The Effect of Nitrification Inhibitor on Grain Yield of Wheat Cultivars and Some Soil Properties under Conventional and No-Tillage Systems

In agriculture, nitrogen fertilizer does not effectively absorb by plants. Several biological activities in the soil convert N into various compounds. Nitrogen oxide (N2O) is an influential greenhouse gas formed in soils due to nitrification and denitrification process. Nitrapyrin (NI) combined with ammonium (NH₄⁺) based fertilizers is an effective technique for minimizing the N loss in agricultural soils by regulating ammonia-oxidizing. This research was conducted during 2019-2020 to determine the effect of NI on nitrogen emissions in soil and crop yield of wheat cultivars at three urea (UR) levels, NI+urea (NIU), and control (CO) on two cultivars (Rakhshan and Pishgam) and two tillage systems (No tillage (NT) and conventional tillage (CT)). The highest amounts of NH₄⁺, NO3- and N2O were found at the stem elongation stage. While NIU fertilizer treatment yielded the highest NH₄⁺ (18.38 mg kg⁻¹), the UR fertilizer treatment yielded the highest NO3- (25.96 mg kg⁻¹) and N2O (0.0192 kg N2O-N ha⁻¹ day⁻¹). At all developmental stages in the CT and NT systems, the NIU treatment decreased the average nitrification of NH₄⁺ and its conversion to NO3- by 27.81 and 15.45%, respectively. Our findings, thus, showed that NI application in conjunction with UR could highly reduce N2O emissions. In addition to the favorable economic impact, increasing N availability in the soil through minimizing nitrification by NI may reduce detrimental environmental consequences on water resources and greenhouse gas emissions.