Effects of soil type, temperature, moisture, application dose, fertilizer, and organic amendments on chemical properties and biodegradation of dimethyl disulfide in soil

Dimethyl disulfide (DMDS) is a potential alternative to methyl bromide for soil fumigation to control soil- borne disease. Laboratory experiments were conducted to investigate the effects of combinations of soil and environmental factors of DMDS degradation in soil. The results showed that soil pH and soil organic matter content are the major factors influencing the degradation of DMDS in soil. Generally, DMDS degradation was significantly slower in acidic and high organic content soils. The degradation rate increased with temperature and water content. However, when the temperature exceeded 35 degrees C, the degradation rate decreased, and when the soil water content was raised to 10%, the change in DMDS degradation was not significant in Fangshan soil. The degradation of DMDS in soil depended on the initial application rate. Degradation slowed down as the fumigant application rate increased. DMDS degradation in soil was restrained by the addition of organic matter to soil, and the effect was enhanced by increased dosage. DMDS degradation in soil was also restrained by the use of chemical fertilizers except when amended with sodium dihydrogen phosphate and sodium thiosulfate. The impact of fumigant application rates and chemical fertilizers on bacterial communities in soil was determined by 16S rRNA amplicon sequencing. The results showed that bacterial diversity was affected by different treatments. Our study provides useful information to evaluate environmental safety assessments of DMDS in soil.