Abstract

                                A laboratory study was conducted to evaluate the effect of different factors on ammonia volatilization losses in flooded alkali soils (ESP 26 & 82). Incubation studies in these soils showed that the losses were largely governed by pH/alkalinity of the system. The duration of presubmergence decreased the cumulative ammonia volatilization losses from 19.2 to 13.5 per cent in ESP 26 soil and 22.5 to 16.0 per cent in ESP 82 soil at 0.5 and 10 cm floodwater depths, respectively. Flooding of the soil decreased the soil pH resulting in lower losses from 23.9 to 16.9 per cent in ESP 26 soil and 27.8 to 19.3 per cent in ESP 26 soil and 27.8 to 19.3 per cent in ESP 82 soil. The cumulative ammonia losses were maximum in the control treatment followed by Dhaincha straw, FYM, Rice husk and Wheat straw, varied from 8.1 to 16.9 per cent in ESP 26 soil and 9.0 to 20.5 per cent in ESP 82 soil. respectively. The floodwater NHi+, ptt and Cos" + HCO in all the experiments followed the same trend in which the losses occurred.

Key words : Ammonia volatilization losses. floodwater NH4 N. pH and CO3" + HCO3', incubation studies, sodic soils, urea