1a. Objectives (from AD-416)
The Natural Resources Conservation Service (NRCS) and the Agricultural Research Service (ARS) have agreed to work together, as part of the national Conservation Effects Assessment Project (CEAP) initiative to quantify the environmental benefits of conservation practices at the watershed scale. The project plan detailed in this document represents one of 12 ARS CEAP watersheds established under the national CEAP initiative to address conservation and environmental research issues. Objectives of the project are to: 1) develop and implement a data system to organize, document, manipulate, and compile water, soil, management, and socio-economic data for assessment of conservation practices at field, farm, and watershed scales for the Mark Twain Lake watershed; 2) measure and quantify water quality, water quantity, and soil quality effects of conservation practices at the field, farm, and sub-watershed scale for the Mark Twain Lake; and 3) validate models, quantify uncertainties in model output, and conduct analyses with hydrologic models at field, farm, and watershed scales, and develop methodologies and decision support tools for application on watersheds within the Mark Twain Lake watershed.
1b. Approach (from AD-416)
This research will focus on developing tools and techniques to quantify the impact of implementing conservation practices within a watershed in the most economically efficient manner to achieve sustainable and targeted reductions of nutrients, sediment, herbicide, and pathogen loadings to the Salt River/Mark Twain Lake basin. The research encompasses the following approaches: 1) participation in the development of the STEWARDS database; 2) conduct water quality monitoring to characterize the hydrologic balance and nutrient/chemical loading to Mark Twain Lake; 3) conduct studies at field and plot scales to determine the effectiveness of various conservation practices and cropping systems to reduce nutrient, sediment, and herbicide transport; 4) develop a real-time PCR (RT-RCR) method for quantitation of pathogenic water-borne bacterial species; 5) use the SWAT model to evaluate conservation practices and conservation systems abilities to reduce nutrient, sediment, pesticide, and pathogen loadings in agricultural watersheds; and 6) apply the SWAT model to improve surface water quality assessment and planning.
3. Progress Report
In 2007, cooperation between ARS and Missouri Corn Growers Association staff facilitated efficient springtime re-installation of the monitoring network (automated samplers are removed in the winter months to prevent equipment damage), which was in place by early April 2007. Meetings between ARS and Midwest Environmental Consultants (MEC) laboratory and field staff occurred periodically over the last year to review sample collection and analysis procedures, hydrologic data, and improve field operations. Review of quality control samples by ARS technicians revealed problems with the quality of data received from MEC. Subsequent discussions with MEC staff revealed additional data quality problems for nutrient analyses, and a mutually agreed upon decision was made to have ARS conduct all future nutrient and sediment analyses in support of CEAP. Over the last year, the CSWQRU Water Quality Lab conducted herbicide analyses for 512 CEAP samples and 164 SIP samples. Other CEAP activities involved cross-location and collaborative projects related to rapid geomorphic assessments for three CEAP watersheds, initial soil and sediment collection in Goodwater Creek to determine sources of sediment (overland versus streambank), and a third study is being initiated to measure streambank erosion as a function of stream order and adjacent land use in two watersheds. The streambank erosion project has also facilitated positive relationships with about 20 landowners within the study area. The PAS work has been continued under this CRIS, with three years of field data collected. The APEX simulations should provide the necessary comparisons of productivity and environmental quality between the conventional and the precision agriculture systems. The Bonne Femme watershed U.S. EPA 319 Nonpoint Source Pollution Control grant disbursed cost-share funds for several projects related to streambank stabilization, on-site sewer upgrades, use of pervious pavement for a parking lot, and wetland restoration. The Stakeholder Committee completed the watershed plan in February 2007. To date, the plan has received strong support among the local governmental entities within the watershed (i.e., Boone County and the Cities of Ashland and Columbia). It has been approved by the Boone County Planning and Zoning Committee (which sends the plan to the County Commission for approval), the City of Ashland, and it has received verbal, but not formal, approval from the Columbia City Council. Additional education and outreach included a low impact development workshop for local developers, a debate on the economics of development, an on-site sewer BMP tour, the annual open house, and two newsletters sent to all landowners in the watershed.
