有机无机配施下西北旱区麦田土壤N2O的排放特征及微生物特性

有机无机配施可为作物提供长效持续的营养物质来源,研究旱地农田有机无机配施带来的环境效应和土壤酶活性及微生物特性,对减少化肥面源污染,改善生态环境有重要意义.本试验以3个梯度氮水平(NO、N1、N2):0、150、300 kg·hm-2为主处理,单施化肥和有机无机配施(+M)为副处理,有机肥施用量为30 t·hm-2;测定了小麦生长季的温室气体N2O排放通量和土壤酶活性,硝态氮及铵态氮含量和土壤物理性质.结果表明,土壤N2O排放通量最高的为N2+M处理,排放通量达到0.190 4 mg·(m2·h)-1,N2+M处理较NO累计排放量提高了 255％;N2和N2+M处理N2O的排放通量和增温潜势高于N1和N1+M处理,而产量低于N1和N1+M处理;微生物量碳氮以N2+M处理分蘖期最多,分别为346.31 mg·kg-1和33.36 mg·kg-1;N2+M处理的土壤酶活性较高,其次是N2处理,NO和NO+M处理土壤酶活性较低;通径分析表明,铵态氮(NH4+-N)、土壤磷酸酶(AKP)和微生物量氮(MBN)对N2O排放通量的直接影响较大,其他间接影响较小可不予以考虑.研究旱地麦田有机无机配施的环境效益,与多方面因素相关,合理地配施有机肥可以平衡产量与土壤环境的综合效益.

Effects of Manure Combined Chemical Fertilizers on Soil N2O Emission and Microbial Characteristics of Wheat Crop System in Northwest Arid

The combined application of organic and inorganic fertilizers can provide long-term and sustainable sources of nutrients for farmland. It is of great significance to study the environmental effects and soil enzyme activity microbial characteristics of farmland soil under this fertilization method for the development of dryland soil fertilization measures. In this experiment, three gradient nitrogen levels (N0, N1, and N2:0, 150, and 300 kg·hm^-2, respectively) were used as the main treatment, and chemical fertilizer alone and the combined application of organic and inorganic fertilizer (+M) were used as the secondary treatment. The N₂O emission flux, soil enzyme activity, nitrate ammonium nitrogen content, and soil physical properties during the wheat growing season were measured. The results showed that the soil N₂O emission flux under the N2+M treatment was 0.1904 mg·(m²·h)^-1, which was 255% higher than that of the N0 treatment. The maximum microbial biomass C and N were 346.31 mg·kg^-1 and 33.36 mg·kg^-1, respectively, at the tillering stage when treated with N2+M. The soil enzyme activities under the N2+M treatments were highest, followed by those under the N2 treatments, and the soil enzyme activities under the N0 and N0+M treatments were lowest. Path analysis showed that the direct factors were ammonium nitrogen, AKP, and MBN, which had a greater contribution on N₂O emission flux; the effects from indirect factors were small and can be ignored. The emission flux and warming potential of N₂O in the N2 and N2+M treatments were higher than those in the N1 and N1+M treatments; however, the yield was lower than that in the N1 and N1+M treatments. The environmental benefits of organic and inorganic fertilizer application in dryland wheat fields are related to many factors. Rational application of organic fertilizer can balance the comprehensive benefits of yield and soil environment.