Nitrogen transformations in soil and rhizosphere of rice plants

Summary Different nitrogen forms (ammoniacal, nitrite and nitrate nitrogen) were determined in a pot experiment during 14 weeks to detect the nitrogen transformations in the soil and rhizosphere of rice plants. The results showed that ammoniacal nitrogen generally increased up to the 6th week after flooding and decreased thereafter in organic manured and unmanured treatments. High nitrate figures were recorded throughout the experiment in organic manured treatments, while nitrite figures showed no considerable amounts throughout the experiment. The amount of Jiitrate-N continuously decreased in both planted and unplanted waterlogged treatments, but the rate of decrease was slower in planted than in unplanted treatments. The results also showed that nitrate content of normally irrigated soil was much higher than that detected in waterlogged soils.