Labile and recalcitrant carbon inputs differ in their effects on microbial phosphorus transformation in a flooded paddy soil with rice (Oryza sativa L.)

Abstract

Organic carbon (C) can greatly affect soil microbial activity and thus alter the nutrient availability in soil. However, little is known about the microbial-mediated P transformation processes with organic C inputs in flooded soils. This study used high-throughput sequencing technology to investigate the effects of labile (glucose) and recalcitrant (lignin) organic C inputs on P availability and microbial communities in the bulk and rhizosphere soil under rice growth, aiming to clarify the key microorganisms involved in soil P transformation. Glucose addition enhanced microbial P immobilization and decreased P availability in the rhizosphere soil, while lignin amendment increased available P concentration in bulk soil through increased soil pH and altered bacterial community. Organic C inputs stimulated the growth and cooperation of specific P-solubilizing bacteria (e.g., Acetobacter and Phenylobacterium), facilitating the transformation of non-labile P to labile P in bulk soils, but also stimulated the growth of Clostridium_sensu_stricto, immobilizing labile P into their biomass. Irrespective of C supply, soil P availability was correlated positively with the abundances of Phenylobacterium and Desulfosporosinus but negatively with those of Acetobacter, Clostridium_sensu_stricto, Clostridium_IV, Gluconacetobacter and Syntrophomonas. This study emphasized the contrasting effects of labile and recalcitrant C on microbial mechanisms of P transformation in a flooded paddy soil. These findings provide potential strategies for microbially mediated P management in paddy fields.