Location: Soil and Water Management Research2008 Annual Report
1a. Objectives (from AD-416)
1. Integrate knowledge of retention, transformation, and transport of agrochemicals, including newer pesticides and veterinary pharmaceuticals, in soil and water, to facilitate selection and validation of management practices at the field to landscape scale that minimize potential offsite transport to surface and ground waters. 2. Identify practices that protect water quality and conserve soil resources in emerging farming systems of the North Central U.S. 3. Quantify the impact of agricultural drainage management systems on net greenhouse gas emissions and pesticide leaching losses. 4. Quantify the environmental impact of Best Management Practices on water quality in turf systems.
1b. Approach (from AD-416)
Results from research on factors affecting possible offsite transport of agrochemicals (nutrients, pesticides, and veterinary chemicals) to surface and ground waters, conducted on multiple scales (laboratory, field plots, and mini-watersheds) in an interdisciplinary manner, will be used to develop management practices that are relevant to protecting surface and ground waters in the North Central United States. Research will be conducted in interconnected experiments on basic processes affecting agrochemicals, spatial and temporal variation of processes, and impacts of management practices on environmental fate of agrochemicals. For instance, basic research on fate of pesticides and veterinary pharmaceuticals will be conducted in the laboratory on soils from selected field plots and watersheds to obtain basic information on processes. This information will be used in turn to help explain results of management practice effects on fate of agrochemical in fields and small watersheds. Management practices to be studied include: new cropping systems associated with large dairy operations; farming systems providing carbon sources for ethanol production; agricultural drainage management systems; and turf management systems. We will obtain information on the spatial and temporal variability of the processes and an assessment of the impact of altering the agronomic management practices on off-site transport of pesticides and fertilizers from non-agricultural, i.e. turf, and agricultural systems. Information obtained will include: an assessment of the predictive ability of transport models to simulate runoff and estimate chemical loading to surface and ground waters; identification of management practices that protect water quality and conserve soil resources in emerging farming systems in North Central U.S; and redefined agricultural systems models that can predict the impact of management of agricultural drainage systems on net greenhouse gas emissions in tile drained fields under the different climate and soil conditions of the Midwest corn belt.
3. Progress Report
Obj. 1 Progress: Effects of addition of olive oil production waste, alperujo, on sorption and mineralization of terbuthylazine and atrazine, herbicides widely used in olive tree cultures were determined in freshly treated and aged soils, which were either unamended or amended with alperujo. Changes in sorption/availability of nicosulfuron with aging in different soils from the midwest US, Hawaii, and Brazil were determined in laboratory studies. Over 1500 soil cores from corn and soybean plots managed with conventional, conservation, strip or no tillage were collected for analysis. Over 1200 soil samples were analyzed for herbicide residues, and over 300 water samples were analyzed for pesticide, nutrient, and bromide tracer concentrations. Obj 2 Progress: On farm, corn silage production with and without a rye cover crop was compared on adjacent 60 ha fields. Rye was planted after silage harvest in the fall of 2007 and was killed prior to corn planting in 2008. The effect of the rye on subsurface drainage volume, nutrient and sediment loss thorough subsurface drainage, and soil nutrient status was measured. At the plot scale, four treatments were compared: corn planted in early May, corn planted in mid May, corn planted in mid May after early rye harvest, and corn planted in early June after late rye harvest. Evapotranspiration (ET) modeling and time domain reflectometry profile water storage measurements were used to compare the water balance for the living mulch system and for conventional corn production. Modeling was based on the FAO-56 method modified for a living mulch cropping system. Obj. 3 Progress. Gas-flux chamber anchors were installed at the Hicks Farm in spring 2007 and again in spring 2008 for measuring soil-to-atmosphere fluxes of nitrous oxide and methane. Gas fluxes were measured on 22 sampling dates during the 2007 growing season. Sampling at a similar frequency has occurred to date during the 2008 season. Obj. 4 Progress. Implemented new management strategies on fairway turf plots; instrumented turf plots with new flow meters; collected 300 rainfall runoff samples, 300 snow melt runoff samples and 175 turf/soil cores from fairway turf plots. Progress relates to NP211 as follows: Obj. 1: Problem Area 6 (Water Quality Protection Systems), Product 6, New knowledge and prediction capabilities of the physical, chemical, and biological processes affecting the retention, transformation, and transport of pesticides. Obj. 2: Problem Area 6, Product 1, Scientific information regarding the retention, transformation, and transport of nutrients, and management applications that reduce off-site nutrient movement; Obj 3. Problem Area 3 (Drainage Water Management Systems), Product 1, Guidelines for improved agronomic, nutrient, and pesticide management practices to be used in combination with adoption of drainage water management; 4: Problem Area 5 (Watershed Management, Water Availability, and Ecosystem Restoration), Product 1, Best management practices, assessment tools, and decsion support systems for managing water quantity and quality.
