Phosphorus requirements for sustainable agriculture in Asia and Oceania : proceedings of a symposium, 6-10 March 1989 / International Rice Research Institute. International Council of Scientific Unions. Phosphorus in agriculture Phosphorus in agriculture Soils Soils Plants Plants Sustainable agriculture Sustainable agriculture 631 INT 1990 A049 Or. [Manila? Philippines] : International Rice Research Institute, 1990. 1990. Text xvi, 478 p. :