Intercropping efficiently utilizes phosphorus resource in soil via different strategies mediated by crop traits and species combination

Background and aims Understanding how long-term intercropping and phosphorus (P)-fertilizer application affect soil P fractions through P-acquisition strategies is critical to maintaining soil P balance in agroecosystems. Methods We established a long-term field experiment with three P-fertilizer application rates (0, 40, and 80 kg P ha −1 ) and continuously used four intercropping systems of chickpea/maize, faba bean/maize, oilseed rape/maize, soybean/maize and corresponding five monocultures in 2009. We measured aboveground biomass, shoot P content, soil P fractions, P-related root physiological traits, and soil microbe-related parameters of crop species in 2020. We also calculated the apparent soil P balance (P input into soil minus P harvested from crops) using data from 2009 to 2020. Results Intercropping enhanced aboveground biomass and shoot P content by 31.2% and 49.4% compared with the weighted means of corresponding monocultures, respectively; intercropping decreased the apparent soil P balance by 37.8% compared with monocultures across three P-fertilizer application rates. Over the 12-year period, chickpea/maize and soybean/maize intercropping systems significantly decreased the soil organic P concentration compared with sole maize; faba bean/maize and oilseed rape/maize intercropping systems significantly decreased soil non-labile P but increased organic P and labile P pool relative to sole maize. Rhizosheath phosphatases and carboxylates (proxied by leaf manganese concentration) might contribute to the depletion of sparingly-available soil P (organic P or non-labile P) in different crop combinations. Conclusion The higher rhizosheath acid phosphatase activities and carboxylate concentrations may correlate with efficient utilization of sparingly-available soil P resources in intercropping; effective P-fertilizer input enhanced soil P availability and decreased the P surplus in soil which is crucial to enhance crop P uptake.