| Application of nitrification inhibitors（NIs） is an effective way to reduce nitrate leaching losses and emission of nitrogen oxides, thus to improve nitrogen fertilizer utilization efficiency. An incubation experiment was conducted to investigate the nitrification inhibition effect of nitrapyrins under dark condition in sandy and clayey soils at 25 ℃. Two nitrapyrin formulations, EC（Emulsifiable Concentrates） and EW（Emulsion in Water）, were obtained to study the nitrapyrin effect on nitrification. The results indicated that during 30 days of incubation, both EC and EW had higher nitrification inhibition efficiency in sandy soil than in clayey soil. Nitrification inhibition rates for EC were 55.6%~91.4% in sandy soils and 18.5%~50.9% in clayey soils. Nitrate nitrogen contents decreased significantly with the increase of EC concentration in both sandy and clayey soils. Nitrification inhibition rates for EW were 40.0%~79.0% in sandy soils and 35.7%~53.3% in clayey soils. EW concentration significantly affected the nitrification rate in sandy soils, but not in clayey soils. The optimal EC and EW concentrations for nitrate inhibition were 0.3% of nitrogen rate for both sandy and clayey soils. Under optimal inhibition rate, EC had higher nitrification inhibition efficiency than EW in sandy soil, but the opposite was true in the clayey soils. |
