FebruaryFebruary 2014

® IrrigationA Penton® Publication Extra Drain and irrigate: best of both worlds PHOTOS BY MARK NUSSBAUM

By LYNN BETTS Key Points

t’s expensive up front, and it doesn’t ■ Payback is quick for subsurface work everywhere. But a relatively new - systems. Iconservation drainage and subirriga- ■ The combo systems work only on tion combo that’s catching on in Missouri with impermeable layers. and drawing interest in Minnesota has a ■ quick payback — and other benefi ts. Drainage-irrigation systems offer In soils with a restrictive layer at about consistent yields year after year. the usual tile drainage depth, tile drains are being designed with water control logs to control the level, says structures to both drain excess water and Nussbaum. “In-line water control struc- to add water back into the profi le, as tures have removable stop logs that can needed. help store rainfall in the tile and the soil “There are about 2 million acres of profi le, or raise and maintain levels from soils in Missouri where this subirriga- water pumped into the tile from wells. The tion and drainage duo could apply,” says water wicks up from the tile line as much John Hester, USDA Natural Resources as 20 inches, to within about a foot of the LITTLE TO SEE: The control box with stop logs is all there is to see with controlled Conservation Service area engineer, surface. It’s available to plants when they drainage and subirrigation systems, except for optimal yields. One of the first systems Bloomfi eld, Mo. Hester and fellow NRCS need it.” Mark Nussbaum helped design yielded 72 bushels of soybeans/acre in droughty 2007. engineer Mark Nussbaum of Jackson, Because water is absorbed and held Mo., have helped farmers install systems in the soil profi le longer, water-quality NRCS soil scientists investigate sites to de- on 2,500 to 3,000 acres, mostly in Cape benefi ts accrue with the dual system. termine the depths to restrictive layers. Girardeau and Scott counties in the south- Controlling water in the system can reduce “We’re seeing the cost of a dual eastern part of Missouri, over the past 10 overland fl ows by 29% to 65%, and peak drainage-subirrigation system is about years. runoff by 15% to 30%, according to NRCS. 20% higher than for drainage only,” Hester “Subirrigation with tile doesn’t work The system cuts phosphorus loss up to says. “For that relatively small add-on, where the restrictive layer is closer to the 45%, and sediment loss from 16% to 65%. some farmers are opting to set up now surface, or where the soil is highly per- with closer spacing, even if they don’t use meable without a clay layer,” Hester says. Retrofit or new system the water control structures now for sub- “But it can work really well on fl atter soils Drainage-subirrigation systems can be irrigation.” with a restrictive layer at that 4-foot depth retrofi tted to existing tile, but most of the Betts writes from Johnston, . or deeper. Those waterlogged soils are dif- Missouri systems are being installed in fi cult to plant in the spring. The soil needs brand-new tile lines, Nussbaum says. The ■ See more on this topic beginning on tile for drainage then, but later in June and difference in the dual use from drainage Page IE 2 July it gets dry, and you want that water only systems is tile spacing: Maximums back in the soil profi le.” for pattern drainage only are 60 feet lat- WATER WICK: In soils with a restrictive “The tile that drains excess water in eral spacing, but for subirrigation the layer at about the tile depth, blocked drainage mode can also be used to hold maximum is 45 feet. tile or tile pumped full of water results the water table high enough in the soil Most systems are in creek bottoms, in in water wicking upward, as close as a profi le that water can wick up to the crop 10- to 40-acre fi elds. The fi elds are typically foot from the surface. That’s how water root zone in irrigation mode,” using in-line very wet in spring and fall, but fertile, with control structures can be used to both water control structures that have stop a restrictive layer about 4 to 6 feet down. drain and subirrigate land.

INNOVATIVE, PROVEN & TRUSTED FOR OVER 50 YEARS! GOOSENECKS UP3 EASY CLEAN ˆ2SRGSVVSWMZI PRESSURE 9:VIWMWXERX NOZZLE SENNINGER thermoplastic reduces Invented REGULATORS ® plugging from rust ˆ Conveniently pinch and pull Wobbler 1EMRXEMRGSRWXERX ¾EOMRK to remove the nozzle; Technology preset outlet place and click to re-install. in 1978! pressure to ˆ]IEVWSJ optimize system proven ˆ2SRIIHXSHMWEWWIQFPI performance. performance the sprinkler MRXLI½IPH ˆ %ZEMPEFPIMRM;SF

[[[WIRRMRKIVGSQˆ1EHIMR97%