Soybean Yield Increases When Maize Is Included in the Cropping System

Core Ideas Soybean yield with maize as previous crop was ≈10% higher than the average yield. Soybean yield with soybean as previous crop was ≈4% lower than the average yield. Monoculture is explained as producers not valued this impact in short term decisions.Soybean [ Glycine max (L.) Merr.] monoculture is the dominant cropping system in the Rio de la Plata region. Despite the benefits of crop rotation, monoculture systems are an actual problem in many soybean and maize ( Zea mays L.) production areas worldwide. Soybean monocultures are especially problematic because of their negative impact on soil quality. Regionally, there are only a few reports about soybean monocultures and yield improvement when maize is included in the rotation. We used a producer's database (849 records from 2009 to 2013) to evaluate the effect of maize–soybean rotation on soybean yields. Four frequent annual previous crop sequences where identified: winter fallow–maize, winter crop–maize, winter fallow–soybean, and winter crop–soybean. As all of them are unequally represented, a new database was generated using a bootstrap resampling with 1000 replicates. Each interaction was economically analyzed, generating a variable called the differential gross product (difference in gross product, in US$ ha –1 , with respect to the gross product average). Results indicate that crop rotation with maize has an agronomic and economic advantage. Soybean yield was ≈12% higher than the average when winter crop–maize was the previous crop, whereas it was ≈5% lower than the average when the previous crop was winter crop–soybean. Soybean following maize resulted in a gain in gross product of ≈125 US$ ha –1 . However, the relationship between areas of soybean and maize indicates local producers fail to profitably grow maize or are inadequately assessing the impact of its inclusion into the production system.