Mastering the Drainage Connection
Poor drainage undermines the effectiveness of precision agriculture, forcing planting delays and cratering yields. The following article demonstrates how one farmer adopted the principals of precision ag to improve drainage on his farm. Improved soil tilth translated into longer planting windows and better nutrient access for crops.
By: Darrell Smith, Farm Journal Media
In many areas, the words "drainage" and "tile" are synonymous. But for farmers such as Leon Wendte—a retired soil conservationist who farms with his brother Roy in south-central Illinois near Altamont—tiling doesn’t work on their Cisne soil.
Although highly productive and flat as a table top, the topsoil sits 18" above a virtually impenetrable claypan.
Until now, the only way to drain such soil was with shallow surface ditches, installed every year with a rotary ditcher. The operator had to guess, or remember from prior experience, where to run the ditches to carry water off the field. That’s almost impossible when land slopes only 1" to 3" per 100'.
Drawing upon his engineering and precision farming technology experience, Wendte designed "precision surface drainage" to place drainage channels exactly where needed. He uses topographic maps created from RTK planting files, a laser control (like tiling contractors use) and a pull-behind rotary ditching machine.
A third Wendte brother, Keith, created topographic maps of the family fields with contour intervals as low as 1.2". Superimposed on an aerial photo, the contour lines reveal where drainage ditches should be placed.
In a field where slope is undetectable to the naked eye, a topographic map with a 1.2" contour interval shows Leon Wendte where to place surface drainage ditches so they will channel water off the field.
"It costs several hundred dollars for a tiling contractor to survey and map an 80-acre field," Wendte says. "Keith mapped dozens of fields in a few days using Case IH AFS desktop software."
Following major drainage paths on the topographic maps, Wendte lays out A-B lines in each field. Identifying wet areas from scouting, field history, aerial photos and yield maps, he runs laterals from wet areas to main ditches that carry water off the field.
RTK auto-guidance steers Wendte’s tractor parallel to his A-B lines, the laser controls the grade and the ditching machine cuts a shallow, 5'-wide, flat-bottomed ditch. Successive passes shape the sides so the ditch can be crossed smoothly.
Wet no more. "Before this technology, we had to make a ditch 3" or 4" deep with a small-diameter circular bottom to get water off the field," Wendte says. "They were rough to farm over. Installed at random, they often were not in exactly the right place, and they did not have a uniform positive slope, so water still stood in pockets in the field. The channels were so small, we had to remake the ditches every year."
The contour maps showed Wendte why surface drainage had been frustrating for so long. "We never got swales drained properly because we never were able to put ditches in exactly the right place," he says. "In land this flat, you can’t do it by looking at the ground. Even if you’re only a few feet off with a ditch, you’ll still have standing water."
Wendte’s ditching machine, which can also be used to build waterways, cost about $50,000. It is designed for use with a 325-hp tractor, although Wendte pulls his with a 275-hp tractor.
His other out-of-pocket cost was $20,000 for the laser grade control and automatic tractor hydraulic hookup. He already had RTK auto-guidance and software for making topographic maps from as-planted maps. "On our acreage, the investment should pay for itself in about three to five years from higher yields resulting from better drainage," he says.