Abstract
Phosphorus (P) fixation by clay samples containing montmorillonite (90%), beidellite (90%), vermiculite (90%), kaolinite (50-90%) and x-ray amorphous material as affected by P sources and water regimes was studied in the laboratories of Land Resources Section, National Agricultural Research Centre, Islamabad, Pakistan. Fixation of P was significantly greater in case of alternate flooding and drying than that for continuous flooding. Fixation was the least in case of montmorillonite and the maximum in case of x-ray amorphous material. However, there were nonsignificant differences in P fixation among x-ray amorphous material, beidellite, vermiculite and kaolinite. There was non-significant difference in P fixation from ammonium dihydrogen phosphate, potassium dihydrogen phosphate and calcium monohydrogen phosphate P sources.
