Unveiling the effects of diversified prairies on wheat nutrition, phenology and growth in strip intercropping

Crop diversification and perennialization ( i.e. , transition from single-season crops to longer-term plant covers) are promising strategies for sustaining agroecosystems productivity while reducing inputs (mineral fertilizers, pesticides). However, their implementation remains limited under current practices, and requires a better understanding of plant-plant interactions that can either boost or hinder crop development. To advance crop diversification and perennialization, we propose associating perennial, multispecies covers of native prairie species with annual crops in fine-scale strip intercropping systems termed “agroprairies”. In a field experiment, we cultivated four varieties of wheat in monoculture or associated with four functional types of prairies that differed in the resource-use strategy of their species and in legume proportion. These treatments were crossed with the use or not of mineral nitrogen (N) fertilization. Our results show significant positive or negative effects of prairie strips on wheat nutrition, phenology, growth and biomass production, depending on prairie type, wheat variety and N fertilization. We suggest that resource-acquisitive trait syndrome and higher proportion of legumes in the prairie strips can significantly enhance wheat response to prairie (logRR, i.e. , the logarithm of the ratio of wheat outcome in agroprairie to that in monoculture, increases from −0.10 to 0.02 for leaf N, and from −0.22 to 0.04 for maximal height). Conversely, N fertilization tends to make the effects of prairies on wheat development more negative (logRR decreases from 0.01 to −0.11 for leaf N). Overall, this study opens up promising avenues for further developing trait-based approaches to design low-input, perennial and diversified cropping systems.