proceedings of a symposium, 6-10 March 1989 International Rice Research Institute International Council of Scientific Unions text Manila? Philippines] International Rice Research Institute 1990 monographic xvi, 478 p. : ill. ; 23 cm. Phosphorus in agriculture Phosphorus in agriculture Soils Soils Plants Plants Sustainable agriculture Sustainable agriculture 631 INT 1990 A049 Or. 9712200027