Evaluation of nitrapyrin in lab and on-field of bitter gourd production

Low efficiency and high leaching risk of nitrogen fertilizer in subtropics are of concern both agronomically and environmentally. Improvement of fertilizer itself by addition of nitrification inhibitor to N granules is a promising solution. Experiments were carried out to evaluate the performance of different formulations and concentrations of nitrapyrin on nitrogen transformation in soil fertilized with NO3-- and NH4+-N under both laboratory and field cultivated with bitter gourd. The optimal application rate of nitrapyrin and blend method with solid fertilizer was screened in lab. In the same incubation condition, responses of NO3--N and NH4+-N concentration in the soil to the addition of nitrapyrin at different concentrations (0.5, 1.0 and 3.0%) and time course (a month) as well as nitrapyrin formulations (emulsion and powder) were measured. The results showed that both nitrapyrin formulations slowed down conversion rate of NH4+-N to NO3--N in the soil fertilized with N in NO3-- and NH4+-N 1:1 ratio fertilizer. 0.5% application rate of nitrapyrin effectively delayed nitrification in lab condition when blended with solid N granules, with 44.2-56.6% NH4+-N transformation inhibited in the end of incubation. Increased nitrapyrin concentrations extended the presence of NH4+-N in soil more strongly, with 55.9-61.0% NH4+-N nitrification inhibited by nitrapyrin in 1.0% dosage and 64.5-68.1% in 3.0% dosage. There was no statistically significant difference between the two methods. The field performance of nitrapyrin-containing N fertilizer was estimated in bitter gourd production and more fruit yield was obtained with reduced rate. This study explored the feasibility of combining nitrapyrin with compound fertilizer to improve crops growth ecologic- and-agronomic friendly, revealing a potential to increasing NUE of crops and decreasing N loss by new fertilizer in bitter gourd production.