Good enough drainage
Scrimp that next drainage project to save money and protect our lakes and streams.
Research shows that hydrology plays a critical role in delivering nutrient loads responsible for harmful algal blooms. Landowners can help by limiting subsurface drainage discharge to the minimum needed for crop response.
Producers may be able to lower construction costs with a new drainage systems. While payback in terms of yield can be significant from tiling, it involves a significant up-front investment. There are a number of planning guides available to help ensure the investment will pay-off. By laying just enough, producers can ease some of the construction costs. Calculate potential returns from a tile drainage investment with this Tool to Analyze Returns from a Tile Drainage Investment from Iowa State University.
Frugal plans could result in payoff for the environment as well. Soil purifies most of the world’s water. Installing subsurface drainage bypasses the natural filtering and cleaning processes of the soil. This can result in less pure water channeled directly to creeks, ditches, rivers and lakes. Less water infiltrates to groundwater too, meaning faster delivery of more rainwater to receiving bodies.
Scientific research is showing that increased loads from heavy rainfall coupled with extensive drainage projects are tied to the prevalence of harmful algal blooms. Some communities offer payback to landowners to set aside wet areas. A current list of financial incentives is maintained by the Michigan Department of Environmental Quality.
I discussed the study about drainage and its impact on Lake Erie published by Williams, et al with Ehsan Ghane, an assistant professor at Michigan State University Extension specializing in agricultural drainage.
He explained that when it comes to runoff, “We can’t control precipitation patterns, but we can influence how long the water takes to reach the watershed outlet.” If producers want to reduce P loading they can “slow down water flow from their field with a variety of conservation practices like controlled drainage, wetlands, saturated buffers, two-stage ditches, apply fertilizer wisely based on a 4-R approach, and keep the soil covered year-round.”
Ultimately, in regards to subsurface drainage he suggests to producers “as Dr. Wayne Skaggs puts it, drain the amount of water from the field that is necessary for crop production and not a drop more.”
Harmful algal blooms are a serious threat to freshwater systems. While careful nutrient management is important, managing runoff may be even more critical. Any action – or in this case – non-action – that can slow down the movement of water downstream will improve quality as well.