Effect of Phosphorus Application on the Transformation of Iron in Soil and Iron Nutrition of Rice under Two Soil Moisture Regimes

The effect of addition of phosphorus on dry matter yield and iron nutrition of rice (variety IR-8) at two moisture regimes, i e., field capacity and waterlogging and also on the transformation of native and applied iron was studied in a pot experiment. Addition of phosphate decreased available and reducible Fe while it had no effect on exchangeable Fe. With time, contents of available and reducible Fe decreased and increased, respectively, but not the exchangeable Fe. Moisture regimes generally enhanced the contents of all the forms of Fe and the increase was more pronounced under waterlogged situation. Application of Fe up to 25 ppm significantly changed the dry matter yield, its contents and uptake and at 50 ppm there was a decrease in these values. Significantly higher dry matter yield and uptake of Fe were recorded under waterlogged condition than at the field capacity. Interactions of Fe × P, moisture × Fe, moisture × P and moisture × Fe × P, were found, by and large, to have significant influence on dry matter yield, Fe content and its uptake.