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Home > Protecting Our Lands & Waters > Best Management Practices > Field Scale Drainage Water Quality Demonstrations

Field Scale Drainage Water Quality Demonstrations

Long term field scale evaluations are critical to “bridge the gap” and demonstrate that BMPs are effective at the field scale.

Limited information exists about tile drainage water quality and the impacts it has on the larger watershed. Two separate field scale water quality demonstration sites are currently in operation in southern-Minnesota to evaluate and demonstrate best management practices (BMP’s) and impacts to water quality both at the field scale and the larger watershed.

Minnesota farmers play an important role in finding solutions to water quality concerns and need to be assured that nutrient and pesticide Best Management Practices (BMP’s) are profitable and work on their farms under similar conditions. Information that currently exists about tile drainage water quality is collected from small plot scale systems (less then 1 acre). Producers are often skeptical of plot scale demonstrations when evaluating management changes for their fields. Results from these field scale demonstration sites provide a platform to educate farmers, agricultural professionals, and the non-agricultural community.

Drainage Demonstration Goals

  1. Evaluate water quality response of field scale subsurface tile drainage to rainfall and snowmelt events;
  2. Validate Best Management Practices (BMP’s) for crop response and corresponding environmental benefits;
  3. Evaluate pesticide and nutrient losses through a pattern tile system with typical weed control and nutrient management strategies;
  4. Evaluate & demonstrate new technologies on a “field scale” to determine water quality benefits; and
  5. Conduct educational events and promote water quality improvement strategies on tile drained cropland in southern Minnesota.

For more information about field scale drainage locations:

Automated monitoring equipment  Automated monitoring equipment 

Automated monitoring equipment monitors drainage flow volume, temperature, and rainfall. Automated samplers obtain composite samples that are analyzed through the Minnesota Department of Agriculture laboratory for pesticides, nitrate nitrogen, and phosphorous concentrations. Graduate studies at Minnesota State University in Mankato, Minnesota assist with monitoring activities, evaluation, and education outreach activities

An advisory committee comprised of commodity group representatives, ag-retailers, crop consultants, university researchers, agency personnel, and farmers meet quarterly to provide input and review of the proposed management practices and associated education outreach activities. “We wish to extend a big thank-you to all of our cooperators with this project”


  • Tom Hager - Red Top operator
  • Dan Reuter - Highway 90 operator
  • Farm Business Management
  • Greater Blue Earth Watershed
  • Minnesota Certified Crop Advisor
  • Minnesota Corn Growers
  • Minnesota Crop Production Retailers
  • Minnesota Independent Crop Consultants
  • Minnesota Pollution Control Agency
  • Minnesota Soybean Growers
  • Minnesota State University
  • Three Rivers RC&D
  • University of Minnesota
  • University of Minnesota Extension

Definition of Terms

  • Yield: One way to assess pollutant contributions from watersheds of different sizes is to determine the “yield” or the mass per unit area (such as lbs./acre) of a constituent coming out of a watershed during a given time period. Yield normalizes mass on the basis of area, and allows for more relative comparisons of pollutant contributions to be made between watersheds. Yield is calculated by dividing the total mass or load of a constituent by the area (acres) of the watershed.
  • Flow-Weighted Mean Concentration FWMC: Proportionately equivalent to normalized yield, the “flow-weighted mean concentration” (FWMC) is calculated by dividing the total mass or load for the given time period by the total flow volume. The FWMC is mass normalized for flow. Conceptually, a FWMC would be the same as routing all the flow that passed a monitoring site during a specific timeframe into a big, well-mixed pool, and collecting and analyzing one sample from the pool to give the average concentration.
  • Runoff: Runoff is the part of precipitation, including baseflow, storm flow, flow from ground water, and flow from point sources. Essentially, runoff is all the flow passing a particular location. To calculate monitoring season runoff, the total flow volume or the amount of water which passes by the station during the monitoring period is calculated and converted to acre-inches of water. This number is then divided by the total number of watershed acres to determine inches of runoff. Conceptually, this is equivalent to redistributing all the flow equally over the watershed, then measuring that water depth in inches.

MDA Contact

Ryan Lemickson
Fertilizer Field Unit

Pesticide & Fertilizer Management Division