Increased microbial activity contributes to phosphorus immobilization in the rhizosphere of wheat under elevated CO2

Abstract

Understanding phosphorus (P) transformation in the rhizosphere affected by elevated CO2 (eCO2) needs to underpin the plant-derived C flow and P relationship in the plant-soil-microbe continuum. A pot experiment was conducted in CO2-controlled environmental cabinets. Wheat (Triticum aestivum) plants were grown in a P-sufficient Vertisol soil and exposed to 380 or 800ppm CO2 for 6 weeks. Plants were labelled with 13CO2 under respective CO2 treatments. Elevated CO2 increased NaHCO3- and NaOH-extractable organic P (Po) in the rhizosphere by 160% and 53%, respectively. Consistently, eCO2 increased microbial C and respiration in the rhizosphere. Furthermore, the excess of 13C atom in roots and rhi..