Drainage Management Systems
There are concerns about how subsurface impacts water quality, movement and distribution. In the Red River Valley – a region that includes North Dakota, Minnesota and Manitoba – landowners, along with local, state and federal government agencies, agricultural businesses and the University of Minnesota, are working together to tackle these concerns.
Tile drainage is accused of increasing downstream peak flows, causing flooding, moving soil and sediment and making it easy for nutrients to move. Imagine a tile drainage system with no surface inlets. Research has shown it does not increase downstream peak flows; flooding is not increased. The existence of tile drainage encourages infiltration, which reduces overland flow. The reduced overland flow reduces the amount of sediment (topsoil) movement. Recent research suggests there is less phosphorus movement through the tile.
The drainage system along the primary runway at Scott Air Force Base in St. Clair County, IL, was originally clay pipe and perforated corrugated metal pipe. After 50 years, much of the pipe was either leaking severely or had deteriorated to the critical point where replacement was required. Plans called for nearly six miles of large-diameter pipe to be installed, but it had to be done within a strict timeframe, because the runway could be shut down for only a specific time period.
The Agricultural Drainage Management Coalition (ADMC), Agricultural Drainage Management Systems Task Force and Dan Jaynes with the National Laboratory for Agriculture & The Environment collaborated to demonstrate and evaluate saturated buffers at field scale to reduce nitrates and phosphorus from subsurface field drainage systems.
What do you get when you put a Michigan dairy farmer and a conservationist in a car for several hours? If the dairy farmer is Blaine Baker, co-owner of Bakerlads Farm in Clayton, and the conservationist is Thomas Van Wagner, technical co-ordinator for the Lenawee Conservation District Center for Excellence Program, you get the initial designs of a livestock reservoir wetland sub-irrigation system.
It’s a short jump to change many drainage systems into drainage subirrigation systems, says Mark Nussbaum, an area engineer at the United States Department of Agriculture - Natural Resources Conservation Service (USDA-NRCS). Add a bioreactor intended to eliminate water pollution and it equals good news for farmers and the environment.
Nitrate loss through tile drainage systems has been a water quality concern in the Midwest for many years. Reducing concentration from current values to a maximum level of 10 mg N L-1 has been adopted as a goal in many nutrient reduction plans.
The importance of good water management is sometimes lost in the busy world of farming. As an Australian Nuffield Scholar, travelling to the United Kingdom, the Netherlands, the United States and Canada to gain knowledge on ways to reduce waterlogging, I soon realized the importance of looking at multiple ways to combat this issue.
Researchers are in agreement; too much phosphorus is finding its way into field tile. But rather than demand a moratorium on tile drainage installation, many are suggesting more practical drainage solutions for the agricultural industry.The problematic algal blooms that are plaguing Lake Erie are being fed by high concentrations of phosphorus, particularly between March and June each year. Although there are many contributing factors to the growing problem, the timing suggests agricultural sources may be significant. After heavy rains in the spring of 2011 spawned the largest algal bloom in Lake Erie’s history, the International Joint Commission, which was created by the Boundary Waters Treaty to prevent and resolve disputes between Canada and the United States, formed the Lake Erie Ecosystem Priority (LEEP). In a report released last year, the organization identified that non-point sources (which include agricultural operations) truly are contributing more than 50 per cent of incoming phosphorus loads. Douglas Smith, a soil scientist working with the United States Department of Agriculture’s Agricultural Research Service (USDA ARS) in Temple, Texas, has a dominant interest in phosphorus transport. Between 2004 and 2013, he was involved in research that aimed to clarify the impact of conservation farming practices on the Lake Erie basin, and found several undesirable effects on the amount of phosphorus entering the watershed. No-till, for example, doubled soluble phosphorus loading compared to rotational tillage (tilling only before planting corn). But in the same study, Smith found it also decreased total phosphorus loading by 69 per cent compared to rotational tillage. Similarly, grassed waterways increased soluble phosphorus loads, but not total phosphorus. Only the recommended rotational practice of planting corn, then soybeans, wheat, and oats reduced both soluble and total phosphorus loads (by 85 per cent and 83 per cent, respectively) compared to the standard corn–soybean rotation. Now researchers are concluding even the best farming practices can’t be solely depended upon to protect the lake and Smith is offering a piece of advice to drainage contractors.“Be aware that drainage may have a target on its back,” he warns. Both the International Joint Commission and the Ohio Phosphorus Task Force set phosphorus loading reduction targets of 39 per cent and 37 per cent respectively in 2013. In looking for ways to make those targets a reality, Smith says he personally has already been involved in multiple studies focused on tile drainage discharge. What he was surprised to discover in research fields was that as much as 49 per cent of soluble phosphorus and 48 per cent of total phosphorus losses occurred through tile discharge.