• Quantify reduction of P loss in drainage water with controlled drainage. Results will inform producers and policymakers if controlled drainage can contribute to the 40% target of phosphorus reduction in Lake Erie and other water bodies in Michigan. We will gauge success of our project, if we can develop a management guideline for controlled drainage to contribute to the goal of 40% reduction in P loss.
• Present producers and policymakers with the cost of reducing P loss with controlled drainage.
• Show producers the fate of P and N from fertilizer application, and allow conservation practices to be targeted to the most vulnerable periods of the year where P loss is greatest.
• Show producers whether the high water table under controlled drainage increases evapotranspiration that indicates more water available for crop use.
• We will communicate results to the entire soybean industry through the following:
1) A factsheet to explain the general aspects of controlled drainage, so soybean producers understand its functionality and farm suitability;
2) A factsheet to show results of nutrient (DRP, TP, and nitrate) reduction;
3) One professional 3-minute video to communicate the general aspects of the system will be recorded on the farm;
4) Conduct two field days;
5) Conduct short 1-minute videos for the MSU Extension Twitter account;
6) Presentations at local and state meetings.

Project benchmark includes completing the calibration period by October 2019, and starting the treatment period from September, 2019. During both these periods, flow and nutrient data will be collected and analyzed. We will collect enough data points during the calibration period to have a meaningful statistical analysis at the end of the project.

Updated May 1, 2020:
The primary goal of this project is to investigate the effectiveness of conservation drainage practices in reducing phosphorus loss from subsurface-drained farms. This on-farm experiment is comprised of two sites with controlled drainage. Both sites have been fully instrumented to collect flow and water quality data. We have been collecting flow and nutrient concentration data during water year 2019 except for the periods with instrument malfunctions and subsequent data loss. We will continue to collect data until the end of water year 2022 (i.e., Sep 30, 2022), after which we will make a conclusion about the effectiveness of these conservation drainage practices.

Our preliminary data shows that phosphorus movement in the soil is highly dependent on the subsurface drainage volume. Generally, higher flow volumes were associated with higher dissolved reactive phosphorus (DRP) and total phosphorus (TP) concentrations. Therefore, conservation drainage practices should be designed to target high flows, if we are to reach the target phosphorus reduction of 40% set by EPA. Unlike phosphorus, nitrate concentration showed a seasonal trend where concentration reaches a peak in spring followed by steady decline that continues into fall.

Other stakeholders have funded different aspects of this project including MDARD, EGLE, Michigan Alliance for Animal Agriculture, Corn Marketing Program of Michigan, and Michigan Soybean Promotion Committee. Data generated from this project is not only useful for determining the effectiveness of conservation drainage practices, but they can be used in modeling and simulation efforts to investigate the impact of conservation practices on water quality.