A Holistic Approach to Crop Rotations for the Central Plains

The 20 million acres of the Central Great Plains' amber waves of grain are changing dramatically. Some farmers are growing more--and different--crops because those crops make more efficient use of the limited water.

Growers are finding that alternative rotations--based on findings of Agricultural Research Servicescientists--can be 20 to 40 percent more profitable than the traditional wheat-fallow system. In that system, growers plant one crop every other year and leave the soil bare for a year to store water.

Wheat-fallow systems use only 40 percent of the average 14 to 18 inches of annual rainfall, but continuous cropping soaks up nearly 80 percent, according to Randy L. Anderson at ARS' Central Great Plains Research Station in Akron, Colo. For nine years, he and colleagues have tested 20 dryland crop rotation and tillage systems in seeking the best alternatives to wheat-fallow.

The researchers have found that growers could successfully crop continuously in years with normal or more precipitation by using a cycle of four crops and alternating high- and low-water use crops. For example, continuous cropping with wheat-corn-proso millet and either field peas, another wheat crop, or fallow doubles the land's productivity compared to wheat-fallow.

This systems approach, based on ecological trends in and on the soil, still provides for crops' water needs. And the crop diversity encourages soil microbes that make the ecosystem more sustainable over the long haul.

The researchers have improved water use so well, they're nearing their goal--a crop every year. They're still working on rotations that succeed in dry years. One option they're exploring is a forage crop or green fallow. Both use less water than the current crops--wheat, corn, millet and sunflowers.

For more details, see the story in the November issue of Agricultural Research magazine and on the web at:

http://www.ars.usda.gov/is/AR/archive/nov99/falls1199.htm

ARS is the major research arm of the U.S. Department of Agriculture.

Scientific contact: Randy L. Anderson, ARS Central Great Plains Research Station, Akron, Colo., phone (970) 345-2259, fax (970) 345-2088, [email protected].