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United States Department of Agriculture

Agricultural Research Service


Location: Cropping Systems and Water Quality Research

2008 Annual Report

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 2008, cooperation between ARS and Environmental Resources Coalition (ERC is a subsidiary of the Missouri Corn Growers Association) staff facilitated efficient springtime re-installation of the Salt River monitoring network, which was in place by early April 2008. In collaboration with ERC, two new field studies were initiated, both dealing with remediating water from Parallel Terrace Outlets (PTO). One study utilizes grass buffers and the other wetlands. In both cases, water discharging from PTOs is split evenly between treatments. Treatments for the grass buffer study include tall fescue and reed canarygrass. The wetland study has three wetlands differing in the area ratio between the drainage area and the wetland area: 50:1; 100:1; and 150:1. Over the last year, the CSWQRU Water Quality Lab received 1,115 Conservation Effects Assessment Project samples and 149 PTO samples for nutrient, herbicide, and sediment analyses. Other CEAP activities in 2008 involved the establishment of a streambank erosion project at 31 sites located in Crooked and Otter Creek watersheds (both watersheds are located within the Salt River Basin). Treatments include stream order (1st through 3rd) and adjacent land use (cropped, riparian forest, forest, and pasture). The project has also facilitated positive relationships with about 15 landowners within the study area. Another CEAP-related activity involves the application and validation of a risk assessment tool for vulnerability to pesticide transport. Two contrasting watersheds (Youngs Creek, a claypan watershed; and Bonne Femme Creek, a karst watershed) have been chosen for study. The risk assessment tool will be run for various scenarios to determine vulnerability of different herbicides to losses by leaching, solution runoff, and particle-adsorbed runoff. In addition, the Missouri CEAP was one of only six locations to upload watershed data to STEWARDS in 2008. Lastly, an overview paper of the Missouri CEAP will be included in the CEAP special issue of the Journal of Soil and Water Conservation in the November/December 2008 issue. The precision agriculture system work has been continued under this project, with four years of field data collected. Considerable effort has been devoted this year to the calibration and validation of APEX. The APEX model was calibrated and validated for flow and atrazine based on the corn years’ plots data. A sensitivity analysis of the shape of the hillslope and of the length of the footslope on flow and atrazine load was conducted. The validated APEX model will 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 completed its final year. The Stakeholder Committee completed the watershed plan in February 2007. This year the plan was adopted unanimously by the three major local governmental entities within the watershed: the Boone County Commission, the City Council of Columbia, and the Board of Alderman of Ashland. Boone County staff are currently drafting ordinances recommended by the watershed plan. NP 211, comp 1.

4. Accomplishments
1. Vegetative Buffers Reduce Atrazine in Soil and Groundwater A sound multi-species vegetation buffer design should incorporate grass species that facilitate rapid degradation and sequestration of deposited herbicides in the buffer. A field lysimeter study with five forage species was established to assess their ability to enhance atrazine dissipation in the environment via plant uptake and degradation and detoxification in the rhizosphere. Results suggested that the majority of the applied atrazine remained in the soil and only a relatively small fraction of herbicide leached to shallow groundwater (<15%) or was taken up by plants (<4%). The grasses enhanced atrazine degradation in soil through their ability to increase microbial growth and activity in surface soil. Because of its ability to tolerate high levels of exposure to atrazine and the high degree of enhanced soil degradation, switchgrass is recommended for use in vegetative buffers designed to reduce atrazine transport to surface or ground waters. This research benefits conservation agencies, such as NRCS and state conservation departments, since it provides the needed science for improving vegetative buffer designs for improved protection of water resources impacted by row crop production. NP211, component 1: 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

Review Publications
Lin, C.H., Lerch, R.N., Garrett, H.E., George, M.F. 2008. Bioremediation of Atrazine-Contaminated Soil by Forage Grasses: Transformation, Uptake, and Detoxification. Journal of Environmental Quality. 37:196-206.

Last Modified: 2/23/2016
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