Extension Ag Update
November/December 2003
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Field Drainage More Than Just Tile

Stanley (Jay) Solomon, Jr., Extension Educator, Engineering Technology, East Peoria Extension Center, 309-694-7501

Can you install your own tile cheaper? How should a drain tile system be designed? Would more surface drainage ditches be cheaper to install than drain tile? The increasing availability of tractor pulled tile plows have generated interest and discussion for farmers, landowners and researchers. While there are not any hard and fast answers for these questions, most farmers can answer for their own situation with a little time spent "pushing a pencil" by reviewing the basics of drainage design and some cost estimates.

Most producers realize that good field drainage involves more that just installing some drain tile. They know to design the drainage system before installation starts. The soil type, topography, amount of water to be drained, outlet options, and cost will influence the drainage design decisions. Soil type and topography make a big difference in the type and amount of drainage a field may need. Tight soils and steep topography will respond best to a surface drainage system. Most level soils with good hydraulic conductivity will respond well to subsurface drainage. Frequently a combination of surface and subsurface drainage will produce the best results.

In addition to the soil type and topography, the amount of water to be removed can have a major impact on drainage options. The amount of water to be removed is based on the surface area to be drained including any adjacent area that is of slightly higher elevation. This seems so logical, but underestimating the surface area and water produced can result in poor system performance and system failures. Complete topographic mapping of the field and surrounding area is the best place to start to insure proper system design.

Now the drainage system can be designed to meet the physical needs of the field. The drain tiles can be installed in random patterns, parallel, or herringbone patterns based on the topography and water to be removed. Random systems have been the traditional method used to dry "wet" spots in the fields. Herringbone pattern works well in narrow depressions. Parallel systems have generated considerable interest as a way to increase productivity for flat, regularly shaped fields. These systems could be used to control the water table under a field and promote better yields during wet years.

How to install the system? Equipment manufacturers are promoting tractor drawn tile-plows for producer installation of tile systems. The significant reduction in installation cost is driving the interest in the equipment. There are two distinct issues of concern currently in debate about this equipment: the uniform depth control capability of the equipment and system design knowledge of the producers. The uniformity of installation by various tile plows is the subject of current research in Ohio and other locations. One of the first bits of information released from the research has been that operator knowledge and skill has a major impact on the operation of this equipment. The problem areas identified were equipment operation, proper drainage design, and importance of depth uniformity in installation.

Installers using tile plows need to exercise the same care as trench system installers to insure proper depth control. Some things to beware of are operating the equipment faster than the sensor can react, trying to install deeper than the equipment is capable of handling, and improper calibration or leveling of sensors. Your equipment dealer should be able to help you overcome these problems. Also, installers need to allow for the stretch and shrink characteristics of tile pipe. Other issues installers should be concerned about are pipe size need to handle flows, slope of the pipe, and maximum pipe lengths for effective drainage. As these issues are interrelated and must be determined for each field individually.

Everyone interested in new drainage information and the revised Illinois Drainage Guide should put the “What’s New in Drainage?” workshops on their calendar for February. What everyone should know about drainage system design and installation issues will be the theme of the workshops. To find a location close to you, call your Extension office or check the University of Illinois Extension Calendar http://web.extension.uiuc.edu/cie2/offices/calendar.cfm