For many farmers in the grain and beef production regions of the U.S., the planting season ends when the last of the seed wheat or corn kernels are tucked neatly in the ground, but for a growing number of savvy farmers, it’s only the beginning.
“By not planting that cover crop after harvest, you’re passing up on a great opportunity to make more money and improve your soil health,” says Ken Miller, district technician for the Burleigh County Soil Conservation District, Bismarck, ND.
Miller should know. He and his colleagues have collected over five years of research data supporting the premise that cover crops more than pay for themselves monetarily and from an overall soil health perspective.
“When used in conjunction with late-season cattle grazing, the net return on the cover crop is over $60/acre,” Miller says. He notes that $60/acre is just the return for extra animal units grazed and doesn’t reflect in any way the monetary benefits associated with planting the following year’s crop into improved soil.
In July 7, 2007, after harvesting an 80-acre stand of field peas for grain, a cover crop cocktail – a blend of one grass (millet) and six broadleaves (cowpeas, soybeans, turnips, radish, sunflower and sweet clover) was planted.
Two other 80-acre plots were also part in the study, but neither was planted to a cover crop. One received an application of manure the other did not.
Prescription for the soil
Miller says the list of plants included in a cocktail vary depending on the condition of the soil, and the time of planting. Usually a blend of several species and plant types, each with its own unique rooting patterns and plant architecture, all contribute to a diversity that is much needed for restoring microbial and physical soil function after producing a mono crop.
Cocktails also provide good soil cover across a variety of conditions as the different cover crop types respond differently to varying soil and weather conditions. For example, millet, a warm-season grass, responds favorably to the hot summer weather patterns, emerging rapidly and forming a canopy inhibiting loss of soil moisture through evaporation. The same applies to warm-season broadleaf plants – sunflowers, cowpeas, soybeans and clover.
While the warm-season plants are creating biomass on the surface, the cool-season brassicas – turnips and radishes – are scavenging nutrients in the soil and aerating soil compactions with their tenacious taproot systems. “The beauty of this system is that there are several things going on at once,” Miller says. “What they have in common is that they all benefit the soil.”