Planning an ag drainage system
By DARCY DOUGHERTY MAULSBY
Farm News staff writer
DES MOINES – Subsurface tile drains have long been an important tool to improve the productivity of Iowa’s farmland, and today’s land improvement contractors and farmers are looking at new options to maximize tiling while protecting soil and water quality.
“Tiling offers one of the most effective ways to boost your crop yields without changing seed populations, herbicide rates and other inputs,” said Dr. Matt Helmers, an Iowa State University Extension agricultural and water resources engineer who spoke recently at the Iowa Land Improvement Contractors’ Association’s 53rd annual meeting in Des Moines.”They aren’t making any more land, so we need to do the best job we can with it.”
It pays to properly size your mains, added Helmers, who noted that under-designed tiling systemscan impact yield by as much as 25 percent. “When you start with a good foundation, you can add more laterals to it, as needed, to optimize the production you’re getting from each acre.”
ISU researchers have also been studying the benefits of shallower drain placements, which can help curb nitrogen loss. At a site near Crawfordsville in southeast Iowa, researchers have compared 2.5-foot to 3-foot drain depths with 4-foot drain depths at 60-foot spacings. They’ve observed up to a 40 percent reduction in the volume of water coming out of the shallower drain lines, which reduces the nitrate load by about 40 percent.
“It’s not changing the nitrate concentration, but it’s short-circuiting the nitrate load to the stream,” said Helmers. He added shallow-drainage functions like year-round controlled drainage.
“Also, we haven’t seen a yield decline with the shallower drainage. This shows that you can influence not only the land’s productivity, but water quality with drainage practices.”
You can contact Darcy Dougherty Maulsby by email at firstname.lastname@example.org.
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