[Chemical depletion of cumulative phosphorus in soils].

Cumulative phosphorus was defined as the phosphorus which was unavailable for plants and accumulated in soils fertilizer application. In this paper, chemical depletion of cumulative phosphorus in soils was studied by methods of batch equilibrium, kinetic, and anionic exchange resin membrane. The results showed that desorption amount of cumulative P increased with time increasing, and the desorption process was consonant with second-order kinetic equation. Release rate of P in different treatments was in order of PK > NPK > NK. The amount and rate of P released from red soil were higher than those of Fluvio-aquic soil. Desorbed P was significantly correlated with soil available P and P uptake by Plant. The maximum utilization of cumulative P in soils was about 45% of total phosphorus.