One of the topics that the House Agriculture and Forestry Committee has followed for the last several years is tile drainage. For a while, tile drainage was viewed as a bad agricultural practice by those in the environmental community, and it was suggested that the practice be curtailed.
The last time we had a briefing on tile drainage was several years ago. We were aware that the Miner Agricultural Research Institute in Chazy, New York, and UVM Extension have been doing research on the subject, so we invited the scientists doing the work to our committee for an update. It should be noted that there are strong ties between the Miner Institute and Vermont.
Among other things, our 2+2 students attend Miner during their college experience, and it is frequently a highlight for them because of the hands-on nature of the work.
For those who don’t know what tile drains are, a brief explanation is in order. Tile drains are essentially pipes with holes on the dorsal side when they are laid horizontally. This allows excess moisture to seep into the pipes, thereby lowering the water table and allowing for more activity, especially on certain types of soil such as clay. When the drains are installed, they are laid several feet below the surface and on a slight slope, so the water drains in one direction to a central collection area.
Our first witness was Laura Klaiber, from Miner Institute. Ms. Klaiber earned her Bachelor of Science degree in Ecology at the State University of New York in Plattsburgh and her Master’s degree from the University of Vermont in soil science. She is particularly interested in researching “how different management practices influence field hydrology, erosion and the export of nutrients to surface waters.” Her work has focused on phosphorus (P) runoff, which is so important to the cleanup occurring in the Lake Champlain watershed.
The question we have been asking ourselves is whether tile drains increase P runoff or not. Ms. Klaiber’s research indicates that the majority of P loss occurs in surface runoff (not tile drains) due to higher P concentrations, but those losses represent a very small fraction of the P that is applied to soil. In fact, the majority of the “loss occurs during a very short window of time,” when crops are not in the ground during snowmelt or during extreme precipitation events when applied manure has not had a chance to be absorbed. Her recommendations include being careful when manure is being applied: surface application should include some incorporation and weather should be noted. It is preferable to apply manure when there is no expectation of precipitation, and the areas where there is already high levels of legacy P should be avoided.
Ms. Klaiber’s caution about spreading manure on tiled land concerns macropores that form when the land dries out. Macropores are large cracks that form, creating a direct line to the tiles drains below. An extreme precipitation event just after a manure application can cause P to go directly into the tile drain rather than filtering through the soil. This is particularly true in heavier clay soils or on no-till fields.
One big take away from Ms. Klaiber’s work is the clear reduction of P runoff from tile drains, significantly less than that in surface water. These data indicate a much different picture than what was previously thought to be the case.
Our second witness was Joshua Faulkner, a Research Assistant Professor and the Farming and Climate Change Program Coordinator at UVM Extension. He does “applied research and outreach on soil, water, and nutrient related issues across the state and provides technical assistance to farmers on practices and innovative solutions to improve the management of these resources. His work spans from the farmstead to the watershed scale.”
Dr. Faulkner’s research indicates much the same results as Ms. Klaiber’s in terms of decreased levels of P in tile drain runoff. Some of the other benefits that come with tile drainage are improved “crop production and less year-to-year variability.” It also allows for field operation earlier and later in the growing season. Data from Ohio and Ontario indicate significant crop yield increases due to tile drainage ranging from 23% to 42% depending on the crop.
As climate change brings more extreme precipitation to the Northeast, farmers need to adapt, and tile drainage seems to be one of the tools available to them. It involves a significant investment in terms of money but the farmers who have made that investment feel that it has been well worth it. It is also good to know that the feared increased nutrient runoff, including P and nitrogen, doesn’t seem to be the case.
Additionally, I’ve viewed the use of tile drains as an opportunity since they drain into a central location. This aspect provides a chance to deal with the nutrients that might be contained in the runoff before it gets into the waters of the state.
Between 2001 and 2010, excess moisture (60%) and hail (26%) were responsible for an overwhelming majority of crop failure in Vermont. Strategies that reduce the amount of moisture in the soil (tile drainage) and increase the amount of organic matter (cover cropping and low- or no-till practices) will make the soil more productive and resilient going forward.
As we face the future that climate change is bringing us and the desire to help with phosphorus and nitrogen reduction in our waters, as well as sequestering carbon by using regenerative practices, tile drainage appears to be providing our farmers with another tool in the toolbox. I look forward to more research being done by Miner and UVM Extension to determine if there’s evidence of pesticide residuals coming out of tiles.