“The water was hitting the tile much quicker than what I was expecting,” he says. “Our peak discharge in surface runoff happened at almost the exact same time as the peak discharge in the tile flow, so there’s a lot more surface connection through macropores, root channels, worm holes, and soil cracking in the region than what I had realized.”Smith says these preferential flow paths have proven to be more pronounced in certain soil types. Kevin King, an agricultural research engineer also with the USDA ARS, but located in Columbus, Ohio, says most of the soils in Ohio are poorly drained and couldn’t be farmed without tile. They also tend to be soil types that are prone to developing preferential flow paths. “We did a review article for the Journal of Environmental Quality and the fine textured clay soils will have more losses than your sandy soils due to preferential flow paths, even though phosphorus will bind to those clay particles,” King says. The fact that clay binds phosphorus only further complicates the problem as farmers increase fertilizer rates accordingly. King notes that if farmers in Ohio were applying phosphorus fertilizers through subsurface placement, this may not be as much of a problem, but the most common practice still seems to be broadcast application. “If we have preferential flow paths that develop in fine texture soils, then any water that migrates into those is carrying that rich phosphorus off the surface, into the tile.”North of Lake Erie, subsurface application of phosphorus seems to be more common. Merrin Macrae, an associate professor at the University of Waterloo in Waterloo, Ont., together with a team of surface-water chemistry students and the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) recently concluded a study of field surface runoff and tile systems effluent from Ontario cropland. Between May 2012 and April 2013, this research team demonstrated that although tile sources contributed 78 per cent of total runoff at one research site, surface runoff contained 81 per cent of the soluble phosphorus lost and an equal amount of total phosphorus. Their other site produced similar results. But in the first year of data at a new high clay site, tile drainage played more of a role relative to surface runoff. Macrae says that although there’s still a lot to learn, especially about the role of soil type, their research produces some clear lessons.“Overland flow has much higher concentrations of phosphorus than our tile drainage effluent,” Macrae says. The challenge, as far as she’s concerned, is keeping that surface water from running directly into tile systems. “I’m not saying tiles are not a phosphorus source, but they seem to move phosphorus at a lower rate partly because of the soil types at our sites and how they are managed.”For example, Macrae says it is clear a surface inlet that takes field runoff right into the tile drainage system is disastrous from a phosphorus standpoint. That’s why she’s working with OMAFRA’s Kevin McKague to promote the use and proper construction of surface water treatments such as water and sediment control basins (WASCoB). Macrae says she doesn’t think people outside of the research community have any idea just how much beneficial collaboration is currently in progress, on both sides of the border.“The research that’s gone on for the last four or five years has very much been a collaboration between governments, farmers and researchers working together to get the right answers,” she says. King agrees that a lot of good collaboration has gone into addressing the issue so far, but he believes meeting phosphorus reduction targets is going to require the help of even more contributors. “How we get from science to implementation is where drainage contractors, ag retailers and the governments fit,” he says. “It’s all of our responsibilities to not only learn the science, but then to relate that to the producers to get that implemented.”King believes drainage contractors are well equipped to offer advice to farmers when installing tile systems, taking soil type and farming practices into consideration. Farmers that broadcast fertilizer and practice no-till on a high clay content field need to hear about the effects of artificially adjusting the outlet elevation of their tile. “If we raise that outlet elevation to 16 or 18 inches from the surface during the winter months, we have the potential to reduce the amount of water leaving the site anywhere from eight to 45 per cent,” he explains. During winter months, when phosphorus losses start to rise, King says drainage control can reduce the amount that’s leaving the site anywhere from 40 to 65 per cent.King also recommends blind inlets, sometimes also called French drains, in a no-till system. Smith says they’re absolutely perfect for closed depressions and pothole sites. “Blind inlets are basically an alternative practice to tile risers,” Smith said. “We put them in at the lowest point of potholes and we got pretty good reductions for phosphorus, in the neighbourhood of 40 to 80 per cent phosphorus reduction depending on the year.” Smith says that in the comparative study conducted over six years, he found that sediment and nutrient loads were particularly improved during extreme weather conditions such as the wet spring of 2010. The study was so conclusive, it led to the development of a Natural Resource Conservation Service Standard for installing a blind inlet in Indiana. King says they’re currently looking into improving this system even further by back-filling the leach field with steel slag rather than pea gravel, which would offer greater phosphorus binding properties, but the effectiveness of these strategies is yet to be determined. King says there is still a vast amount of research to be done.“Right now we’re putting band aids on a severed arm, just trying to stop the bleeding,” he says. “We’re going to have to stack practices and we have to understand that what works on one operation may not work on another.”Smith agrees, noting that even now there are a number of research projects that could prove very effective. He also agrees one size certainly won’t fit all and there will potentially be lots of new practices for drainage contractors to get involved in developing.
The beautiful established scenery of an old golf course can rarely be beaten, but history can come at a price when standing water threatens course closure. One thing we can all be fairly sure of is that weather patterns are changing and, global warming aside, that appears to be something that is here to stay.
