Field practice has long proved that the application of straw ash on newly reclaimed paddy soils derived from the lacustrine deposit in the flooded areas of Li-Shia-Ho,Kiangsu,greatly increases the yields of wheat,barley and other upland crops.Field experimenter were conducted to compare the effect of superphosphate with straw ash as basic dressings at a same level of phosphate fertilizer.Results revealed that superphosphate has a similar effect as straw ash.Laboratory investigations gave evidences that fixation of available soil phosphorus takes place as the flooded soil dried out through reclamation and drainage.