Feed grain polycultures mitigate weather risk, support arthropods, and suppress weeds in the Western Corn Belt

Authors: Neupane, Dhurba; Osborne, Shannon; Roeder, Karl; Knoll, Avery; Ewing, Patrick

Submitted to: Agriculture, Ecosystems & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2025
Publication Date: 6/5/2025
Citation: Neupane, D., Osborne, S.L., Roeder, K.A., Knoll, A.E., Ewing, P.M. 2025. Feed grain polycultures mitigate weather risk, support arthropods, and suppress weeds in the Western Corn Belt. Agriculture, Ecosystems & Environment. 393. Article 109773. https://doi.org/10.1016/j.agee.2025.109773.
DOI: https://doi.org/10.1016/j.agee.2025.109773

Interpretive Summary: Planting mixtures of crops is a strategy for improving the productivity, stability, and resilience of cropping systems in the face of climate change. We examined the grain yield and stability, feed quality, and ecosystem services, such as weed suppression and predation of pest insects, of crop mixtures in two weather contexts with Planting A being cooler and drier, and Planting B being warmer and wetter. Overall, the results show that the oat-pea mixture produced a 58% higher grain yield than peas and a comparable yield to oats alone (2498 kg ha-1 for oats versus 2247 kg ha-1 for the oat-pea mix), and the protein content of mixed grain was higher than in monoculture. Additionally, monoculture yields varied by 30% (oats) to 110% (peas), whereas the oat-pea mix had a similar yield across both planting dates, illustrating the benefits of diversity even under poor growing conditions. Feed quality analysis found that the oat-pea mix had higher crude protein, similar acid detergent fiber and total digestible nutrients, and lower neutral detergent fiber than the oat grain alone. Moreover, the polyculture improved the habitat for predatory arthropods and effectively suppressed weeds. The findings from this study will be valuable for growers and agricultural researchers developing polyculture experiments with species and trait compatibility and the appropriate mixing ratio for optimal production.

Technical Abstract: Ensuring sustainable food production while preserving biodiversity and ecosystem services under climate variability is a challenge. We evaluated whether intercropping could enhance the yield, quality, and stability of crops while also provisioning habitat for beneficial arthropods which could improve ecosystem services like pest predation. In two weather contexts, a one-year polyculture study was conducted at Brookings, SD, in 2023, with Planting A being cooler and drier and Planting B being warmer and wetter. Results show that overall grain yields were 2247 ± 151, 2498 ± 109, and 1423 ± 158 kg ha-1 for oat-pea, oat, and pea, respectively. Yields of monocultures varied between the two weather conditions, with 30.4% and 113% higher yields of oats and peas in warmer and wetter Planting B compared to cooler and drier Planting A. However, the oat-pea intercrop yields were not different across weather conditions (p = 0.3). The oat-pea mix can be at least as efficient as monocultures in land use and has stable productivity and feed quality even under heat-stress conditions. We also observed that the oat-pea mix had higher crude protein, similar acid detergent fiber and total digestible nutrient, and lower neutral detergent fiber content versus the oat grain, while pea had the highest crude protein and lowest fiber content. Moreover, the polyculture improved the habitat for predatory arthropods and effectively suppressed weeds. Our findings suggest that intercropping could improve productivity and long-term sustainability of feed grain production, and this is a feasible approach to adding diversity to regional cropping systems.