An increase in the use of an innovative drainage system called “drainage water management” is being promoted by the U.S. Department of Agriculture’s Natural Resources Conservation Service in Illinois and other states in the region, as it provides significant benefits for both farmers and the environment.Drainage water management (DWM) allows farmers to control the amount of water that’s drained from the top few feet of the field’s surface. A box-like structure is attached to existing drainage pipe near the field outlet, with a number of large thick bars that can be inserted or removed to control water flow. It is similar to controlled drainage systems being used in Ontario, which employ a round structure and vertically movable panels.The DWM system provides a myriad of monetary and environmental benefits, from boosting crop yields to improving water quality of nearby watersheds through preventing nutrient run-off. “Farming is a risky business, subject to all kinds of influences like weather and global economics that are out of the producer’s control,” notes Dr. Ruth Book, an Illinois NRCS state conservation engineer. “With DWM, the farmer can decide when to drain the field and when not to. Think about how helpful this could be in a drought year, for example. If the producer knows that the summer is going to be hot and dry, he or she could hold back some of the water from the spring rains.” DWM can be installed with both new and existing tile drainage, but the field should have a slope of less than one percent. If that sounds restrictive, consider that in the state of Illinois alone, DWM is suitable for use in nearly 10 million acres of fields. There are now 14 counties in Illinois that are targeted for DWM demonstration projects. Many installations have already occurred through technical and financial support from the Natural Resources Conservation Service (NRCS), and more are in the works. This year, NRCS sponsored a special DWM project in the 37 square-mile watershed around the town of Tovey in collaboration with the Christian County Soil and Water Conservation District. Book says the predominantly flat, tile-drained cropland in that area of Illinois is very suitable for DWM. “The partnership goal is to help producers implement DWM and related practices on at least 20 percent of the cropland in the watershed over the next five years, or approximately 750 acres per year,” she explains. “The expectation is that this achievement will demonstrate a measurable improvement in surface water quality entering nearby Sangchris Lake.” It goes beyond the lake, however. Fertilizer use in Illinois crops is a major contributor to the nitrogen load in the Mississippi River Basin. About 90 percent of the nitrate-N that’s discharged via the Mississippi River is due to agriculture, Book notes. Research has shown a definite correlation between tile drainage and high nitrate levels in surface water, and although there seems to be an apparent conflict between needing to drain fields for crop production and the need to reduce nitrates entering surface water, Book says DWM is a way to accomplish both. “During fallow periods, the water table is raised, creating conditions that are very similar to what the field was like before the drainage system was installed,” she says. “Also, the water table can be raised during the cropping season to retain water that would have otherwise drained away, potentially supplying water to the capillary root zone of the crop, but also reducing nutrient loading.” The effectiveness of DWM in reducing runoff is directly related to the volume of drainage water that is retained in the field, so operators are encouraged to keep the system closed, draining the field only when necessary to grow crops and do field work. Contractors, training and next stepsBook praises the Illinois Land Improvement Contractors Association as “a great partner” in the effort to spread DWM use. “Drainage contractors not only help us sell drainage water management and other conservation practices related to drainage, but they also are out there on the front line, actually installing,” she says. “Most drainage contractors already have the equipment they need to install drainage water management. Implementation is quite simple, usually involving just the addition of a water control structure at strategic places in the drainage system.” Flat fields can often be managed with a single water control structure, but Book says it’s possible to stair-step the DWM system to accommodate changes in elevation. She explains that when the field has more slope, it’s helpful to lay out the drainage system so farmers can manage the water table with the minimum number of structures. “We’ve had many drainage contractors attend training sponsored by the Agricultural Drainage Management Coalition and NRCS,” she explains, “where they learn how the drain system layout can be changed to facilitate DWM.” Illinois is part of the 10-state focus area in the NRCS Agricultural Water Management effort to spread the installation of DWM, but it’s the state with the longest history of DWM use and the one with the most suitable acres. Following in Illinois’ footsteps, some of the other nine states are offering financial assistance and considering the development of special regional DWM projects. In a few years, Book believes Illinois District Conservationist Tony Hammond will be able to report a dramatic increase in the adoption of DWM in Christian County. “Tony and the staff at the U.S. Department of Agriculture field office in Taylorville have been publicizing the great things DWM can offer, and he’s beginning to show some results. Now that we have our conservation professionals trained on the practice, I think we’ll be seeing much more implementation of DWM all over the state.” With all the benefits provided by the system – and the strong support being offered – DWM is poised to become the standard on flat farmland in the U.S. and beyond.
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Ohio LICA Convention
January 3-4, 2019
New York LICA Convention
January 6-8, 2019
Illinois LICA Convention
January 9-12, 2019
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January 9-11, 2019
Iowa LICA Convention
January 13-15, 2019
Nebraska LICA Convention
January 15-18, 2019