Effects of different nitrification inhibitors on urea transformation | 不同硝化抑制剂对尿素转化的影响

Chinese. 比较不同硝化抑制剂在石灰性土壤上对氮素转化的抑制效果，旨在选择石灰性土壤上较理想的硝化抑制剂，为进一步提高氮素利用率、减少环境污染提供依据。以单纯施用尿素为对照，采用室内土壤培养试验法，将硝化抑制剂3,4-二甲基吡唑磷酸（DMPP）、双氰胺（DCD）、2-氨基-4-氯-6-甲基嘧啶（AM）和硫脲（TU）施入土壤，在培养一定时间（1~50 d）后采样，测定土壤的NH4+-N、NO3--N、NO2--N含量及pH和电导率（EC）。硝化抑制剂DMPP、DCD和AM 不仅能够有效延缓尿素的水解,显著抑制土壤中NH4+-N的氧化作用，而且能够较长时间保持较高的NH4+-N含量，使硝化作用延滞35~38 d。各硝化抑制剂（TU除外）处理明显推迟了NO3--N的释放高峰期，对硝化过程均表现出明显的抑制作用。各硝化抑制剂处理的NO3--N、NH4+-N、电导率和pH之间有显著的相关性，土壤NO3--N含量与EC值呈显著正相关（P0.05），而与pH值呈显著负相关(P0.05）；土壤NH4+-N含量与EC值和pH值的相关性则与NO3--N相反。在本试验条件下，TU未表现出对石灰性土壤氮损失的抑制效果，其他3种硝化抑制剂的抑制能力强弱顺序为DMPPDCDAM（P0.05）。

English. The research compared inhibitory effects of different nitrification inhibitors in calcareous soil to select ideal nitrification inhibitors in calcareous soil, improve further nitrogen utilization and prevent environmental pollution from N fertilization in crop production. This study was designed to compare the efficiency of four compounds, namely 3, 4-dimethylpyrazole phosphate (DMPP), dicyandiamide(DCD), 2-amino-4-chloro-6-metho-xypyrimidine (AM) and thiourea (TU) for inhibiting soil nitrification in laboratory incubation experiment. EC, pH and the content of NH4+-N, NO3--N and NO2--N were measured at different incubation time. Nitrification inhibitor DMPP, DCD and AM effectively slowed down the hydrolysis of urea, significantly inhibited NH4+-N oxidation in soil, maintained a high NH4+-N content for a long time and reduced possibilities of NO3- leaching and NO2--N accumulation. The inhibitor treatment significantly postponed the NO3--N release peak (except TU), and showed obvious inhibition effects for nitrification and improved the utilization of urea. Soil nitrate content, ammonium content, electronic conductivity and pH in soil of all treatments had a close relationship with each other. Soil nitrate content increased with the increase of EC values, while decreased with the increase of soil pH. Changes of soil ammonium nitrogen content and EC value, pH with incubation time were in the opposite trend with the nitrate nitrogen content. The order of the inhibition rate of tested nitrification inhibitors is DMPPDCDAM (P0.05).