Maize productivity and yield stability in diversified cropping systems: Insights from a long-term regional network

Diverse crop rotations can enhance productivity and yield stability, perhaps by promoting soil microbial communities or increasing carbon sequestration and soil water availability. We used a decade of maize (Zea mays L.) yield data from the Minnesota Long-Term Agricultural Research Network to investigate legacy effects of crop-rotation diversity on total and yearly maize grain productivity and stability. Cropping systems evaluated included a maize–soybean [Glycine max (L.) Merr.] rotation (MS), a maize–soybean–wheat (Triticum aestivum L.) rotation (MSW), and a maize–soybean rotation plus a fall-planted rye (Secale cereale L.) cover crop (MS + CC). Average maize yield over a 10-year period was greatest in the MSW, followed by MS and then MS + CC rotation at the Waseca and Lamberton sites, while there was no difference in yield among systems at the Grand Rapids site. During drought years, however, maize yield was significantly lower in the MSW rotation at the Waseca and Lamberton sites. Maize yield stability was lower in the MSW compared to the MS with or without a cover crop at the Waseca and Lamberton sites. Only some of the results from this research support the general hypothesis that crop productivity and stability benefit from systems with greater crop rotational diversity. Our findings show the importance of long-term, multi-location research for understanding how cropping systems respond to increasingly variable weather and how strategies for diversification need to be site-specific.