Shutting the gates
By LARRY KERSHNER
WOOLSTOCK – During the hot dry weeks of past crop years, Woolstock-area farmer Arliss Nielsen said he often thought of all the water that left his fields through tiling during wetter weeks.
He also thought of the nitrates that left with the water, the cost he incurred in getting it onto the fields in the first place and the cost of replacing it later in the season when his plants need it.
But 2015 is different, at least on 320 of his level acres. Nielsen has installed a controlled drainage system, where he can close tile gates at strategically placed structures and hold water back.
And to his surprise, Nielsen said, the structures can hold back quite a bit.
His system will be part of a Sept. 10 field day to show area farmers and contractors how the controlled drainage works, sponsored by the Natural Resources and Conservation Service, Iowa Learning Farms and Practical Farmers of Iowa. Speakers include Tim Smith, an Eagle Grove-area farmer and longtime cover crop user; and Bruce Voigts, of the Clarion office of the NRCS.
Troy Kastler, co-owner of K-Con Inc., of Woolstock, installed 160,000 feet of new pattern tiling in Nielsen’s fields – equivalent to 30 miles – in the 320-acre parcel.
He also installed 12 control structures of different sizes, depending on how many acres each structure was designed to keep watered, and six underground gate values.
The gate valves installed into the tile line and underground, work on a float system. As water pressure builds up behind the gate, it releases excess water, but as pressure reduces the gate closes, holding back the water that remains.
“It’s like a bathtub now,” Nielsen said of the how quickly the new tile drains. “Just pull the plug, and it’s gone.”
But this upside to patterned tiling is also the downside, Nielsen said.
The water hits the surface waters of the Eagle Creek quickly and with force. Eagle Creek is part of the Boone River watershed, and one of nine targeted watersheds for reducing nutrient loads from farm fields into surface waters.
It also carries costly fertilizer.
“When you see (tile) water running,” Nielsen said, “you see N going to. These structures hold the N in the ground.
“Otherwise it leaves the field faster than the plants can use it.”
A 25 bpa bump
Last year, Nielsen said he installed one control structure to hold water back on a 30-acre corn field, just to see how it worked.
“That 30 acres yielded 25 more bushels than the rest,” he said.
Kastler added that when trying to install the rest of the tile since harvest, he had to open the gates of the structure to drain the field, because the water level was just a few feet from the surface.
Nielsen said he’s been a longtime no-till farmer, who uses cover crops and a bioreactor to also keep nitrates and phosphorus out of surface water.
Kastler opened one of the structures and used a rod, designed to manually open and close the water gates inside, which showed 3 feet of water inside the structure.
That’s enough, Kastler computed, to back water up the tile a quarter mile.
That’s water and nutrients that are still available to corn roots, that otherwise would have been long gone down the watershed.
In a soybean field, Kastler said, a structure was holding back 4 feet of water.
“I’m impressed with how much they hold back,” he said.
Besides the six surface control structures, Kastler said he installed a series of underground water gates, one at each foot of rise.
“So not only is the gate holding back water,” Nielsen said, the underground gates are holding back another foot each.
Nielsen said he closed the water gates shortly after applying nitrogen on about July 2.
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