Yield, nitrogen, and water use benefits of diversifying crop rotations with specialty oilseeds

Authors: Scott, Drew; EBERLE, CARRIE - University Of Wyoming; Gesch, Russell - Russ; Schneider, Sharon; Weyers, Sharon; Johnson, Jane

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2021
Publication Date: 5/8/2021
Citation: Scott, D.A., Eberle, C., Gesch, R.W., Schneider, S.K., Weyers, S.L., Johnson, J.M. 2021. Yield, nitrogen, and water use benefits of diversifying crop rotations with specialty oilseeds. Agriculture, Ecosystems and Environment. 317(1). Article 107472. https://doi.org/10.1016/j.agee.2021.107472.
DOI: https://doi.org/10.1016/j.agee.2021.107472

Interpretive Summary: Agriculture in the Upper Midwest is threatened by widespread use of too few crops. Few crops in a rotation can lead to problems including pests, disease, greater fertilizer usage, and greater water usage. Rarely used (specialty) oilseed crops, such as canola, are a chance to increase the number of crop species grown in this region. Oils extracted from the seeds of specialty oilseed crops have many uses including cooking oils, dietary supplements, and cosmetics. Nine specialty oilseed crops, corn, and soybean were grown in three settings. The next year, traditional crops (corn, soybean, and wheat) were grown on the same land to identify the previous crop effect on yield, nitrogen availability, and water availability. Soybean and wheat yields were similar regardless of previous crop. Corn yields were lowest when corn was the previous crop. Corn yields following a specialty oilseed crop were similar to corn yields following soybean (the typical rotation used in the Midwest). Corn yields trended towards being greater following specialty oilseed crops compared to following soybeans. Yield patterns were in part explained by more available nitrogen and water following some specialty oilseed crops. Specialty oilseed crops in a rotation can add benefits such as providing pollinator forage, disrupting pests and pathogens, and reducing fertilizer and pesticide use. Results show that oilseed crops did not reduce yields of corn and soybean while saving water. This information will help growers, extension specialists, and agricultural consultants to better understand the impact of adding specialty oilseeds to traditional Midwestern cropping systems. This information will also be of interest the specialty oilseed industry.

Technical Abstract: Decreased agricultural diversity from extensive use of the corn (Zea mays L.)- soybean (Glycine max (L.) Merr.) rotation and occasional inclusion of spring wheat (Triticum aestivum L.), has threatened cropping system sustainability. Using specialty oilseeds crops to extend the corn-soybean rotation might improve yields and promote sustainability. We tested whether corn, soybean, and wheat yields would be improved in a rotation following oilseed crops versus corn or soybean. In Phase 1, replicated blocks of nine different flowering oilseeds and two traditional grain crops (corn and soybean) were grown. In phase 2, corn, soybean, and wheat were planted in replicated blocks perpendicular to the previous year crops. This 2-year rotation was repeated for three site-years, two in Morris, MN and one in Brookings, SD. Soil water balance was evaluated during Phase 1 of the rotation to determine seasonal water use. Potential N mineralization was measured in the spring prior to planting in a subset of phase 1 treatments (spring canola, cuphea, corn, and soybean). Linear mixed models were used to analyze Phase 2 corn, soybean and wheat yield responses to previous crop. N dynamics and water use responses to phase 1 crops were also analyzed with mixed models. Corn yield was higher with any previous crop other than corn. Soybean and wheat yields did not significantly respond to previous crop. Yield patterns were partially explained by N mineralization potential and previous crop water use. Spring canola treatments provided higher potential net nitrification compared to corn. Canola, camelina, borage, and crambe had lower seasonal water use than both corn and soybean in at least one site-year. This short-term study indicated that corn and soybean yields following specialty oilseed crops had similar yields to a traditional corn-soybean rotation. Further, oilseed crops in rotation provided additional environmental benefits.