Farmers are starting to overcome some misperceptions about cover crops, which include the myths that they cost too much and aren’t profitable, an Ohio State University Extension educator says.
"Farmers who start no-tilling with cover crops use less fuel, less tillage, and less machinery," James Hoorman, Ohio State University Extension cover crops and water quality educator, says. "Cover crops lower soil erosion, which reduces nutrient runoff and flooding. Increased soil organic matter increases the water holding capacity of soil, which is an insurance policy against drought," Hoorman says.
"Barriers to using cover crops include high seed costs and not knowing how to manage them, as well as the extra labor, chemicals and machinery trips to plant and kill the cover crop," he says.“Cover crop seed may cost as little as $5 to more than $50 per acre.
“On the low side, oats, bin-run wheat and soybeans can be used. On the high side, legumes like cowpeas and winter peas, can be used for home-grown nitrogen. At 80 cents to $1.20 per pound and at 40 to 50 pounds per acre, it gets a little pricey. 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 are reducing the risk of establishing cover crops. Understanding the life cycle, limitations and benefits of each plant and experience helps no-tillers grow 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 does if cover crops will increase yields or lower costs. Unfortunately, crop yields and returns may be slow to improve until soil drainage and compaction improve. That's why the perceived value of cover crops varies from farm to farm.”
Cover crops work best on farms that work closely with Mother Nature. Cover crops and no-till farming mimic the nature cycle of keeping plants growing year round. Cover crops feed the microbes that feed the following crop.
“Farms that grow more plants year round — livestock farms, hay, pasture and wheat fields — will respond faster than a typical corn-soybean farm that only grows a cover crop once every 5 years,” Hoorman says.
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 a large amounts of commercial fertilizer and herbicides, insecticides and fungicides may react more slowly to the benefits of using cover crops, because they are less reliant on microbial life for supplying nutrients to their crops,” he says.
Relying on chemical inputs comes at a price because the efficiency of commercial fertilizer decreases as the microbial life declines in the soil. While cover crops may not directly increase crop yields initially, they increase nutrient efficiency and decrease input costs.
A common myth among farmers is that corn benefits directly from fertilizer, Hoorman says. Most corn fertilizer is recycled through microbes first, so farmers actually fertilize the microbes and indirectly fertilize corn. As fertilizer and fuel cost increase, cover crops and no-till are economical because tillage, fuel consumption, and chemical inputs of fertilizer and pesticides become more expensive.
Cover crops improve farm economics through better drainage, decreased soil compaction, nutrient recycling and weed control.
“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 costs $800 per acre to split your tile lines on 40 foot spacing. 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.
“Water cannot 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. Deep ripping fields can cost $30 to $35 per acre. Spending that money annually on cover crops adds soil organic matter and increases soil productivity. Research is showing that soil compaction is due to a lack of living roots in the soil.
“Soil compaction and poor drainage may account for 40 to 60 percent 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.
“Economically, every one percent soil organic matter is worth about $600 in nitrogen, phosphorus, potassium and sulfur,” Hoorman says. “A good cover crop may add 0.05% to 0.1% of 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%.”
Hoorman says farmers can fight weeds with herbicides or have cover crops compete with weeds for sunlight, nutrients and water. Crop diseases like phythium, phyphthora, and rhizoctonia thrive where the soil is poorly drained due to soil compaction.
Growing cover crops improves drainage and reduces soil compaction. Initially, some insect infestations — such as cutworms, army worms and slugs — may increase with cover crops.
“Long-term no-tillers who use cover crops report cutting their annual herbicide costs by 33% and reducing root disease problems,” Hoorman says. “However, insect pest costs may increase slightly until natural predators are restored.”
"Crop yields do increase with cover crops," Hoorman says. "However, an increase in crop yields generally does not occur until the soil compaction and poor drainage caused by excess tillage are corrected. In the long run, cover crops make no-tillers money by cutting input costs, improving efficiency and eventually increasing crop yields."