Get healthy soil by planting cover crops and rotating
Date Modified: 09/11/2013 10:26 AM
A growing number of farmers throughout Minnesota have "discovered the cover" — and for some very good reasons. They're increasingly recognizing that by using cover crops and diverse rotations, it's possible to actually improve the health and function of their soil.
The principles of building healthy soils are the same everywhere — stop tilling or minimize tillage of the soil and switch from a monoculture crop rotation to one with a diversity of crops that should include cover crops. These principles serve to create the habitat for soil microbes to flourish, enabling the rejuvenation of the soil.
Keeping the soil covered and growing with living roots is a critical component in improving the health and function of the soil in almost all farming operations. Because soil microbes need a food source longer than most cash crops can provide, using cover crops can meet this need later in the fall and earlier in the spring.
It also is widely known that maintaining soil cover controls erosion. In addition, the plant residue has the added benefit of cooling the soil in the summer and reducing water loss through evaporation — all of which help reduce plant stress.
While the path to soil health is different on each farm, understanding how management decisions affect soil function will help producer gain confidence as they implement these soil health management principles on their farms.
Managing cover crops in a soil health management system, which can be one of the biggest management challenges farmers face, is a good example. Farmers not familiar with how mixtures of cover crops work together might ask, "Why would I want to plant a cover crop that uses up all my water?"
But using diverse annual cropping rotations and cover crop combinations increase soil organic matter, and for each 1 percent in organic matter, there can be a 50 percent increase in water holding capacity with up to 30 pounds an acre more of available nitrogen.
A recent survey by the USDA North Central Region Sustainable Agriculture Research and Education program and the Conservation Technology Information Center of more than 750 farmers, primarily from the drought-stricken upper Mississippi River watershed, reported that farmers who planted corn after cover crops had a 9.6 percent increase in yield compared to side-by-side fields with no cover crops.
Likewise, soybean yields were improved 11.6 percent following cover crops, according to the survey.
So while it is true cover crops use some of the water in the soil profile, they simultaneously improve the soil health and structure by building soil aggregates, provide mulch that reduces evaporation and runoff losses, and break up subsoil to increase water recharge. By using cover crops, no-till and crop rotations, farmers are finding that their soil actually has more available water for their cash crops when those crops really need it.
So whether its drought, deluge or normal rainfall, improving soil health is a smart investment that will pay dividends on and off the farm for generations to come.
I am challenging Minnesota agriculture (private landowners) to come to the NRCS/SWCD conservation office to review the opportunities to incorporate cover crops into their farming operation in 2014.
For more information on soil health and cover crops visit the "Unlocks the Secrets in the Soil" web page at www.nrcs.usda.gov, or contact your local NRCS office.
— Dan Baloun is state conservationist in Minnesota for the NRCS