Effect of soil applied natural and synthetic nitrification inhibitors on nitrogen transformations and nitrification inhibition in NW Himalayan region of Himachal Pradesh

Abstract

Usefulness of nitrification inhibitors (NIs) has been identified in reducing the soil nitrogen losses of applied N fertilizers. We conducted an incubation experiment to evaluate the effects of soil applied NIs on nitrogen transformations (NH & NO ) and NI in sandy clay loam soil. Powdered extracts of pomegranate rind, melia fruit, neem -1 cake were prepared and added in soil at concentration of 20 and 40 g kg soil, respec- -1 tively, while calcium carbide was added at 30 g kg soil. Sources of N, P and K were urea, single super phosphate (SSP), murate of potash (MOP) at the rate of 1.98, 3.50 -1 and 0.88 g pot, respectively. Sole application of urea was taken as the control o treatment. Treated soils were incubated at 25 C for 42 days. Results revealed that at the + -1 end of incubation, highest NH -N retention (126.30 mg N kg ) and total soil nitrogen 4 -1 -1 (TSN) (152.72 mg kg ) was recorded under CaC @ 30 g kg soil treatment. Maximum 2 - -1 -1 NO -N accumulation (42.26 mg N kg ) was associated with melia fruit @ 20 g kg soil 3 -1 treatment. Regarding the nitrification inhibition, treatment of neem cake 40 g kg soil recorded maximum nitrification inhibition (44.31 %). Amongst the different nitrifica- tion inhibitors tested, lowest levels of nitrified N (20.41 and 22.05%) were recorded -1 -1 under the application of CaC @30 g kg soil and neem cake @40 g kg , while the 2 maximum (54.5%) was observed in treatment comprising of urea alone (control). Eco- friendly and cost-effective plant based nitification inhibitors were identified superior as compared to synthetic on nitrification inhibition.