几种典型除草剂对冬麦田N20排放及其相关土壤生化因子的影响

通过田间原位观测试验，研究了几种典型除草剂单，混施对冬麦田N2O排放及其土壤生化因子的影响。结果表明：在除草剂施用后的10d内，乙草胺和混剂苯磺隆＋精嗯唑禾草灵都显著抑制了N2O的排放（P〈0．05），其N：O排放通量均值较对照降低了50％左右，精嗯唑禾草灵和苯磺隆处理N2O排放通量均值分别比对照减少28．6％和26．0％，但未达到显著水平（P〉0．05）；在余下的测定期内，乙草胺、苯磺隆、精嗯唑禾草灵和混剂苯磺隆＋精嗯唑禾草灵对麦田N2O排放都无显著影响，其NzO排放通量均值分别为对照的95.3％、101．8％、92．5％和88．7％。乙草胺对土壤脲酶活性一直有激活作用（P〈0．05），精嗯唑禾草灵和混剂苯磺隆＋精嗯唑禾草灵表现为抑制激活交替作用，而苯磺隆对土壤脲酶活性基本无影响。在除草剂施用后的10d内，N：O排放通量与土壤水分WFPS（P〈0．01）、土壤反硝化细菌数量（P〈0．01）以及土壤氨氧化细菌数量（氏0．05）呈显著正相关关系，与可溶性有机碳含量呈显著负相关关系（P（0．05），与土壤硝化细菌、土壤硝态氮和铵态氮含量以及脲酶活性无显著相关关系（P〉0．05）。乙草胺和混剂苯磺隆＋精嗯唑禾草灵能显著降低麦田N20的排放，主要源于明显降低了土壤中反硝化细菌数量，混剂苯磺隆＋精噫唑禾草灵还明显降低了氨氧化细菌数量。苯磺隆和精嗯唑禾草灵对麦田N20排放无显著影响，主要是对氨氧化细菌和反硝化细菌表现为促进抑制的交替作用。

Effects of Herbicides on N20 Emissions and Soil Biochemical Parameters in Winter-Wheat Field

Research has shown that herbicides may inhibit non-target soil microbes and their biochemical processes. Here we conducted an experiment to examine the effects of herbicide applications on N20 emissions and related biochemical parameters in a winter-wheat soil. Applying acetochlor（AC） and tribenuron-methyl （TBM） and fenoxaprop-P-ethyl （FE） mixture significantly decreased N20 emissions by approximately 50% in the first ten days following herbicides application （P〈O.05）, while fenoxaprop-P-ethyl （FE） or tribenuron-methyl （TBM） alone reduce N20 emissions by 28.6% and 26.0%, respectively, compared to the control, but they were not statistically significant （P〉0.05）. For the remaining sampling days, AC, TBM, FE and TBM＋ FE all had no significant effects on N20 emissions. The average N20 flux was respectively 95.3%, 101.8%, 92.5% and 88.7% of the control. Soil urease activity was always enhanced by AC during measurement period（P〈0.05 ）, while was inhibited initially but stimulated afterwards by FE or TBM＋ FE. TBM did not influence urease activity（P〉0.05 ）. In the first ten days of herbicide application, N20 fluxes were correlated positively with soil water-filled pore space （WFPS）, denitrifying bacteria （ DNB ） （P〈0.01 ） and ammonia-oxidizing bacteria （AOB） （P〈0.05）, but negatively with soil dissolved organic carbon （ DOC ） （P〈 0.05）. Due to less abundance of DNB in AC and TBM＋FE plots and AOB in TBM＋FE plots, N20 emissions were significantly inhibited in AC and TBM＋FE. TBM or FE had no significant effects on N20 emissions from the wheat field, mainly due to their alternative promotion and inhibition of AOB and DNB. More studies are necessary to better understand the effects and mechanisms of different herbicides on N20 emis-