| The wide use of herbicides courses a risk of pollution of the subsoil and consequently contamination of water resources. Atrazine and metsulfuron-methyl are two kinds of herbicides that have been popular used in China.Their physico-chemical and biological behaviors have been evaluated by many researches. However, few researches on effect of addition of organic amendments and fertilizers on microbial biomass and herbicides degradation in soils have been conducted. We took atrazine and metsulfuron-methyl as examples to evaluate their dynamics of degradation in soils and the responses of microbial biomass after application of organic matters and fertilizers. The objectives are to find out the relationship among of organic matters/fertilizers added,, microbial biomass and herbicides degradation, and for remediation of soils contaminated by herbicides. The main results were summarized as follows:Effect of organic matters and fertilizers on microbial biomass in soils contaminated by atrazine/metsulfuron-niethyl herbicides(l)The contents of soil microbial biomass C, N and P significantly decreased after application of atrazine at the rate of 22. 5kg ha-1. Compared with control, microbial biomass C, N and P in soils treated with atrazine were decreased by 13. 51%, 10.12% and 11. 05% in paddy field on desalting muddy polder, respectively; 7. 35%, 6. 01% and 10. 81% in blue clayed paddy, respectively; 7. 30%, 9. 75% in paddy field on quaternary red clay(nodetermination the microbiai biomass phosphorus), respectively. The contents of soil microbiai biomass C, N and P also significantly decreased after application of metsulfuron-methyl at the rate of 22. 5kg ha-1. Microbiai biomass C, N and P in soils treated with metsulfuron-methyl were decreased 12. 37%, 11. 79% and 11. 94% in paddy field on desalting muddy polder, respectively; 10. 70%, 8.43% and 13. 66% in blue clayed paddy, respectively 8. 55%, 11. 95% in paddy field on quaternary red clay(no determination the microbiai biomass phosphorus), respectively.(2)In all three soils contaminated by both atrazine and metsulfuron-methyl, the contents . of microbiai biomass C, N, P increased after addition of organic matters and fertilizers. The higher microbiai biomass was found in treatments with organic matters than that with fertilizers. Among three organic matters added, content of micromial biomass followed the order of decomposed pig manure > Chinese clover > rice straw. The higher application of organic matters coursed the more contents of microbiai biomass. Among fertilizers, contents of microbiai biomass followed the order of N+P>N>P. This suggested that application of organic amendments and fertilizers can reduce the toxicity of atrazine and metsulfuorn-methyl to soil microorganisms, and improved the activities of microorganisms to degrade herbicides.(3)After oraganic amendments and fertilizers were added to the atrazine-contaminated soils, microbiai biomass C in paddy field on desalting muddy polder; blue clayed paddy and paddy field on quaternary red clay increased by 2. 59-130. 61%, 7. 93-71. 59% and 3. 39-105. 65%, respectively. Microbiai biomass N in corresponding soils by 4.26?88.11%, 6. 39-62. 62% and 9. 65-95.10% respectively, and microbiai biomass P by 12. 40-175. 77% and 3. 67-154. 02%(no determinate in paddy field on quaternary red clay), respectively.After organic amendments and fertilizers were added to the metsulfuron-methyl-contaminated soils, microbiai biomass C increased by 0.23-113.14% in paddy field on desalting muddy polder, 0.30-46.48% in blue clayed paddy, and 1.82-83.76%in paddy field on quaternary red clay, respectively, Microbiai biomass N in correspoading soils by 4.27-67.87%, 5.43-58.36% and 5.05-95.40%, respectively, and microbiai biomass P by 6.03-139.59% 4.09-141.26% (no determinate in paddy field on quaternary red clay), respectively.(4)In three atrazine-contaminated soils, the dynamic responses of the microbiai biomassC, N and P with incubation times were similar after application of organic matters and...
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