A new study from the University of Minnesota, University Southern California, Saint Louis University, the University of Hawaii, the Alliance of Biodiversity International and CIAT has found that for cover crops to succeed, farmers need to find enough land to cultivate cover crop seeds.

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There has been a rise in sustainable farming and with it there has been a rise in farming cover crops. Cover crops are typically grasses and legumes grown between the harvesting season and planting season of a land’s main cash crop. Cover crops reduce erosion, restore nutrients and carbon, create soil that can better hold moisture and control weeds and pests leading to reduced use of pesticides and chemical fertilizers ultimately improving the water quality. From 2012 to 2017, cover crop growth increased to 6.2 million hectares, or 50 percent more land.

But the study found that cover cropping may soon hit a ceiling. Planting millions of acres of cover crops would require huge extensions of land to produce cover crop seed. Currently, 1.7 percent of U.S. cropland grows cover crops. According to the researchers, between three to six percent of the 92 million acres of cropping land currently used for corn may be needed to produce crop seed. The team estimated this range based on 18 cover crops currently being used on corn farmland. The land needed to produce enough seed to scale up cover crops would cut into the land that is used to produce cash and food crops. Cover crops don’t reach seed-producing age when planted on land between harvest and planting of cash crops. Some of the cover crops with the greatest environmental benefits have poorest seed production.

Researchers found that farmers could overcome this limitation if the demand is channeled into investments in breeding programs to increase the seed yield with conventional breeding techniques or biotechnological innovations including CRISPR and Cas9 technology. Farmers can use this technology to create more dedicated breeding programs to help seed production. Another method could be expanding into temperate or tropical growing regions. This would give farmers in these areas an opportunity to produce seed for the emerging global market of crop production.

A paper on this research was published in Communications Biology.