Uptake of soil and fertilizer phosphorus by several high yielding rice varieties

Seven high yielding rice varieties used in the experiment are IR5, IR8, IR20, IR22, Pelita 1/1, Pelita 1/2, and Dewi Ratih. The experiment is carried out in the glass house and using 32P-labelled superphosphate. Specific activity of the labelled fertilizer used is 0,25 mCi/gr P2O5. Results obtained from this work show that Pelita 1/2 and IR5 take up a higher phosphorus nutrient than the other varieties, but IR5 gives the lowest percentage of phosphorus in plant derived from fertilizer. The average of plant phosphorus derived from fertilizer is about 35 to 45%, depending on the varieties. The application of phosphorus fertilizer increases soil phosphorus uptake and soil phosphorus content in plant. The decrease of the increments of soil phosphorus content in plants starts at the application rate of 60 kg P2O5/ha and reaches its maximum at the rate of 90 kg P2O5/ha. (author)