Edge-of-field monitoring: Discovery Farms

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The USGS is cooperating with Discovery Farms to understand agriculture’s impact on the environment and help producers find ways to minimize their impact while remaining economically viable. Edge-of-field or subsurface tile monitoring stations measure runoff-event volume, including snowmelt, and collect samples which are analyzed for suspended sediment, phosphorus, nitrogen, and chloride.

Photo of an edge-of-field surface site with monitoring components labeled

Typical monitoring station used to quantify surface-runoff volume and to collect samples of runoff from the field edges of small agricultural basins.


Agriculture has historically been cited as one of the primary causes of water-resource degradation, especially in Wisconsin. Nonetheless, agriculture plays a critical role in the way that we live, the food we eat, and the economics that drive our society. Wisconsin producers are facing difficult challenges to remain economically viable: new farm bills are threatening to take away subsidies, increasing fuel and fertilizer costs are limiting profitability, and legislation has been proposed that may significantly change the ways that producers have historically operated. In addition, producers are receiving increased pressure to be “environmentally friendly”: well contaminations, manure spills, and numerous recent fish kills have all been linked to agriculture. Agricultural production and the associated potential environmental hazards are being brought under public scrutiny perhaps more now than ever before.

The USGS is cooperating with the Discovery Farms program to collect data to help understand agriculture’s impact on the environment and work with producers to evaluate ways to minimize their impact, while at the same time assuring that the producers stay economically viable.



Monitoring stations are installed throughout Wisconsin on selected Discovery Farms which represent diverse land characteristics, production schemes, and management styles. Monitoring stations are installed at sites in small, headwater streams, edges of fields, and in subsurface tiles. All monitoring stations are designed to continuously measure runoff volume and to collect discrete water samples during storm-runoff periods, including snowmelt. The discrete samples collected are combined into a single sample such that the sample represents the average concentration over the duration of the storm. These composite samples are analyzed for total phosphorus, dissolved reactive phosphorus, suspended sediment, total dissolved solids, ammonium- N, nitrate + nitrite - N, Kjeldahl - N, and chloride. Storm loads are computed based on the discharge information and constituent concentrations. 

One of the primary experimental approaches of the project is to conduct multiple paired-watershed analyses on each farm to determine the impacts of the current management practices. If the current production system is deemed to need modification, changes will be made to see if modification of these practices significantly reduces constituent yields. On-farm information including cropping rotations, residue checks, manure management, and financial records are collected by the Discovery Farms staff to help understand the production system and the impacts of management changes. Studies are expected to last between five and seven years on each farm. 

In addition to the paired-watershed design, several other investigations will be conducted on various aspects of the farms. These studies may include, but not be limited to: comparing constituent yields from each farm to those in other regions of Wisconsin, comparing constituent yields from one type of management system to that of a different management system, comparisons of measured sediment losses versus loss estimates from various predictive indices, development, calibration, and verification of a phosphorus-loss risk index, and development, calibration, and verification of a hydrologic and chemical model (surface and ground water).

Figure showing example hydrograph and water-quality samples collected during a runoff event

Example hydrograph (red line) and water-quality samples (green circles) showing the discharge response and potential variability in chemical concentrations of water samples collected during an edge-of-field runoff event. (Public domain)



(See the Publications tab above for official USGS publications.)

Minks, K.R., Ruark, M.D., Lowery, B., Madison F.W., Stuntebeck, T.D., Komiskey, M.J., Kraft, G.J., 2015, At-grade stabilization structure impact on surface water quality of an agricultural watershed: Journal of Environmental Management, 153:50-9

Radatz, T.F., Thompson, A.M., Madison, F.W., 2012, Soil Moisture and Rainfall Intensity Thresholds for Runoff Generation in Southwestern Wisconsin Agricultural Basins. Journal of Hydrological Processes, v. 27, i.5

Komiskey, M.J., Stuntebeck, T.D., Frame, D.R., and Madison, F.W., 2011, Nutrients and sediment in frozen-ground runoff from no-till fields receiving liquid-dairy and solid-beef manures: Journal of Soil and Water Conservation, v. 66