Abstracted from an article by Donna Farris
Farmers have known for centuries that monoculture of crops
results in pest infestations and depletion of soil
nutrients.
Before World War II, farmers routinely rotated to legumes, sod and other crops
to help solve these dilemmas.
In the 1950s and '60s, however, the rotation effect was thought to be tied to nitrogen, and farmers believed the answer lay in applying chemicals.
The biggest change in current thinking is that the beneficial rotation effect partially involves soil microbes that might be site specific.
In southeastern South Dakota, almost anything is a deviation from the standard rotation of corn and soybeans. But many farmers are reluctant to change due to new demands for corn and soybeans in fuel markets. Some are trying a two-year corn, one-year soybean rotation, but still see a lag in yields in the second year of corn. With increasing markets for ethanol, many growers want to go to continuous corn.
Rotation in both corn and soybean fields
can break the cycle of weeds, insects, nematodes and disease. The nutrients
removed from the soil by one plant can be replaced by the rotation of another.
Alternative crops include winter wheat, spring wheat, sunflower, safflower, rice
and field peas.
Safflower, an oilseed crop, is used primarily for vegetable oil and soft
margarine has potential for South Dakota. It is drought resistant, has a
deep root system able to reach down deep in the soil for the water and
nutrients.