1. Accompishment 1: Mineralization of the Bacillus thuringiensis Cry1Ac endotoxin in soil. Research has shown that genetically modified crops can exude insecticidal chemicals (Bt Cry toxins) from roots into the soil or release the toxins through decomposition of crop residues. In recent years, concerns dealing with the impact of Cry toxins on the soil ecosystem have been expressed in public and scientific debate, but have not yet been adequately addressed. Results from the present study clearly illustrate that the Bt toxin is degraded by the soil microbial community and does not persist within the soil as has been previously reported by other researchers. Our results clearly illustrate the fact that the Bt toxin eventually released into the soil by incorporation of plant residues and/or root exudation of GM crops is actively degraded by the soil microbial community rather than persisting for several months. This study demonstrates that there would be no risk of bioaccumulation of the Cry1Ac toxin in soil eventually released by Bt-protected crops and that producers can safely use these crops. Accomplishment 1 addresses NP 211, Problem Area 6 (Water Quality Protection Systems), Product 6, New knowledge and prediction capabilities of the physical, chemical, and biological processes affecting the retention, transformation, and transport of pesticides, pathogens, pharmaceuticals and other contaminants and new management practices and tools for reducing their offsite movement, Subproduct 6.1, Data sets describing the loss pathways of agricultural chemicals including transformation, leaching, runoff and gaseous emissions of agricultural pollutants as a function of management practice.
2. Accomplishment 2. Evaluation of vegetable production management practices to reduce the ecological risk of pesticides. The detection of pesticides in surface waters and their reported negative impacts to non-target organisms has resulted in public concern. We evaluated the ability of agricultural management practices to reduce pesticide transport with runoff and associated ecological risks. Measured pesticide concentrations in edge-of-field runoff, calculated environmental concentrations of pesticides in receiving surface waters, and risk assessment of pesticides to aquatic organisms in the receiving waters demonstrated that changes in mulching practices in vegetable production will reduce concentrations of pesticides in tributaries to levels below median lethal concentrations and below U.S. EPA guidelines to protect aquatic life. This research will benefit both agricultural producers and the environment as understanding processes that control the environmental fate of pesticides, their exposure and risk to non-target species, and identifying management practices that reduce the off-site transport of pesticides will increase pesticide efficacy at sites of application while reducing pesticide concentrations in surrounding surface waters; thereby minimizing exposure and adverse impacts to non-target aquatic organisms. Also, this study demonstrates the need to consider the management practice when assessing the potential risks for certain pesticides. Accomplishment 2 addresses NP211, Problem Area 6 (Water Quality Protection Systems), Product 6, New knowledge and prediction capabilities of the physical, chemical, and biological processes affecting the retention, transformation, and transport of pesticides, pathogens, pharmaceuticals and other contaminants, Subproduct 6.2, Scientific information regarding the retention, life cycles, and transport of pesticides, pharmaceuticals, and other contaminants and management applications that demonstrably reduce off-site movement.
Koskinen, W.C., Ochsner, T.E., Stephens, B.M., Kookana, R.S. 2006. Sorption of isoxaflutole diketonitrile degradate (DKN) and dicamba sorption in unsaturated soil. Journal of Environmental Science and Health. 41:1071-1083.