Soybean Yield Increases When Maize Is Included in the Cropping System

Abstract

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.