Project Number: 3622-12130-004-02
Project Type: Specific Cooperative Agreement

Start Date: May 23, 2005
End Date: Apr 30, 2009

Objective:
The objectives of this cooperative research project are: 1. To measure environmental impacts of Best Management Practices (BMPs) for reducing corn herbicide and nutrient transport associated with parallel terrace outlets. Measurements will include edge-of-field pesticide, nutrient, and sediment concentrations and flow at two field studies established by ERC. 2. To measure concentrations of, and with stream flow, compute the transport of, sediment, nutrients (dissolved and total N and P), and pesticides (Atrazine and Metolachlor and metabolites) at 13 gauging stations surrounding Mark Twain Lake for the ARS Conservation Effects Assessment Project (CEAP). 3. To analyze and publish data from ERC¿s previous Watershed Research, Assessment and Stewardship Project (WRASP) and current SIP projects in appropriate peer-reviewed publications and other outlets. 4. To jointly analyze and publish data from the two parallel terrace outlet studies in appropriate peer-reviewed publications and other outlets.

Approach:
Field Studies Flow from an underground terrace outlet will be collected and distributed evenly over two vegetative filter strip treatments (tall fescue and reed canary grass) using water level control structure flow splitters. Runoff samples will be collected just above the flow splitter (upstream of the filter strips) and at the outlet of the two filter strips. A weir is used to measure flow coming from the cropped field and flumes are used to measure flow at the outlet to the filter strips. Contaminant analyses will include nutrients (dissolved and total N and P) and atrazine, DEA, and DIA. The study is located within the Crooked Creek watershed of the Salt River basin. A constructed wetland will be evaluated to demonstrate a potential BMP for reducing nutrient, sediment, and herbicide loadings into streams and reservoirs. The constructed wetland site is established within a small predominantly row-cropped watershed (approximately 23 acres in size) located in northwestern Missouri. The wetlands are designed to serve as a filter for nutrients, sediments, and herbicides. The wetland is divided into multiple wetland cells to demonstrate the effectiveness of different watershed/wetland size ratios. Weirs and automatic samplers are placed at the inflow and outflow points of the wetland cells to collect flow data, and equal flow interval composite samples will be collected during ~10 runoff events per year to estimate nutrient, sediment, and herbicide loadings into and out of the wetlands. Salt River Monitoring The CEAP monitoring of the Salt River basin focuses on the integrated effect of mixed land use for watershed-scale areas ranging in size from 28 to 2000 mi2. Automated samplers have been deployed at 12 sites within the basin. Grab samples are collected under low flow conditions and following runoff events at 13 sites (same 12 sites with autosamplers plus the outlet to Mark Twain Lake). Automated samplers capture equal flow interval composite samples during runoff events. Flow measurements are based on USGS rating curves or by establishment of rating curves by ARS and MEC personnel. Samples are analyzed for 5 herbicides and two atrazine metabolites, nutrients (dissolved and total N and P), and suspended sediment.