为了解2，4-D对土壤微生物生态特征效应。通过盆栽试验，采用三因素完全随机设计，平板菌落计数法对不同时间土样进行土壤细菌、放线菌、真菌数量的测定。研究了2，4-D胁迫下添加尿素、多效唑对土壤微生物的影响，揭示了土壤细菌、放线菌、真菌在2，4-D胁迫下添加尿素、多效唑的动态变化。结果表明，高浓度2，4-D胁迫下，1～60d明显抑制了细菌的生长，对放线菌、真菌的生长呈先刺激后抑制的作用，直到第60天3种菌均未恢复到对照水平；低浓度2，4-D胁迫下，1～60 d对细菌、放线菌、真菌均呈抑制效应。添加尿素、多效唑刺激了土壤细菌、放线菌、真菌的繁殖，2，4-D+尿素、2，4-D+尿素+多效唑2种处理对3种菌的刺激效应更为显著，与对照相比，对细菌和放线菌的刺激效应极显著，在1～60 d平均最高激活率达396．5%和125．9%。

This experiment was carried out in pot culture test,by using three-factor completely randomized design and plate culture count to measure the number of soil bacteria,actinomyces and fungus sampled at different time.This research studied the influences when adding carbamide and under 2,4-D stress on soil microbes,which revealed the dynamic changes of soil bacteria,actinomyces and fungus when adding carbamide and under 2,4-D stress.The results showed that significant inhabitation to growth of soil bacteria were found from one to sixty days under high-concentration 2,4-D stress,but for actinomyces and fungus stimulation at first then inhibition later,three bacteria didn′t recovery to the level of control until 60th day;However,under low-concentration 2,4-D stress,inhibiting effects appeared to all these three bacteria from 1 to 60 days.So it is concluded that adding carbamide and could stimulate the reproduction of bacteria,actinomyces and fungus,and stimulating effects to the three bacteria of mixed 2,4-D and carbamide or mixed 2,4-D and carbamide and were more significant,Compared with the control,the stimulating effects to bacteria and actinomyces were significant at 0.01 level,the average highest activation rate reached 396.5 percent and 125.9 percent from 1 to 60 days.