Nitrogen supplying ability of some Philippine rice soils

The nitrogen-supplying power of eight Philippine rice soils was measured by consecutively growing six crops of IR 32 rice under flooded conditions in a greenhouse pot experiment. The dry matter yields or nitrogen uptake of rice were found to be highly positively correlated with the organic carbon and the total nitrogen contents of the soils, as well as with the amounts of ammonium released during an anaerobic incubation test at 30°C for 2 weeks. The results of the study bring out the usefulness of simple tests like organic carbon content and total nitrogen content of soils for predicting the nitrogen-supplying power to lowland rice