Benefits of cover crop outweigh water requirements

Cover crops have the potential to provide multiple benefits.

With the peak of winter approaching, continuing cover crop research and surveys are further supporting the idea that while cool weather cover crops require water to survive, they remain of greater benefit to harvest yields and promote better soil health.

Independent research conducted by both USDA's National Research Conservation Service (USDA-NRCS) and by Texas A&M environmental scientists at multiple test sites indicate cover crops have the potential to provide multiple benefits. Cool weather cropping systems in cotton on non-irrigated, no-till acres do require multiple years before seeing the greatest soil health benefit.

Overall, researchers say cover crops can prevent erosion, improve soil’s physical and biological properties, supply nutrients, suppress weeds, improve the availability of soil water, and break pest cycles, along with other benefits. The species of cover crop selected however, along with its management, will determine the extent of benefits and returns.

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Ongoing research indicates cool weather cover crops in cotton use more water than no-till without cover crops and increase input costs initially. Those costs, however, can be offset or justified if cover crops are used for grazing or otherwise provide farm income above normal cash crops.

Paul DeLaune, Texas A&M, says water use for cover crops also depends on whether a single cover crop or a mixed-species cover crop system is used on either dryland or irrigated acres. He reports that research indicates water use differs among cover crop species. While a multi-species mix offers greater long term benefits, they consume significantly more water than legume cover crops.

In spite of that, USDA is recommending that multi-species mix be used, a position that DeLaune supports. He says a multi-species cropping system produces the greatest biomass at his research site in Vernon, Texas.

National research

At the national level, the NRCS National Soil Health and Sustainability Team and Plant Materials Program are working together to improve understanding of cover crop mixes used to produce healthy soils. The Plant Materials Program is conducting studies at centers in California, Florida, Maryland, Missouri, North Dakota, Oregon, and Washington to evaluate the influence of seeding rates and plant diversity on soil health.

Soil scientists agree cool weather cover cropping systems for no-till fields work best to build up soil carbon, which in turn is the main factor in increasing soil infiltration. But they warn a single tillage pass can wipe out multi-year efforts to build up those carbon levels. They also warn that multiple years of using cool weather cover crops on no-till land are required to realize the greatest benefit in soil health, which in turn can clear the way for higher cash crop yields.

The issue of cover crop systems has raised concerns among many producers over whether cover crops affect crop insurance. Due to concerns that cover crops may deplete soil moisture and therefore reduce yield of the insured crop, NRCS evaluated additional research literature, plant growth and soil hydrology models, and input from national and local experts to provide the basis for developing guidelines for terminating cover crops to achieve theconservation benefit while minimizing risk of reducing yield to the following crop due to water issues. 

In addition to the revised “NRCS Cropland Cover Crop Termination Guidelines" dated September 2014 (Version 3), the USDA Risk Management Agency (RMA) is also revising some of their policy and special provisions to be compatible with the revised guidelines.

Revised guidelines

The revised guidelines include the following:

  • Grazing Consideration
    Cover Crop Grazing or Forage Harvest – Cover crops may be grazed or harvested as hay or silage, unless prohibited by RMA crop insurance policy provisions. Cover crops cannot be harvested for grain or seed.
  • Definition of Cover Crop
    Crops, including grasses, legumes, and forbs, for seasonal cover and other conservation purposes.  Cover crops are primarily used for erosion control, soil health improvement, and water quality improvement. A cover crop managed and terminated according to these guidelines is not considered a “crop” for crop insurance purposes. The cover crop may be terminated by natural causes such as frost, or intentionally terminated through chemical application, crimping, rolling, tillage, or cutting.

If a crop, or a cover crop, is planted on summer fallow acreage in a fallow year, the following planted crop will not meet the RMA Summer Fallow Practice definition until the acres lie fallow for a full crop year (where applicable). For the 2015 crop year, if a cover crop was planted during the fallow year, the acreage may be insured under the “continuous cropping practice” (if available in your county), or by written agreement if continuous cropping is not available in your county.

For the 2016 and succeeding crop years, if a cover crop is planted during the fallow year (where applicable), the acreage may be insured under the “continuous cropping practice” (if available in your county) or by written agreement (if continuous cropping is not available in your county) provided the cover crop is terminated at least 90 days prior to planting for summer- and fall-seeded crops.

Across the Southwest, most of the region falls into Zone 1, but parts of Colorado and Oklahoma fall into more than one designated zone. Texas has large areas that fall into each of the four designated zones. For complete information about RMA guidelines, summer fallow acres and how cover crops could affect crop insurance on your farm, contact your county agent of the nearest RMA office.

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