New research out of the University of Illinois looks at the long-term consequences of crop rotations including corn, soybean, and wheat crops, compared to less diverse rotations.

This study was conducted at the Northwestern Illinois Agricultural Research and Demonstration Center near Monmouth, IL, located in a region with “some of the most productive soils in the world” (ScienceDaily, 2018).  The team compared fields with continuous corn and soybean crops with those managed under a corn-soybean or corn-soybean-wheat rotation over 20 years.  They also considered whether or not a field was tilled.

Greenhouse gas emissions were measured in all plots for 4 consecutive years, including carbon dioxide, methane, and nitrous oxide.

Tillage and crop rotation were shown to have a significant impact on yields and greenhouse gas emissions.  Specifically, tillage increased yields of corn and soybeans, and both tillage and crop rotation decreased nitrous oxide emissions.

Some of the changes were substantial.  With a corn-soy rotation, corn yields were increased around 20%, AND nitrous oxide emissions of corn crops reduced by around 35%.  Soybeans crops in this plot showed a more modest yield increase of 7%, although similar emission reductions were not observed.

Interestingly, in terms of the yield-enhancing “rotation effect,” the corn-soy rotation delivers as great a yield increase as the more diverse, corn-soybean-wheat.

In addition to raising attainable yield goals and reducing net greenhouse gas emissions, diverse rotations also break weed, insect and plant disease cycles, generally lowering over time the need for pesticide applications and other control interventions.

Sources:

Gevan D. Behnke, Stacy M. Zuber, Cameron M. Pittelkow, Emerson D. Nafziger, María B. Villamil, “Long-term crop rotation and tillage effects on soil greenhouse gas emissions and crop production in Illinois, USA. Agriculture,” Ecosystems & Environment, 2018; 261: 62 DOI: 10.1016/j.agee.2018.03.007.

University of Illinois College of Agricultural, Consumer and Environmental Sciences. “Long-term study shows crop rotation decreases greenhouse gas emissions,” ScienceDaily, 23 May 2018.