Luxury Absorption of Phosphorus Exists in Maize When Intercropping with Legumes or Oilseed Rape—Covering Different Locations and Years

Abstract

Rational regulation of phosphorus (P) use in the soil−rhizosphere−plant system is challenging in the development of sustainable, intensive, and healthy agriculture. Rational maize (Zea mays L.) based intercropping with legumes/oilseed rape across six experimental sites from 2008 to 2017 proved advantageous over monoculture in terms of both maize biomass production and P uptake. The partial land equivalent ratio (PLER) for P uptake by intercropped maize averaged from 0.58 to 0.92, which was significantly higher than that for biomass production (0.51−0.78), indicating that the advantage of P acquisition by intercropped maize was superior to that of biomass accumulation. It was the excessive accumulation of P in intercropped maize compared to monoculture, especially higher P concentrations in grains that led to the superior P acquisition advantage and luxury absorption of P. P concentrations in maize grains were significantly increased from 1.89−2.91 mg kg−1 in monoculture to 2.09−3.65 mg kg−1, in intercropping, by 8.3%−25.5%. The plant internal P use efficiency of maize was significantly decreased from the initial 411.7−775.7 kg kg−1 in monoculture to 345.7−710.4 kg kg−1 in intercropping by 4.9%−16.0%, and 100 kg maize grain P quantities were significantly increased from 0.25−0.46 kg to 0.27−0.54 kg by 7.0%−17.4%. Rational fertilizer P input maximized maize yields and P use without decreasing the interspecific ecological advantages and harvest indexes of grain yields and P. These findings promoted better understanding of P allocation status within maize plants, and yield and P acquisition advantages through the exploitation of the biological potential of plants for the efficient utilization of P resources in diverse species combinations.

Keywords

• intercropping
• facilitation
• niche complementarity
• phosphorus use efficiency
• luxury absorption
• harvest index