二甲基二硫的生物活性评价及对土壤养分的影响

采用室内生物活性测定方法,评价二甲基二硫(dimethyl disulfide,DMDS)对土壤病原线虫和土传病原菌的毒力,比较不同浓度药剂处理对土壤理化性质和土壤呼吸的影响,为探究DMDS作为新型土壤熏蒸剂提供切实可行性的依据。结果表明:DMDS熏蒸对土传病原线虫和镰刀菌属的LD_(50)分别为4.743 mg/kg和1.513 mg/kg,可见DMDS对病原线虫和镰刀菌有良好的生物活性。对土壤理化性质进行数据分析发现:DMDS能显著增加土壤铵态氮含量,抑制硝化作用过程,减少NO~-_3-N的产生,提高植物可吸收态氮素水平。DMDS处理的土壤有机质含量和电导率均显著高于对照土壤,而土壤pH和速效钾含量较对照均有降低。此外,熏蒸土壤中有效磷含量较对照减少,但两者无显著差异。对DMDS熏蒸后土壤进行底物诱导呼吸试验,表明DMDS能够在试验初期抑制土壤微生物生物量。本试验结果可为指导DMDS的科学使用提供理论依据及对土壤微生物活性的影响作出科学评价。

Biological activity of dimethyl disulfide and its effects on soil nutrients

The toxicity of dimethyl disulfide (DMDS) to soil nematodes and soil borne pathogens were evaluated by laboratory bioassay, and the effects of different concentrations of DMDS on soil physical and chemical properties and soil respiration were compared in order to explore the feasibility of DMDS as a new soil fumigation agent. The results showed that the LD50 of DMDS against soil borne nematodes and Fusarium spp. were 4.743 mg/kg and 1.513 mg/kg, respectively, showing that DMDS had a good biological activity to nematodes and Fusarium spp. Soil physical and chemical property data indicated that DMDS could significantly increase soil ammonia nitrogen content, inhibit nitrification process, reduce the production of nitrate nitrogen, and improve the level of plant absorbable nitrogen. The contents of organic matter and electrical conductivity in the soil treated with DMDS were significantly higher than those in the control soil. The pH and available potassium content of the soil treated with fumigant were lower than those of the control. In addition, the available phosphorus content in fumigated soil was lower than that in the control, but there was no significant difference between DMDS treatments and the control. The substrate induced respiration test of DMDS fumigation indicated that DMDS could inhibit soil microbial biomass in the early stage of the experiment. These results can provide a theoretical basis for guiding the scientific application of DMDS and making a scientific evaluation of the effect on soil microbial activity.