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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Water Management Research » Research » Publications at this Location » Publication #308014
Title: Effects of CO2 dissolution on phase distribution and degradation of dimethyl disulfide in soils under grape production

Author
item CONKLE, JEREMY - University Of California
item CABRERA, ALFONSO - University Of California
item THOMAS, JOHN - University Of Florida
item Wang, Dong
item GAN, JAY - University Of California

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2015
Publication Date: 4/13/2015
Citation: Conkle, J., Cabrera, A., Thomas, J., Wang, D., Gan, J. 2015. Effects of CO2 dissolution on phase distribution and degradation of dimethyl disulfide in soils under grape production. Pest Management Science. doi: 10.1002/ps.4004.

Interpretive Summary: Soil fumigation with chemicals other than methyl bromide has concerns with soil dispersion uniformity for achieving effective pest control. Dimethyl disulfide (DMDS) is a newly registered soil fumigant with good pest control efficacy but lack of dispersion in soils may limit its use. In a series of laboratory studies, CO2 was added in the DMDS for improved soil dispersion and measurements were made on its chemical-soil properties with the CO2 addition. While carbonation had a significant, but small effect on sorption to soil and negligible effect on the degradation of DMDS, it greatly increased DMDS’s Henry’s Law constant. The increased Kh should result in improved dispersion and distribution in subsurface treatments, especially in wet soils.

Technical Abstract: BACKGROUND: Dimethyl disulfide (DMDS) is a fumigant recently registered in parts of U.S. The fumigant has high pesticidal activity, but lower volatility compared to other fumigants, leading to less soil dispersion. This study assessed the use of CO2 as a propellant to improve soil dispersion and diffusion by evaluating the partitioning and degradation of DMDS after carbonation in four vineyard soils collected in California. RESULTS: The soil with the highest organic carbon content (Clarksburg) had highest soil-water partition coefficient (Kd) (p < 0.001), which increased after carbonation. However, DMDS sorption decreased in the Mecca and Fowler soils. The Henry’s law constant (Kh), which measures a compound’s potential for partitioning between air and water, doubled from 0.04 to 0.10 with the addition of CO2, indicating less DMDS solubility. Carbonation did not negatively affect DMDS’s half-lives in the different soils. CONCLUSION: While trials are needed for validation of field-scale impacts, carbonation had mixed effects on soil partitioning and no discernable impacts to degradation, but greatly decreased DMDS water solubility. This indicates that carbonation could improve some facets of the DMDS diffusion and dispersion depending on soil properties (carbon content and moisture) without greatly affecting its other behaviors.