Intercropping of non-leguminous crops improves soil biochemistry and crop productivity: a meta-analysis

Plant species-rich systems tend to be more productive than depauperate ones. In agroecosystems, increasing crop plant diversity by including legumes often increases soil nitrogen (N) and improves soil fertility; however, such generality in outcomes of non-leguminous crop mixture is unknown. Here, through a meta-analysis of 174 individual cases, we explored the current global research trend of intercropping of exclusively non-leguminous crops (IC_nl) and quantified its effect on agroecosystem productivity key metrics, for example crop plant health, soil chemistry, and microbial community under diverse experimental conditions. IC_nl increased plant biomass and disease suppression and provided a notable yield advantage over monocultures. In addition to phosphorus and potassium, IC_nl also increased plant-available soil N, which, along with increased soil microbial abundance, was positively associated with increased soil organic matter. These positive effects were more pronounced in experiments with long duration (> 1 yr), field soil conditions, and soil pH > 7. IC_nl improves several crop productivity metrics, which could augment sustainable crop production, particularly when practiced for a long duration and in alkaline soils.