Drainage Management Systems
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.
On flat cropland, controlled drains may become the new norm in Ontario, replacing conventional tile drainage on many of the province’s farms. The flexibility of controlled drainage delivers benefits for farmers and the environment that standard drainage cannot offer, and the use of these systems is spreading accordingly.
While drainage technology has been improving the productivity of farmland clear across the continent, the Cisne soils of south-central Illinois have stubbornly resisted progress. But the Wendte family has proven more persistent than even the land itself.Leon Wendte was armed with a degree in agricultural engineering and 33 years of experience when he retired from his position as New Hampshire’s state engineer for the Natural Resources Conservation Service and came home to the family farm. His brother, Roy, was growing more than 5,000 acres of corn and soybeans near Altamont, Ill., and surface draining the farm exactly the same way farmers have for centuries in that part of the state.Tile drainage is impossible in this area, thanks to glaciation and natural geology, says Wendte. First, there’s an impermeable clay pan layer about 18 inches below the soil surface and second, he says, there’s no more than one to three inches of slope for every 100 feet of land, which really offers water no place to go. “Where most farmers put in tile to lower the water table, we have to rely on evapotranspiration,” Leon explains. Their only other alternative is to grade surface ditches at the same slope most contractors would install a tile drain or lateral. But even the most experienced struggled to maintain margins of error less than a tenth of a foot, grading surface ditches with whatever machine might be available. In years past, farmers have used spade and shovel, mold board plow, and tractor-mounted blades, box scrapers, or small rotary ditchers. On the Wendte family farm, this meant approximately 500 acres remained improperly drained. So Wendte looked to precision implements for improvement.Equipped with a Wolverine rotary ditcher and laser controlled hydraulics, Wendte has installed three- to six-inch deep, five-foot wide, flat-bottomed, surface ditches on over 300 acres in the last three years. He says he slopes the banks on a 10:1 ratio, “so that you can drive a sprayer across it at 12 to 15 miles per hour and not even feel it,” and focuses on the worst fields first. But Wendte also accredits his brother Keith with providing a critical piece of their precision surface drainage system: the topographic maps he uses for planning.“All our tractors have autosteer and on our farm we’ve found it cost effective to install our own base station, so we generate our own RTK correction factor accurate to one inch or less,” Wendte explains. Using Case IH AFS desktop software, their ‘As Planted’ records, and aerial photos, Keith saved the family hundreds of dollars in survey costs, and it only took him a few days to pull everything together.” So for all 100 fields that we have, I have topographic maps accurate down to a two or three inch contour line just waiting to be used,” Wendte says.A lot of time goes into planning his drainage systems long before any earth is ever moved. Wendte follows natural drainage paths on the maps Keith made, taking into consideration wet areas identified during scouting, in field histories, on aerial photos and indicated on yield maps. He plans laterals from wet areas to the main ditches to carry water off the field. An AB guidance line is created on the maps for each surface ditch so that when installation begins the exact location and alignment of the channel is transferred from the maps to the field. All of which, he believes, a drainage contractor would find pretty instinctive.“Any tiling contractor can use the laser equipment and smarts that they already have to install a drain over the surface of the land, in addition to the tile that they install below the soil surface,” he says. He thinks that if more contractors combined surface drainage with subsurface work, everyone would save more money on their field drainage. “When you have a wet field, it is far more economical to drain whatever water you can off the surface with a surface drain than it is trying to install tile and let the water that’s ponded on the surface infiltrate through the soil and then out through the tile.”He knows some contractors realize this, but not all. In defense of those who never give much thought to surface drainage, Wendte admits that some fields will not lend themselves to be surface drained. Surface drainage wouldn’t work on prairie pothole soils, for example, where depressions can fill up to two feet deep. But he insists that his family is getting the same benefit from their surface drainage system that they would with systematic tiling at a fraction of the cost, and contractors who can learn to use precision techniques on the surface will, in his opinion, offer customers more bang for their buck.“The combination of surface drainage and subsurface drainage is by far the most cost-effective and best working system you can have on a wet field,” Wendte says. “Just let your tile work that much more effectively, remove more gallons of water off your field in a shorter period of time, and take the pressure off your tile.”
Dec. 11, 2013, Algoma, ON – The Agricultural Tile Drainage and Storage Study for Algoma District has identified investment needs of approximately $6.5 million for agricultural infrastructure improvements, including land drainage, according to Wawa-news.com. | READ MORE
Sept. 9, 2013 – As Denis Rogerson, a drainage commissioner in Norfolk County, Ont., noted in the 1975 issue of Drainage Contractor, preventative maintenance is an important part of open-ditch drainage. Read more in this week's Forty-year flashback article.
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