Various forms of phosphorus viz.• adsorbed P, Al-P, Fe-P, Ca-P and reductant soluble-P in relation to varying soil pH, availability of P under air-dried and waterlogged condition and response to P application in saline-sodic soil under rice-wheat crop sequence were studied. Ca-P was observed as the most predominant P fraction followed by reductant soluble P, Fe-P, Al-P and adsorbed P in soil pH range of 72 to 10.3. Availability of P increased at the rate of 6.1 ppm and 7.5 ppm under air-dry and waterlogged condition respectively per unit increase in soil pH, showing only a slight increase in P availability due to waterlogging. In a pot experiment no response to added P was observed in saline-sodic soil amended with gypsum at the rate of 100 per cent of GR in rice and succeeding wheat crop due to high initial available P content of soil.
Forms of P, available P, waterlogging, gypsum, response
