3,5-二甲基吡唑对尿素氮转化及NO-3-Ｎ淋溶的影响

采用室内培养和田间试验相结合的方法，探讨了新型硝化抑制剂3,5-二甲基吡唑（DMP）对尿素氮转化及玉米田硝酸盐淋溶损失的影响.结果表明，DMP对尿素水解仅起短暂的抑制作用，但可在较长时间内显著抑制土壤铵的氧化，且随DMP用量的增加，抑制效应显著增强.培养第10 d时，DMP各处理 （0.002?5、0.01 及 0.025 g/kg）的土壤NH₊₄-Ｎ累积量分别比CK提高了5.17、9.36和11.04倍，而NO^-₃-Ｎ累积量于培养第14 d时差异最大，与CK相比分别降低了33.30%、61.19%和73.72%（p<0.01）.土壤NO^-_2-Ｎ只在尿素施用前期有少量累积，但第3 d DMP各处理土壤NO^-_2-Ｎ含量降低幅度达95.77%～96.13%；土壤矿质氮总量于10 d以后，随DMP用量的增加，显著降低，而DMP1处理的土壤微生物量N在培养14～56 d期间显著提高.连续2 a的玉米田间试验原位取土测定结果表明，2004和2005年，DMP的施用使作物根系密集层以下（40～100 cm）土层的NO^-₃-Ｎ累积总量分别比CK降低了28.77%和44.70%.因此，硝化抑制剂DMP与尿素配合施用是调控氮素转化、缓解氮肥污染的有效措施.

Effects of 3,5-Dimethylpyrazole on Soil Urea-N Transformation and NO-N Leaching

With the combination of incubation test and field experiment, the effects of the new nitrification inhibitor 3,5-dimethylpyrazole on urea-N transformation and NO3- leaching loss from corn field were studied. The results showed that DMP could temporally retard the hydrolysis of urea after its application, but strongly inhibit the process of ammonium oxidation for a longer time, and the inhibitory efficiency was enhanced with increasing DMP dose. Compared with CK, soil NH4+-N content in treatments DMP1 (0.0025 g/kg), DMP2 (0.01 g/kg) and DMP3 (0.025 g/kg) was increased by 5.17, 9.36 and 11.04 times on the 10th day of incubation, while soil NO3--N content was decreased by 33.30%, 61.19% and 73.72% on the 14th day, respectively. The application of DMP could also decrease soil NO2--N content by 95.77% ~ 96.13% on the 3rd day of incubation, increase soil microbial biomass N from 14d to 56d, and reduce the total amount of soil mineral-N significantly with increasing DMP dose after 10 days of incubation. The corn field experiment indicated that, compared with CK, the soil NO3--N content of 40 ~ 100 cm layer in treatment DMP was decreased by 28.77% and 44.70% in 2004 and 2005, respectively. DMP application might be an effective means for regulating urea-N transformation and mitigating nitrogen pollution.