Long-term biochar addition significantly decreases rice rhizosphere available phosphorus and its release risk to the environment

Abstract Phosphorus (P) availability, diffusion, and resupply processes can be altered by biochar addition in flooded rice rhizosphere, which controls the risk of P release to environment. However, there are few in-situ investigations these rhizospheric effects. To explore effects on soil high-resolution dialysis (HR-Peeper), diffusive gradients thin films (DGT), zymography techniques were used provide direct evidence rhizosphere at sub-millimeter scale. Long-term (9-years) field greenhouse pot experiments demonstrated that notably decreased soluble/labile Fe concentrations (vs. no addition; CK) based results Peeper, DGT, two-dimensional imaging labile fluxes. DGT-induced fluxes soil/sediment (DIFS) model sediment index (SPRRI) further indicated diffusion capacity from solid solution, thereby decreasing These dominated redox cycling hydrolysis Al (hydro)oxides greatly increased unavailable (Ca-P residual-P). Additionally, (without additional biochar) showed previous long-term significantly phosphatase activity, due an adaptive-enhancing response decrease zone. The study biogeochemical reactions may a new perspective better evaluate potential benefits agricultural soils. Graphical