甲嘧磺隆和炔草酯对土壤微生物呼吸强度和氮转化的影响

为探究除草剂对土壤微生物的毒性效应，以土壤微生物的呼吸强度和氮转化作为检测指标，分别考察了甲嘧磺隆和炔草酯对红壤、棕壤和潮土中微生物呼吸强度的影响以及对潮土氮转化的影响。结果表明:将供试农药以田间推荐剂量、10倍推荐剂量和100倍推荐剂量施入土壤15 d后，甲嘧磺隆对棕壤微生物表现为呼吸强度抑制作用，对潮土为促进作用，而红壤中除10倍推荐剂量处理组表现出抑制作用外其余两组均表现出促进作用；炔草酯会抑制红壤和棕壤中微生物的呼吸强度，但会促进潮土中微生物的呼吸强度。氮转化试验结果表明:以田间推荐剂量和5倍推荐剂量施入潮土后，甲嘧磺隆在7、14、28、42、56和70 d均能显著促进其硝酸盐含量；炔草酯除28 d时田间推荐剂量处理组的硝酸盐含量显著高于对照组外，其余0、7、14和42 d硝酸盐含量与对照组相比均无显著差异。综上所述，两种除草剂对3种土壤类型微生物的呼吸强度为低毒，对潮土氮转化功能没有长期影响。

Effects of sulformeturon methyl and clodinafop-propargyl on respiration intensity and nitrogen transformations of soil microorganisms

In order to explore the toxicity of hebicides on soil microorganisms, the nitrogen transformation of microorganisms in fluvo-aquic soil and the respiration intensity of microorganisms in krasnozem, brown soil and fluvo-aquic soil were determined after exposure to sulfometuron methyl and clodinafop-propargyl, respectively. The soils were treated with these herbicides at the recommended field concentration (RFC), 10 and 100-fold of RFC and then incubated for 15 days. In terms of sulfometuron methyl, the inhibition of respiration was abserved in the exposed brown soil, whereas soil respiration intensity was significantly increased in fluvo-aquic soil. In krasnozem, soil respiration was inhibited after the exposure to sulfometuron methyl in 10 fold application rate treatment, but it was stimulated in the other two treatments. With regards of clodinafop-propargyl, the results indicated that respiration were inhibited in krasnozem and brown soils, but it was stimulated in fluvo-aquic soil. Regarding to nitrogen transformation, sulfometuron methyl significantly increased the NO₃^--N contents of the fluvo-aquic soil after the exposure to the recommended field concentration (RFC) and 5-fold of RFC for 7, 14, 28, 42, 56 and 70 d, respectively. The NO₃^--N contents was significantly increased 28 d after the exposure to clodinafop-propargy. However, no significant change between the control and the treatment group was observed 0, 7, 14 and 42d after the exposure. In summary, sulfometuron methyl and clodinafop-propargyl showed low toxicity to soil respiration intensity in the three soils, and no long-term effects on nitrogen transformation were observed in the fluvo-aquic soil.