Implications of Pea–Barley-Mixed Cropping on Gross Margin, Root Rot Infestation, and Nitrogen Supply—A Swiss Case Study

A growing demand for plant-based proteins and renewable nitrogen supplies has necessitated an intensification of legume cultivation in Europe. However, the cultivation of grain legumes is inherently exposed to various risks, including lodging and fungal infections. Mixed cropping of pea (Pisum sativum L.) and barley (Hordeum vulgare L.) presents a promising approach to increase plant-based protein production while also improving yield stability. We performed a multi-environment-mixed cropping comparison with pure pea and pure barley to determine the effects of the cultivation method on root rot resistance, N supply in successive crops, grain yield, and economic performance. While the economic performance was similar for pure pea and mixed cropping, we observed a lower variability of the farmer's gross margin in mixed cropping compared with pure cropping across 3 years and two locations. Especially in seasons with high precipitation, the mixed cropping approach prevented lodging and harvest losses. The N supply in the successive crop was equal or higher in mixed cropping compared with pure pea cropping. No variation in the pea root rot infestation levels was observed between mixed and pure cropping, indicating a general demand for resistance breeding. Our experiment indicated genotype-specific effects on the gross margin in regard to culture (pure pea and mixed cropping). Leafy genotypes in particular demonstrate substantial performance gains when cultivated in mixed cropping systems. The conclusion is that mixed cropping leads to similarly positive crop rotation nitrogen effects as pure pea cropping, with the advantage of reduced gross margin and yield variability.