Nitrogen Dynamics in Rice under Rice-Wheat Cropping System at Khumaltar Condition

  • Y. G. Khadka Nepal Agriculture Research Council (NARC), Soil Science Division, Khumaltar: Lalitpur


Nitrogen fertilization is a key input in increasing rice and other crop production in the world. Realizing the issue, nitrogen dynamics Lalitpur, Central Nepal was studied in long-term experiment under rice-wheat cropping system at rainfed lowland condition of Khumaltar The first objective of the experiment was to assess the contribution of organic, inorganic and biological nitrogen fixation (BNF) for the better nitrogen cycling and  utilization of added and residual nitrogen by crops. The second objective was to quantify the  N03- -N and  NH4+ -N in puddled soil at different soil depths and growth stages of rice in rotation with rice based wheat-cropping pattern.The nitrogen (N) level was used 0,50, and 100 kg N per ha The  NH4+ -N and  N03- -N dynamic in three soil depth (0-15, 15-30 and 30-60 cm) were monitored and crop performance evaluated in terms of grain and straw yield.The rice grain and straw yield were observed in the higher N-addition and incorporation of soybean stubble.The  N03- -N and  NH4+ -N in the soil were also higher in the soybean incorporation treatment than in other treatments. Higher  NH4+ -N was absorbed at maximum tillering stage than after rice harvest.