NITRATE-NITROGEN IN RICE-PLANTED AND UNPLANTED SUBMERGED SOILS

A greenhouse pot experiment was conducted with two different soils to measure the formation of NO3- -N in the presence and absence of rice p lants under submerged conditions. The amount of NO3- formation due to the presence of rice plants was determined by subtracting the values o f NO3- in unplanted soils from those in planted soils. Soil samples we re taken on 7, 14, 21, 28 and 35th day after transplanting/fertilizati on. It was observed in both the soils that up-to the 14th day, there w as practically no difference in NO3- contents between rice-planted and unplanted soils. However, from day 21 onwards it was clearly observed that rice roots play a positive role in increasing NO3- contens in su bmerged soils.