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Advancing Innovative Cover Crop Research, One Question at a Time

December 4, 2012


The U.S. Department of Agriculture’s Natural Resource Conservation Service recently launched a soil health initiative entitled, “Unlock the Secrets in the Soil.” The initiative aims to help farmers enhance soil health by raising awareness and sharing methods and success stories. 

This is the second post in a five-post series on sustainable soil management, research, and demonstration, with a specific focus on USDA’s Sustainable Agriculture Research and Education (SARE) program.  SARE has over two decades of experience in helping farmers and agencies like Extension and NRCS focus on soil quality.


Guest Post by Andy Zieminski, SARE Communications Associate

Cover crop species are selected based on a range of benefits they provide. For example, Tillage Radish, developed by Pennsylvania farmer and SARE grantee Steve Groff, recycles nutrients and penetrates hardpan like a drill. Photo Credit: Mandy Rodrigues, SARE Outreach

With every season, the wealth of scientific knowledge is growing around cover crops’ numerous benefits to soil health, plant productivity and resource conservation.  Yet, a barrier to more widespread adoption is reflected in the perfectly reasonable question posed by many a cautious farmer: “Yes, but will it work on my farm?”

Answering on-the-ground questions is what motivated Practical Farmers of Iowa to use a 2009, multi-year grant from USDA’s Sustainable Agriculture Research and Education (SARE) program to conduct cover crop research trials on farms throughout Iowa and Minnesota.  This is a case of farmers discovering the benefits of cover crops, and sharing their knowledge with each other: To date, 25 participating farmers have established their own trials on a range of topics, including aerial seeding, weed suppression, seeding rates, the use of tillage radish to cycle nutrients and break compaction, and, ultimately, the effect of cover crops on cash-crop yield.

SARE has long been at the forefront of supporting the innovative producers, educators and researchers who are making cover crops one of the most indispensable cost-saving tools in the soil-health toolbox.  Since SARE was established in 1988, the program has funded literally hundreds of cover crop projects throughout the United States and island protectorates.

SARE funded some of the earliest modern research on cover crop mixtures, or “cocktails”—blends of species that combine the unique ability of each species to fix nitrogen, capture excess soil nutrients, suppress weeds or break soil compaction.  For example, a University of Maryland project (1989 SARE grant) showed that a mixture of cereal rye and hairy vetch in a no-till corn system can scavenge up to 80 pounds of nitrogen (N) per acre, and can fix another 100 pounds of N.

More recently, Oregon State University Extension specialists developed an online calculator (2009 SARE grant) to help farmers predict how much N various cover crop cocktails will add to the soil.  More than 600 people have registered to use it, representing 52,000 acres.

Along with choosing the right cover crop varieties, management challenges can abound, including when to plant cover crops and how to terminate them.  An ongoing North Carolina State University project (2010 SARE grant) found that the termination method for leguminous cover crops affects how much N is made available to the subsequent cash crop.  Roll-killed hairy vetch provided more available N six weeks after termination than other combinations of legumes and kill methods, including herbicides, flail mowing and tilling.

Ohio farmer Jeff Rasawehr, a 2009 SARE grantee, illustrates cover crops’ role in protecting water quality. The jar on the right holds runoff from a cover-cropped field; on the left is runoff from a non-cover-cropped field. Photo credit: Sean McGovern, SARE Outreach

A University of Massachusetts study (2006 SARE grant) discovered an advantage in early maturing corn hybrids: They had yields similar to standard hybrids, and, because of an earlier harvest date, increased the chance of seeding a cover crop near the optimal date for maximum growth.  One of the farmers collaborating with Practical Farmers of Iowa tested aerial seeding into soybeans as a strategy for establishing early cover crops.  Plots seeded by air on Sept. 10 produced more biomass on average than drill-seeded cover crops on Oct. 6.

In light of this year’s drought, one of farmers’ most critical questions about cover crops is how they affect available soil moisture, and thus yields, for following cash crops.  Nebraska farmers Keith and Brian Berns found an answer (2007 SARE grant) they liked, using cover crops to increase corn yield by about 10% in a non-irrigated system.

One of cover crops’ most important roles is to protect soil from erosion, and water from nutrient leaching.  An Ohio State University graduate student (2008 SARE grant) found compelling evidence of this: During simulated rainstorms, cover crops and no-till in a corn-soybean rotation nearly eliminated runoff loss of soluble N and phosphorous.

The list could go on and on. SARE grants have been used to demonstrate cover crops’ ability to eliminate winter weeds; to develop sunn hemp as a viable cover crop in Hawaii, Puerto Rico and other subtropical regions; to explore cover crops’ vital role in promoting healthy, disease-resistant soils; and more.  Such extensive, decades-long support of cover crop research is essential to being able to declare with confidence, “Yes, cover crops will work on your farm.”

For more information, visit www.SARE.org/covercrops

Read the Rest of the Series



Categories: Conservation, Energy & Environment, Research, Education & Extension


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