June 4, 2008
Once properly established, grassed waterways may provide excellent control of
rill and ephemeral gully erosion. But unless properly maintained, especially
at planting time and after heavy rains, costly damage can greatly impact how
well grassed waterways prevent soil loss.
Due to delayed planting and recent heavy rains in many areas of the state,
now is a good time to perform grassed waterway maintenance checks, according
to Angela Biggs, district conservationist with the USDA-Natural Resources
Conservation Service (NRCS) in Shelby County. “In fact a poorly maintained
grassed waterway can actually contribute to a farmer’s erosion problems, not
prevent them,” she said.
Grassed waterways are typically broad, shallow channels designed to move
surface water across farmland while minimizing the risk of soil erosion. The
vegetative cover in the waterway slows the water flow and protects the soil
surface from erosion. They are often constructed in natural depressions where
the water collects and flows to an outlet.
Even when grassed waterways are well-established, NRCS recommends producers
should avoid some activities to keep the waterways working well. According to
Biggs, some of these activities include:
- Lift implements out of the ground before driving across the practice.
- Avoiding planting end parallel to the water flow path of the grassed
waterway.
- Avoiding spraying herbicides in the waterway.
- Avoiding driving up and down grassed waterways, especially during wet
conditions. Ruts caused by tire tracks can lead to gullies.
Other keys to maintaining effective grassed waterways include:
- Inspect the grassed waterway, especially after heavy rains, for eroding
areas and places needing reseeding.
- Repairing rills or gullies by reshaping and reseeding.
- Maintaining the width of the grass area when tilling and planting.
- Maintaining outlets to prevent gullies. This may include reshaping and
reseeding the outlet, or repairing components of structural outlets.
Stanley Christensen, a farmer from Harlan, first installed his grassed
waterway in 2004. It still protects his field from a troublesome ditch because
he properly maintains it.
According to Christensen a ditch formed in his field that was continually
eroding throughout the years. “We’ve farmed since 1963, so we’ve had 41 years
of experience dealing with this ditch and had never been able to control it,”
he said. “Since we did the grassed waterway, we’ve never had to worry about
it.”
NRCS helped Christensen create a 40-foot-wide grassed waterway with tile
lines on each side and a coconut fiber blanket to help prevent soil erosion
until the grass established, he said. On steeper slopes, where gullies need
filling during construction and the land owner was not previously able to
establish the grass, a lined waterway may be warranted, according to Biggs.
In addition to technical assistance, NRCS provides financial assistance for
installing grassed waterways through the Environmental Quality Incentives
Program (EQIP). Other financial assistance is also available from the Iowa
Department of Agriculture and Land Stewardship-Division of Soil Conservation
and the Continuous Conservation Reserve Program, administered by the Farm
Service Agency.
According to Christensen the ditch was a real eyesore. “We are just
extremely happy with the waterway. We did it for the economic benefit of
farming the area and for the conservation part to eliminate the soil erosion.
The grassed waterway is a beautiful addition to the farm,” he said.
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