Location: Contaminant Fate and Transport Research2011 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 effectiveness of using solar heat pulsing to sterilize soils in preparation for planting various specialty crops. The experimental design will include standard 40” raised beds and have a bare-soil control and three solarization treatments with three replicates. Soil temperatures and heat flux throughout the raised-bed will be measured for several weeks. Various meteorological measurements will be made to allow determination of the solar energy input to the experiment. Several plant pests will be placed in the beds, be subjected to solarization for 4-6 weeks and then assayed for survival. After the solarization period, the plots will be fumigated with approximately 40% and 70% of the standard rate of Telone Inline to determine if pest control improvement occurs. The experiment will also include a negative control (no solarization, no fumigation) and standard fumigation treatments. Once the data is available, a modeling study will be conducted to investigate the heat transport and fate and transport of fumigant chemicals in the soil beds.
3. Progress Report
Progress was made on all objectives, which fall under National Program 212, Component 1. Enable Improvements of Air Quality via Management and Mitigation of Emissions from Agricultural Operations. Research on this project focused on Problem Statement 1A: Understand, predict, and manage emissions from agricultural systems and relates to objective 1 of the parent project. A field-plot study was conducted to determine the combined effects of reduced-rate fumigation and soil solarization on the control of soil-borne pests under typical field conditions. Using a drip irrigation system, a reduced-rate (i.e., 70% or 40%) of Telone Inline (a mixture of 1, 3-dichloropropene and chloropicrin) was applied to raised soil beds and covered with standard high-density polyethylene film (HDPE), thermic film (Thermic), and a virtually impermeable film (VIF). The spatial and temporal variation in the soil fumigant concentration was measured to determine the concentration-time index, which is a measurement of exposure to the fumigant and can be related to the control of plant pests and diseases. The efficacy of pest control of various treatments was monitored using bioassay muslin bags containing soil infested with citrus nematodes (Tylenchulus semipenetrans). The results show that standard HDPE together with reduced-rate of Inline controlled more than 50% of nematodes. Compared to the standard HDPE treatment, soil solarization with Thermic and VIF films coupled with reduced-rate of Inline improved efficacy of parasitic nematodes in soils because of the synergetic effect of fumigant and enhanced soil temperature. Due to the low permeability of VIF, the greatest fumigant concentrations in soil were observed which led to nearly full control of nematodes in the soil. The information obtained from this study will be useful in developing new soil disinfestation methods that reduce reliance on fumigants and are more environmentally benign. During the course of this research project, progress was monitored throughout the year from regular individual and group meetings, phone conversations, laboratory visits and email correspondence.