Many farmers say they want to grow cover crops, but fear it costs too much and they won't see an economic return.
They cite high seed costs, extra labor, chemicals, extra machinery trips to plant and kill the cover crop and lack of knowledge on how to manage cover crops as factors that prevent cover crops establishment. However, farmers are experimenting and starting to overcome some of these perceived problems, says Jim Hoorman, Ohio State University water quality specialist.
"Cover-crop seed may cost as little as $5 per acre to more than $50 per acre," Hoorman says. "On the low side, oats, bin-run wheat and soybeans can be used. On the high side, legumes like cowpeas and winter peas used for homegrown nitrogen cost 80 cents to $1.20 per pound. At 40 to 50 pounds per acre, it gets a little pricey."
Hoorman says innovators are finding ways to reduce seeding rates and seed costs to $15 to $25 per acre. Innovations with drilling seed, broadcasting with fertilizer, airplane or helicopter applications, and crop inter-seeding is making cover crop establishment less risky.
As with any crop, Hoorman says understanding the life cycle, the limitations and benefits of each plant, and experience helps in growing a successful cover crop.
"The benefits of growing cover crops vary tremendously from farm to farm, depending on soil type, climate and past management," Hoorman says. "Farmers want to know whether it increases yields or lower costs.
"Unfortunately, crop yields and higher returns may be slow to improve until problems with soil management, such as drainage and soil compaction, improve. That's why the cover crop's perceived value varies from farm to farm."
Hoorman says cover crops work best on farms that work closely with Mother Nature, adding that cover crops and no-till mimic nature's cycle of keeping plants growing year-round. Cover crops feed the microbes, which feed the following crop.
He says farms that grow more plants year-round, such as livestock farms, hay, pasture or wheat fields, will respond faster than a typical corn-soybean farm that only grows a cover crop once every 5 years. Livestock farms benefit economically from using cover crops as supplemental feed and manure benefits the soil.
"Farms that plant only corn and soybeans, use conventional tillage and large amounts of commercial fertilizer and pesticides may react slower to the benefits of using cover crops because they are less reliant on microbial life for supplying nutrients to their crops," Hoorman says. "The reliance on chemical inputs comes at a price because the efficiency of commercial fertilizer decreases as the microbial life declines in the soil.
"So, while cover crops may not directly increase crop yields initially, they increase nutrient efficiency and decrease your input costs."
Hoorman says a common myth among farmers is that corn benefits directly from fertilizer. Most corn fertilizer is recycled through microbes first, so farmers actually fertilize the microbes and indirectly fertilize their corn.
As fertilizer and fuel cost increase, cover crops and no-till are economical because tillage, fuel consumption and chemical inputs become more expensive, Hoorman says.
He says cover crops improve farm economics through:
Better Drainage: If you are considering splitting your tile lines to improve soil drainage, plant a cover crop for several years, Hoorman says.
"Let's say it cost $800 per acre to split your tile lines on 40-foot spacings. Take the interest on that money — $800 per acre at 4% interest, or $32 per acre — and invest it in cover crops that decrease soil compaction," Hoorman says. "Water can't flow vertically or horizontally to tile lines in compacted soils and cover-crop roots create macropores to move excess water to your existing tile."
Decreased Soil Compaction: Deep-rooted and/or fibrous grass cover crops break up vertical and horizontal soil compaction. Farmers typically deep-rip their soils at a cost of $30 to $35 per acre. Hoorman says spending the same money annually on cover crops adds soil organic matter and increases soil productivity. He adds that research is showing that soil compaction is due to a lack of living roots in the soil.
Nutrient Recycling: Soil compaction and poor drainage may account for 40% to 60% of nitrogen losses through denitrification in silty clay soils. Hoorman says cover crops improve microbial growth and nutrient recycling, which accounts for the majority of nutrients supplied to crops.
"Cover crops act like an elevator to move nutrients from the subsoil and keep the nutrients recycling in the topsoil," he says. "Economically, every 1% of soil organic matter is worth about $600 in soil nutrients.
"A good cover crop may add .05% to 0.1% soil organic matter every year, or $30 to $60 in stored nutrients. Several years of continuously growing cover crops may lower your fertilizer bill by 25%.
Pesticides: There are two ways to fight weeds, Hoorman says.
"One is to try to kill weeds with herbicides; the other way is to compete with the weeds for sunlight, nutrients and water by planting cover crops," he says.
Hoorman says crop diseases like pythium, phytopthora and rhizoctonia thrive where the soil is poorly drained due to soil compaction. Growing cover crops improves drainage and reduces soil compaction.
While some insect infestations like cutworms, army worms and slugs may increase initially with cover crops, Hoorman says long-term no-tillers with cover crops report cutting annual herbicide costs by one-third and reduce root disease problems. But insect pest costs may increase slightly until natural predators are restored.
Environmental Cover-Crop Benefits: If farmers start no-tilling with cover crops, less fuel, tillage and machinery investments are needed, Hoorman says.
"Cover crops reduce soil erosion and result in less nutrient runoff and less flooding," he adds. "Increased soil organic matter improves the water-holding capacity of soil, which is an insurance policy against drought.
"Crops yields do increase with cover crops; however, the increased yields generally do not occur until soil management problems from excess tillage are corrected. In the long run, cover crops make farmers money by saving input costs, improving efficiency and eventually increasing crop yields."