Diverse cropping system rotations benefit both farmers and the environment
No-till producers of corn and soybeans often apply insecticides multiple times each growing season to reduce pests that can decimate crops. Widespread pesticide use can have significant negative impacts, including the elimination of beneficial insect predators and pollinators, losses to adjacent crops and contamination of groundwater.
In response, researchers at Pennsylvania State University sought to determine whether corn and soybean producers can use less insecticide and still maintain competitive yields. The researchers conducted a six-year comparison of two types of crop rotations under no-till production: standard corn-soybean rotation with preventive insecticides applied twice annually to suppress caterpillars and other pests, and a diverse mixture of corn, soybeans, winter wheat and other cover crops that used insecticides only as needed.
Using integrated pest management (IPM) to manage the high-diversity rotation, researchers scouted plots during the growing season, generally looking for damage on corn plants. They specifically quantified the damage to corn from slugs and caterpillars, the most consistently problematic pests in the mid-Atlantic region. They set traps to assess slug numbers and analyzed partially eaten caterpillars to estimate predatory ground beetle numbers. If pest populations got too high, they could have applied insecticides, but they needed to use them only once in six years.
The results of the study suggest that yields produced by the two systems were similar, with the more diverse rotations that promoted predatory insects averaging only about 10% reduced establishment of corn plants due to early season pests. This study showed that diversified crop rotations create conditions that promote beneficial predatory insects to combat pests. Considering the cost of multiple insecticide applications and a continued struggle with commodity prices, this research demonstrates that the high-diversity rotation supporting IPM can compete with a low-diversity system that includes pesticides. Farmers can reduce their reliance on insecticides to control early-season crop pests, such as caterpillars, and still produce competitive yields of corn and soybeans.
Link to full statement on website: http://landgrantimpacts.tamu.edu/impacts/show/6160