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

Ensuring sustainable food production while preserving biodiversity and ecosystem services under extreme weather is a challenge. We evaluated whether intercropping could enhance the yield, feed quality, and stability of crop production while also provisioning habitat for beneficial arthropods which could improve ecosystem services like pest predation. The study was conducted across two weather contexts at Brookings, SD, in 2023, with Planting A being cooler at germination, warmer at flowering, and generally drier than Planting B. Treatments included oat and pea monocultures, an oat-pea biculture, and in Planting A, an oat-pea-flax triculture. Overall grain yields were 2247 ± 151 kg ha⁻¹, 2498 ± 109 kg ha⁻¹, and 1423 ± 158 kg ha⁻¹ for oat-pea, oat, and pea, respectively. Yields of monocultures varied between the two weather contexts, with 30.4 % and 113 % higher yields of oats and peas in Planting B versus Planting A. However, the biculture yields were not different across weather conditions (p = 0.3). The bi- and tri-cultures were at least as land-use efficient as monocultures while providing stable productivity and feed quality even under heat-stressed conditions. The oat-pea mix also 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. Both polycultures improved the habitat for predatory arthropods and effectively suppressed weeds. Our findings suggest that intercropping could improve the productivity, stability, and long-term sustainability of feed grain production.