Residual effect of fertilizer phosphorus in lowland rice

To evaluate residual recoveries of fertilizer phosphorus (P) two field experiments were conducted in Quezon Province, Philippines during 1991 dry season, under irrigated condition. Average grain yield increase was 0.50–0.9 t/ha due to residual effects of inorganic fertilizer P, regardless of source. Residual effects of fertilizer P with Sesbania rostrata or alone increased grain yield by 0.3–1.0 t/ha over control. Significantly higher yields were obtained with S. rostrata fertilized with Morocco phospate Rock (MPR) and S. rostrata + MPR applied on rice than the control. Results revealed that there is a promising effect of residual P from the applied P sources in increasing rice grain yield. Total P uptake increased due to residual P from fertilizer P applied. Results suggest that increased P uptake increased dry matter and grain yield.