Research Links Crop Rotation to Yield Gains and Lower Emissions
University of Illinois researchers have quantified the effects of corn-soybean rotation on yields, soil health, and profits using advanced modeling and a decade of field data.
The study confirms that rotating corn after soybeans increases yield and reduces the need for nitrogen fertilizer.
The average yield gain for corn after soy was 6.4% at standard nitrogen levels. Researchers found soybean residue breaks down quickly, warming the soil and promoting nitrogen mineralization — aiding early corn growth.
Ziyi Li, the study’s lead author, said, “The more nitrogen you add, the less yield benefit you get from rotation. In some cases, the yield boost nearly disappears.”
The rotation helps reduce greenhouse gas emissions but reduces soil organic carbon due to fast soybean residue decay. While nitrogen leaching was lower during soybean years, it increased during corn years due to nitrogen release from soybean residue.
“These results underscore a key trade-off,” said Kaiyu Guan. “Rotation improves some sustainability metrics while compromising others, especially under typical fertilization practices.”
Economically, the rotation proved more profitable, offering up to $458 per acre more than continuous corn when nitrogen use was low and market conditions were typical. However, profitability shifts under high corn prices and high nitrogen rates.
The study encourages farmers to manage nitrogen use wisely and consider soil health impacts. “Our work gives farmers and policymakers a more holistic view of organic matter, nitrogen, and yield outcomes,” said co-author Andrew Margenot.
Funded by USDA, NASA, and other partners, the research bridges the gap between science and real-world farm decisions, offering tools to balance sustainability and productivity in modern agriculture.