Intercropping legumes and cereals increases phosphorus use efficiency; a meta-analysis

Aims: Intercropping cereals with legumes may achieve high crop yields at reduced input levels. Several studies have indicated that intercropping increases phosphorus use efficiency but no overarching analysis exists on the role of species traits and input levels. Here we synthesize the available information on P use efficiency in cereal/legume intercropping. Methods: Global data on yields, P uptake and nutrient input in cereal/legume mixtures were extracted from the literature and statistically analyzed. Co-variables explaining P uptake efficiency and yield were considered. Results: P uptake was substantially increased with an average value of LERP, the land equivalent ratio for P uptake, of 1.24, and an average NEP (observed P uptake minus expected P uptake) of 3.67 kg P ha−1. The conversion efficiency of P uptake to biomass decreased with P uptake and was lower in intercrops than in sole crops but the conversion efficiency to yield was not affected by intercropping. The P fertilizer requirement was 21% lower in intercrops than in sole crops for the same yields. Conclusions: Substantial improvements in land use efficiency and P uptake are obtained by cereal/legume intercropping. Cereal/legume intercropping has therefore potential to increase P fertilizer use efficiency in agriculture