Reaction of Chlorine and Isoxaflutole (Balance). When herbicides are present in untreated water, they can react with the chlorine used by water treatment plants for disinfection. In this research, scientists with the Cropping Systems and Water Quality Research Unit and the University of Missouri studied the breakdown of DKN, the herbicidal metabolite of the corn herbicide isoxaflutole (Balance), by chlorine. DKN has been shown to be present in surface waters of the major corn-growing states, and it has also been shown to rapidly react with chlorine. Our results showed that DKN will be completely broken down by chlorine during the water treatment process, but two potentially harmful products will be formed: cyclopropanecarboxylic acid (CPCA) and dichloroacetonitrile (DCAN). However, it appears that the levels of CPCA and DCAN formed will be below those reported to cause toxic effects to humans or animals. This research benefits the general public by identifying two potentially harmful products and showing that they were present at sub-toxic levels and that DKN will not be present in drinking water supplies that use chlorination. NP201: Problem Area 6, Water Quality Protection Systems; 6. New knowledge and prediction capabilities of the physical, chemical, and biological processes affecting the retention, transformation, and transport of pesticides. Vegetative Buffers Reduce Nutrients in Soil and Groundwater Effective vegetative buffers require grass species that can capture nutrients before they run off the surface or leach to groundwater. Scientists with the Cropping Systems and Water Quality Research Unit and the University of Missouri conducted a field study at the University of Missouri’s Horticulture and Agroforestry Center using five grass treatments (orchardgrass, tall fescue, smooth bromegrass, timothy, and switchgrass) plus a bare ground control treatment to evaluate the ability of the grasses to scrub nutrients from soils and prevent their transport to shallow groundwater. All grass species, except timothy, reduced nitrate concentrations in shallow groundwater by ~99% compared to the control, and switchgrass also reduced phosphate leaching by 60 to 74% compared to the control. In addition, grass treatments reduced soil nitrate levels by 41 to 91% below that of the control. Overall, switchgrass, smooth bromegrass, and tall fescue were the most suitable for use in vegetative buffers because of their superior ability to reduce soil nitrate and nutrient leaching. NP201: Problem Area 6, Water Quality Protection Systems; 1. Scientific information regarding nutrient retention, transformation and transport processes, and field management techniques that reduce off-site nutrient movement. Development of New Analytical Methods for Herbicides and Their Metabolites in Soils and Plants Sensitive analytical methods are needed to accurately assess the environmental fate of herbicides and their metabolites. In collaboration with University of Missouri scientists, two new analytical methods were developed: one for the analysis of atrazine and its chlorinated metabolites in plants; and the other for the analysis of isoxaflutole (IXF) and its two primary metabolites in soils and plants. Both methods employ chromatography, to separate the compounds of interest, with mass spectrometry for detection, resulting in sub-part per billion detection limits and 1 to 2 orders of magnitude better sensitivity than previously published methods. The methods were applied to measurements of plants or soils from a field experiment to demonstrate their utility. In forage grasses, the results revealed that the ratio of metabolites to parent compound were good indicators of the detoxification pathways and overall sensitivity to each herbicide. Scientists, regulators, and industry will benefit from these methods since appropriately sensitive methods are now available for measuring these herbicides and their metabolites in the environment, which will facilitate an improved understanding of their environmental fate and lead to the implementation of vegetative buffers that more effectively prevent contamination of surface and ground waters. NP201: Problem Area 6, Water Quality Protection Systems; 6. New knowledge and prediction capabilities of the physical, chemical, and biological processes affecting the retention, transformation, and transport of pesticides.
5. Significant Activities that Support Special Target Populations
Lerch, R.N., Lin, C.H., Leigh, N.D. 2007. Reaction Pathways of the Diketonitrile Degradate of Isoxaflutole with Hypochlorite in Water. Journal of Agricultural and Food Chemistry. 55(5):1893-1899.