Page Banner

United States Department of Agriculture

Agricultural Research Service


Location: Contaminant Fate and Transport Research

2009 Annual Report

1a. Objectives (from AD-416)
Conduct research to develop new and improved methods to manage pesticides and other organic agricultural chemicals to maintain healthy agricultural systems. Study the fate and transport of agricultural chemicals and investigate the effect of various soil and environmental processes that affect chemical movement in soil. Conduct research that provides "real-world" solutions to improve efficacy, reduce cost and foster a healthy environment. Develop new low-cost management approaches that minimize volatile emissions to the atmosphere, and transport to surface water and ground water.

1b. Approach (from AD-416)
An experimental site will be developed in Field 2B (UC-Riverside AgOps) to test the feasibility of using solar energy to sterilize soils in preparation for planting various specialty crops. A preliminary study will be conducted that consists of a bare-soil control and two solarization treatments. Soil temperatures throughout the raised-bed will be measured for several weeks. Various meteorological measurements will be made to allow determination of an energy balance for the experiment. Several plant pests will be selected and temperature-time mortality indices will be developed which will allow a determination of the potential effectiveness of each experimental treatment. The information obtained from the preliminary experiment will be used to determine if further experiments are warranted. Documents SCA with UC-Riverside.

3. Progress Report
Basic research was conducted to determine if Ca(OH)2, K2CO3 and NH3 could be used to decompose MeBr and reduce the emissions of MeBr from soil. Compared to a 7-15 day half-life in soil, ammonia was found to rapidly degrade MeBr (half-life was 2.5 hours) in a 1.0 M ammonia water solution. Even an ammonia concentration of 0.10 M reduced the half-life to 8.5 hours. An ammonia amendment in moist soil was also found to promote MeBr transformation. A concentrated ammonia solution was effective in degrading MeBr under plastic film. Apart from the portion that penetrated through the plastic film, nearly all of the MeBr was transformed in a short time. Using a virtually permeable film, (i.e., Hytibar), over 99.5% of the MeBr was destroyed by an ammonia-water solution in 8 hours. Based on these results, a new management practice could be developed for using MeBr as a soil fumigant without significant emissions. Research progress was monitored throughout the year from regular individual and group meetings, phone conversations, laboratory visits and email correspondence.

4. Accomplishments

Last Modified: 2/23/2016
Footer Content Back to Top of Page