Temperature and Moisture Effects on Fumigant Degradation in Soil

• Published in: Journal of environmental quality Vol. 28; no. 5; pp. 1436 - 1441
• Main Authors: Gan, J., Papiernik, S. K., Yates, S. R., Jury, W. A.
• Format: Journal Article
• Language: English
• Published: Madison, WI American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America 01-09-1999; Crop Science Society of America; American Society of Agronomy
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; fumigants; Fundamental and applied biological sciences. Psychology; Pollution; Pollution, environment geology; Soil and sediments pollution; Soil and water pollution; Soil degradation; Soil science; California; United States; North America; America; Biodegradation; Pollutant behavior; Soil moisture; Pesticides; Fumigant; Chemical degradation; Soil pollution; Medium effect; Organochlorine compounds; Chlorine Organic compounds; Organic isothiocyanate; Loamy sand soil; Sandy loam soil; Soil temperature
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq1999.00472425002800050007x

Recent discovery of the contribution of methyl bromide fumigation to stratospheric ozone depletion has revealed our limited understanding of the environmental processes of fumigants. For instance, little is known about fumigant degradation in soil under high temperature or low moisture conditions that prevail near the soil surface during fumigation. In this study we determined the interaction of soil temperature and moisture with degradation of 1,3‐dichloropropene (1,3‐D) and methyl isothiocyanate (MITC) for extended soil temperature and moisture ranges. Fumigant degradation increased 5 to 12 times when temperature increased from 20 to 50°C. It was further shown that chemical transformation of fumigants always increased with increasing temperature, but temperature effects on microbial degradation were fumigant dependent. The relative contribution of microbial degradation to the overall fumigant degradation was highest for the soil with highest organic matter content, and was greater for MITC than for 1,3‐D isomers. When the temperature was >30°C, microbial degradation of 1,3‐D was substantially suppressed, while that of MITC was greatly stimulated. As soil moisture content increased, 1,3‐D degradation accelerated, but that of MITC decreased. The specific responses of fumigant degradation to temperature and moisture variations should be considered when describing their transport in the environment, and also may be used for designing fumigation practices that allow reduced atmospheric emissions.