Rotation but not intercropping translates soil nitrogen to crop uptake: A meta-analysis

Reducing reliance on industrial nitrogen (N) fertilizers requires alternative strategies that maintain crop productivity. Simultaneous (intercropping) and sequential (rotation) crop diversification both enrich soil N pools but may differ in crop N capture. Here, we synthesize 3,293 paired observations from 313 field experiments from major grain cropping systems to test whether intercropping or rotation better translates soil N to crop nutrition. Both intercropping and rotation increased soil total (~8%), available (~13%), and microbial biomass (~16%) N relative to monoculture. However, while rotation increased plant N uptake (~20%), intercropping showed no effect despite similar soil N enrichment. Both cropping systems increased yields substantially (intercropping +21%, rotation +10%), indicating intercropping delivers productivity through mechanisms other than enhanced crop N. These findings demonstrate that diversification strategies are not functionally equivalent and that rotation should be prioritized for crop N self-sufficiency, while intercropping should be prioritized for land-use efficiency and productivity.