NESPAL > Water Use & Quality > Research Projects > Assess Impacts of Precision Ag BMP's

Assessing the Water Quality Impacts of Precision Farming Best Management Practices
by George Vellidis

During 1998, scientists from Georgia, Minnesota, Montana, and South Dakota formed a Consortium of Centers dedicated to site specific resource management (SSRM), also known as precision agriculture. The Consortium functions as a virtual learning laboratory, involving multi-disciplinary, multi-stakeholder teams from the major US commodity cropping systems. Leveraging these resources, the consortium is identifying information systems that facilitate more effective management of the unique conditions within fields. The four leading Consortium Centers are the University of Georgia's National Environmentally Sound Production Agriculture Laboratory (NESPAL), the University of Minnesota's Precision Agriculture Center; the Montana State University's Precision Land and Climate Evaluation Systems; and South Dakota State University's South Dakota's Precision Farming Initiative. USDA-ARS is also a key partner in this effort.

One of the Consortium's major objectives is to evaluate whether precision agricultural practices reduce runoff and leaching losses of fertilizer and herbicides to surface and ground waters. Beginning in the fall of 2000 a series of similar experiments on plot, field, and small watershed scales were initiated in each of the different regions represented by each member of the consortium to evaluate in a definitive manner the effect of precision applications of nitrogen and/or herbicides on surface and ground water quality. In Georgia, we are concentrating on the small watershed scale experiments. Detailed information about all the experiments can be obtained by downloading the PDF file highlighted below.

Small Watershed Scale Experiments
The experiments are taking place on 4 farms – 3 family-owned farms and a NESPAL farm. Within each farm, we have located a large center pivot-irrigated field that can be topographically divided into 2 small watersheds. On one of the 2 watersheds, precision agriculture Best Management Practices (BMPs) such as site-specific variable rate techniques are used to apply irrigation water, fertilizers, herbicides, and other agrochemicals. The second small watershed is treated with conventional uniform application of agrochemicals and irrigation water. Both watersheds are being studied over 2 complete cropping cycles to evaluate in a definitive manner, the effect of precision applications of water, nitrogen, animal manures and/or herbicides on surface and ground water quality.

The uniform rates are based on best management practices (timing and rate) identified for each region. Variable rates of water, nitrogen and herbicides are based on best management practices combined with information obtained from intensive soil sampling across each field used in conjunction with University fertilizer recommendation guidelines and labeled herbicide rates.

The watershed of each field was delineated and an appropriate water quality sampling device (h-flume at the watershed outlet, flow sensor and water quality sensor in a tile drain outlet, etc.) installed. If necessary, low earthen berms were constructed to divert surface flow to the flume. Because we are primarily interested in nutrient and herbicide loading differences between the two field-scale watersheds, the sampling regime consists of collecting weekly, composite, flow-proportional water samples of runoff events.

Funding: This work was supported by funds from the Georgia Department of Natural Resource - Environmental Protection Division's 319(h) Program, the USDA-CSREES Fund for Rural America Program, and by Hatch and State funds allocated to the Georgia Agricultural Experiment Stations.