What is in this article?:
- The two-stage design has perforated tile lines that empty field water through side inlets in the ditch at a more stable place
- This is a low-tech, common-sense approach
- The slope of a two-stage ditch is one-half to two-thirds of a conventional ditch
How it works
“Nature creates floodplains all the time; we are creating them with a two-stage ditch,” says Joe Draper, The Nature Conservancy project director, Upper St. Joseph River, Angola, IN. “It’s much less invasive to aquatic invertebrates, mussels and fish than cleaning out a conventional ditch. Those organisms help maintain water quality.”
Farmer benefits are reduced bank erosion, scouring and flooding; less ditch maintenance; and less nutrient loss.
The slope of a two-stage ditch is one-half to two-thirds of a conventional ditch (represented by the dotted line in this diagram), greatly reducing banks’ shear stress.
The Nature Conservancy, which has spearheaded much of the two-stage ditch experimentation, has documented the following water-quality benefits compared to conventional ditches in Indiana and Michigan sites:
- A 14-20% reduction in total nitrogen runoff.
- A potential for 300-500% more denitrification as a result of the floodplain bench areas.
- A reduced water turbidity and suspended sediment.
Because the two-stage ditch is more stable, it might only need to be maintained every 20 years, if ever, says Draper.
“The two-stage ditch spreads water out across a broader section,” says Chad Watts, Nature Conservancy Wabash Rivers Initiative project manager, Winamac, IN. “This means less water force undercutting ditch banks.
“This design is a valuable conservation tool that needs to be used along with buffer strips, reduced tillage and best management practices,” Watts adds. “There is no one magic bullet.”
To learn more about two-stage ditches and view a related video, visit http://tinyurl.com/2StageDitch.