Interspecific facilitation of P acquisition in intercropping of maize with white lupin in two contrasting soils as influenced by different rates and forms of P supply

Abstract

This study of a maize-white lupin model cropping system was conducted to investigate the effects of rhizosphere-sharing of white lupin, a P-efficient plant, on growth and P accumulation of maize under different P rates and forms in two contrasting soils. With Regosol and Andosol, a 42-day pot experiment was conducted for 0P (no P addition), 50Pi, 100Pi (50 and 100 mg P kg−1 soil by NaHPO4⋅2H2O respectively), and 100Po (100 mg P kg−1 soil by phytate). Plant growth, P uptake, rhizosphere pH, and different P fractions were investigated. Complementary effects of intercropping for maize were observed in Regosol, but not in Andosol. Total P uptake by intercropped maize in 0P, 50Pi, and 100Po was elevated by 46, 37, and 65 %, respectively, compared to when it was grown as a monoculture. White lupin mobilized P from sparingly soluble forms. Thereby, maize plant enhanced its P accumulation as a result of access to these two fractions in mixed culture in Regosol, where strong root intermingling occurred among intercropped plants. Results suggest that the P mobilization strategy of white lupin from sparingly soluble P pools in soil can enhance the P acquisition efficiency of coexisting maize with P facilitation in this intercropping occurring in the direction of white lupin to maize. Achieving enhanced growth and P uptake by P-inefficient species in intercropping with white lupin is dependent on the type of soil in which those plants are grown.