Cover Crops Boost Yields

By using cover crops, farmers can help boost soil nutrients, prevent soil and water erosion and increase corn, soybean and other crop yields.

Many southern growers have used cover crops for years. On the High Plains, they’re used mostly to help retain snow or rainfall, and prevent soil from blowing and damaging new plant stands.

In the Midwest, growers are finding they, too, can benefit from cover crops. Cover crops help generate better soil biology, a deeper root zone, reduce erosion and evaporation and promote better rainfall infiltration, says Ron Myers, regional director Extension programs for USDA North Central Sustainable Agriculture Programs.

In the 2012 drought year studies in Indiana, corn planted into a cover crop showed about a 10% yield increase compared to corn planted conventionally, up from 115 bushels to 127 bushels, Myers says. In similar studies, soybeans planted into a cover crop had yields increase from 42 to 47 bushels.

Cover crops are typically planted after harvest or on fallowed ground to provide fall and winter growth. They are often small grains and grasses, such as ryegrass, cereal rye, spring oats, triticale or even wheat. Many other cover crops include various legumes, radish, Hairy vetch, crimson clover, rapeseed, winter peas and others.

Myers, speaking at the recent Commodity Classic, says Midwest region surveys show that about 48% of cover crops are planted with a drill, which another 24% are broadcast in. The plants establish a good root zone, which add nutrients to the soil. The cover vegetation prevents erosion. Many cover crops may also provide winter and early spring grazing for livestock.

Cover crop termination
Mike Plummer, a conservation ag consultant, says it’s important to time cover crop termination with planting. And there’s no harm in planting corn or beans into cover crops, he says.

Termination is normally done through either winterkill or herbicide applications. Glyphosate, 2,4-D or other herbicides can be used, depending on their labels for specific row crops.

Since cover crops make for essentially a two-crop system, Plummer says growers should make sure when they must terminate them in order to comply with crop insurance rules.

Paul Jasa, University of Nebraska agricultural engineer and no-till disciple, says cover crops can benefit any cropping system. He oversees one field outside of Lincoln, NE that has been under no-till 38 years and still producing above average corn yields. He says large farmers can benefit just as much as smaller operators.

“When it comes to size, some say they’re too large to worry about it. It’s just the opposite,” Jasa says. “Diversity in crops helps the soil. Micropours buildup. The soil holds more water. Pest problems go down and beneficial insects go up.”

Jasa says cost of a single cover crop may be about $5 per acre. A cover crop mix, or “cocktail,” may cost $20-$25 per acre. “Like with corn planted after soybeans, there is residual N remaining from cover-crop residue,” he says. “Biological residue from the last year is released to benefit the next corn crop.”

Duane Beck, manager of Dakota Lakes Research Farm, Pierre, S.D., is a leading authority on cover crops. He offers these tips on using single cover crops or mixes to enhance your farm:

  • Decide what you want to do before trying to choose a cover crop, forage crop or cover-crop mixture.
  • Think of the cover crop as another component in a rotation.
  • Using a cover-crop mix adds more diversity, sees growth at different times, competes better with weeds and optimizes nutrient cycling.
  • Water used by a cover crop during the non-crop period can often be regained during the growing season because of better infiltration, reduced runoff and improved water relations. But the cover crop needs to be maintained.
  • It’s important to understand rainfall patterns and water holding characteristics of your soils to fully benefit from cover and forage crop programs.
  • Cover crop seed should be inexpensive in terms of its potential benefit. Small seeds mean less volume/acre thus requiring fewer tanks fills.
  • Small seeds grow better on the surface than larger seeds while large seeds usually emerge better through a mat of residue.
  • Using harrows to improve the stand of surface broadcast seed also improves the stand of weeds.