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- Dave Liebl was doubtful about building a dam in the middle of a field, but his wife Karen convinced him that something had to be done to halt the gully erosion eating away their topsoil. “Now I think it’s one of the best things I’ve done.”
- The Liebls’ first two water- and sediment-control dams were so effective at halting gully erosion that they invested in five more for other fields. “We haven’t lost one bit of production from the dams,” says Dave. On the contrary, he says, before the sediment dams were installed, “there were places where we didn’t get a crop because of the gully.”
- To other doubters, Dave says: “Some complain about having to farm around them, but it’s a small price to pay for keeping your soil.”
Water- and sediment-control basins are a time-tested way to prevent field gullies in hilly fields with irregular topography, says Jeff Hellermann, NRCS district conservationist, Stevens County, Minn.
Designed to be farmed over
In a productive field, “I’d go with a sediment dam versus a grassed waterway,” says Alberta, Minn., farmer Jim Krosch. In 2004, he installed four, 4-ft.-tall sediment-control dams to intercept runoff in a field that falls 8 ft. in half a mile.
“Water would cut gullies in the field every year. We’d work them shut with a digger; then they’d wash out again. We were losing a lot of soil. Now there’s very little erosion off the field.”
Krosch crops all his sediment-control dams, including a large, L-shaped dam in another field that’s about 6 ft. high. “I’ve never had a problem farming around them,” he says. “When the rest of the field has been ready to work, the basins have been, too.”
One year, he did have some crop loss when an intake pipe got plugged up with residue and failed to drain properly. Another time, water overtopped one of the berms, damaging it.
WASCOBs don’t stop sheet and rill erosion, so at least 30% residue cover is needed to reduce sediment loading in the basin, Hellermann says. Krosch, who farms very heavy clay loam soils, also suggests installing some subsurface tile at the top of the drainage-way to cut surface flow volume and extend the life of the WASCOB. Eventually, the ponding area fills up with sediment and has to be scraped out.