ARS | Publication request: REMEDIATION OF FUMIGANT COMPOUNDS IN THE ROOT ZONE BY SUBSURFACE APPLICATION OF AMMONIUM THIOSULFATE

Submitted to: American Chemical Society National Meeting
Publication Type: Proceedings/Symposium
Publication Acceptance Date: August 22, 2002
Publication Date: August 22, 2002
Citation: Papiernik, S.K., Ernst, F.F., Dungan, R.S., Zheng, W., Guo, M., Yates, S.R. 2002. Remediation of fumigant compounds in the root zone by subsurface application of ammonium thiosulfate. 224th American Chemical Society National Meeting. Boston, MA. Aug. 18-22, 2002. Paper No. 55

Technical Abstract: Fumigants are widely used to control soil-borne pests, such as nematodes, fungi, and weeds in soils to be planted to high-cash-value crops. Emissions-reduction strategies are required to minimize air contamination by fumigants and to increase efficacy. In some current soil fumigation practices, the fumigant is applied with water through subsurface drip irrigation lines. In these experiments, we investigated the potential for subsurface application of ammonium thiosulfate (ATS) to reduce soil concentrations of fumigants following soil application, thus reducing the threat of groundwater contamination and potential phytotoxic effects on the crop. Soil gas samples collected prior to ATS application indicated that significant concentrations of halogenated fumigants remained in the root zone following a 10-day fumigation period. Halogenated fumigant concentrations in the root zone were depleted ~5 times more rapidly in ATS-treated mesocosms than in mesocosms receiving only water. Because the fumigant MITC is not affected by ATS application (no chemical reaction occurs between MITC and ATS), MITC was dissipated in ATS-treated and non-treated mesocosms at approximately the same rate. These results indicate that for situations in which residual concentrations of halogenated chemicals are present in the soil, subsurface application of nucleophilic compounds such as ATS may be valuable for reducing the threat of leaching, runoff, and phytotoxicity to crops.