossil fuels.

At the end of its season, a cover crop’s residue can block sunlight and serve as a mulch to suppress weed growth. Some cover crop species are even allelopathic, producing chemicals that stymie weed seed germination. This means less demand for weed killers, keeping more money in a farmer’s pocket and more herbicides out of the environment.

Finally, a cover crop can provide material good for grazing livestock or making hay. Cover crops can supply food and habitat for wildlife, including beneficial insects that often serve as pollinators.

For more information visit ilsustainableag.org.

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