单甲脒农药对土壤微生物种群和土壤酶活性的影响

EFFECT OF MONOFORMAMIDINE PESTICIDE ON THE MICROBIAL POPULATION AND ENZYMATIC ACTIVITY IN SOIL

研究了单甲脒（Ｎ＇－２，４－二甲苯基－Ｎ－甲基甲脒，简称ＤＭＡ）对土壤微生物种群和土壤酶活性的影响．田间试验表明，喷洒单甲脒盐酸盐（ＤＭＡＨ）于棉花植株对土壤微生物种群和土壤酶活性无明显影响．实验室试验表明，投加ＤＭＡＨ于土壤对土壤微生物种群有不同的抑制作用；当ＤＭＡＨ在土壤中的浓度为２０ｍｇ／ｇ时，好氧异养菌总量开始降低，硝化细菌和放线菌、真菌的土壤ＤＭＡＨ抑制浓度分别为０．５ｍｇ／ｇ和０．１ｍｇ／ｇ．ＤＭＡＨ对土壤酶活性的影响亦不相同，脱氢酶对土壤中ＤＭＡＨ含量为１０ｍｇ／ｇ时其活性即有明显的减弱，而过氧化氨酶对ＤＭＡ的耐受性相当高，其活性的抑制浓度达５００ｍｇ／ｇ．试验还证明了土壤中ＤＭＡ的微生物降解作用．当ＤＭＡ在土壤中的浓度为５０～５００ｇ／ｇ时，其消解速率可从８．７５ｍｍ·ｋｇ－１·ｄ－１提高到４８ｍｇ·ｋｇ－１·ｄ－１．

Effect of monoformamiding(N-2, 4-dimdsylphenyl-N' -methylamidine, DMA)on the microbial population and enzymatic activity in soil was investbeted. The results obtained from field tests indicated that monoformamidine hydrochloride (DMAH)at various concentrations sprayed on cotton would not obviously affect soil microbial population. The laboratary tests of applying DMAH to soil showed that the soil microbial population would be inhibited to a different extent. Toeal counts of aerobic hetelotrophic bacteria decreased from 2. 3× 10￣8/g to 9×10￣7/g at the concentration Of 20 mg/g DMAH. DMAH at 0. 5 mg/g would inhibit nitrifying bacteria. Actinomyces and fungi were reduced at 0. 1 mg/g of DMAH. The effects of DMAH on soil enzymatic activity were abc different. Dehydrogenase was more susceptible to DMA than urease, shaccharase and phosphatase. Hydrogen peroxidase had relatively high tolerance to DMA and its activity was inhibited at 500 mg/g DMA in soil. Tests also demonstrated microbial degradation of DMA in soil. The velocity of degredating DMA in soil at 50～500 mg/g was increased from 8. 75 mg· kg￣(-1)· d￣(-1) to 48 mg· kg￣(-1)·d￣(-1).