Discovery Farms studies agricultural drainage systems to better understand and manage nutrient losses through tile systems. Fields with tile drainage have perforated pipes installed several feet below the surface. These pipes drain excess water from the soil profile, which can help alleviate saturated conditions and prevent surface ponding. Drainage systems are used to manage soil moisture for crop establishment, growth, and yield as well as the timeliness of field access. Although tile drainage has benefits for crop production and farm operations, it can also provide an easy pathway for nutrients to leave the field and enter nearby water bodies. As such, it is important to understand what management practices are needed in tiled landscapes to prevent unwanted nutrient losses.
Tile drainage is present on agricultural land throughout Wisconsin; however, it is most prevalent in the eastern part of the state where heavy soils and flat topography can limit drainage. Past Discovery Farms tile monitoring projects have focused on northeastern Wisconsin. Each monitoring site is located at a tile outflow and has equipment to continuously measure drainage volume and periodically collect water samples for analysis of soil, phosphorus, and nitrogen content. Some tile monitoring sites have been paired with surface edge of field stations to compare soil and nutrient losses in surface runoff versus subsurface drainage. Tile monitoring sites have drained row crop fields in dairy forage, grain, or canning vegetable rotations as well as grazing land.
Current Tile Monitoring Projects
Kewaunee County
Discovery Farms is monitoring a woodchip bioreactor in Kewaunee County, WI. This is an edge-of-field conservation practice used to treat tile drainage before being discharged downstream. The woodchip bioreactor is an underground trench filled with woodchips that intercepts the tile drainage. The woodchips act as a food source for beneficial bacteria that convert nitrate, a form of nitrogen needed for crop production but can have negative impacts on water bodies, into harmless nitrogen gas. By routing the tile drainage through the bioreactor, we hopefully have better water quality leaving the tile drainage system. This is the first tile drainage treatment practice that we have monitored. We are excited to learn more about the effectiveness of this practice in Northeast Wisconsin.
