As the 2007 harvest winds down, it is the perfect time to consider planting cover crops. Cover crops include small grains, grasses, legumes and forbs that help prevent soil erosion, cut fertilizer costs, reduce the need for herbicides and other pesticides, enhance soil health, conserve soil moisture and protect water quality.
To obtain winter-long protection, winter-hardy rye, wheat, triticale (a cross between wheat and rye), clover or Hairy vetch planted in the fall offer the best erosion protection. These plants provide fall and winter cover and regrow in the spring. Oats and spring wheat can be planted in early fall, but will winter kill.
Planting fall cover crops is most beneficial when low residue producing crops – like soybeans or corn silage – are grown on highly-erodible land. "To maximize soil erosion benefits, you should allow for 30 to 40 days of good growth before the first hard freeze," says Barb Stewart, state agronomist with USDA's Natural Resources Conservation Service in Des Moines.
Cover crops provide many benefits
Cover crops provide fall through spring benefits before they are removed by harvest, tillage, crimping and/or herbicides in preparation for the following crop. They can provide extra forage for livestock producers while still maintaining environmental benefits.
According to research by USDA's Agricultural Research Service, cover crops can capture 30% to 60% or more of the nitrogen that would be lost to tile drainage systems. "This research tells us that nitrogen captured by cover crops represents a savings in fertilizer expense," says Stewart.
Producers who planted cover crops one year ago reaped the benefits after heavy, oftentimes damaging rains hit much of Iowa last spring. Southwest Iowa farmer Tom Chambers witnessed the soil erosion protection provided by a rye cover crop last spring. After 6 inches of rain in two days in May, there was erosion everywhere, except on the hillsides where he planted rye in the fall.
Provides impressive protection of soil
"I was impressed with how well the ground was protected," says Chambers. "You have to seed soon enough after harvest to make sure you can get a good stand. If you've waited until all your fall work is done, then it's probably too late to get a good stand."
Stewart lists a few considerations when planting cover crops:
- Plant cover crops in a timely manner to establish a good stand in the fall.
Maintain an actively growing cover crop as late as feasible to maximize environmental benefits, while allowing time to prepare the field for the next crop.
To maximize nutrient recover, use deep-rooted species that will maintain growth when the most moisture is moving through the soil to subsurface drainage systems, April through June.
Use grasses that utilize more soil nitrogen, and legumes that utilize both nitrogen and phosphorus.
The combined canopy and surface cover should be 90% or greater.
Use plant species that enhance biofuel opportunities.
Use plant species that enhance forage opportunities for livestock producers and flowering legumes for pollinators.
Stewart says the cost of planting cover crops will be paid back in the improved soil health it generates. "For more information about cover crops, visit your local NRCS office," she says.