Evaluation of nitrification inhibitor to improve fertilizer N use efficiency in potato crop

Two field experiments were conducted (a spring and an autumn) during 1996-9 7 to study the effect of application of two nitrification inhibitors (nitra pyrin and wax-coated CaC2) at two hi rates (100 and 250 kg N ha(-1)) on fer tilizer use efficiency (FUE), hi recovery, yield of potato (Solanium tubero sum L.), and to compare it with split application of N. The results reveale d that the treatment receiving inhibitors had more mineral hi accumulation than the treatment receiving no inhibitors in the active root zone (0-30 cm ) up to 65 days after sowing (DAS) Ammonium was a major fraction of mineral N in the treatments receiving inhibitors. DAS, the soil at 0-30 cm depth d id not show major differences in the mineral-hi status of treated and untre ated plots. However, at 60-90 cm and 90-120 cm depths, the treatment receiv ing no inhibitors contained higher NO3-N indicating greater NO3 leaching fr om the active zone. Maximum tuber yield and hi concentration was obtained a t low hi level treated with nitrification inhibitors followed by two split applications of 250 kg N ha(-1).