Now is a good time to evaluate and perform maintenance on terraces on wheat stubble or fallow ground, said DeAnn Presley, K-State Research and Extension soil management specialist.
In Kansas, more than 9 million acres of land are protected by more than 290,000 miles of terraces, making Kansas No. 2 in the U.S. for this soil and water conservation practice. To accomplish their purpose for erosion control and to save water, terraces must have adequate capacity, ridge height and channel width, Presley said.
“Without adequate capacity to carry water, terraces will be overtopped by runoff in a heavy storm. Overtopping causes erosion of the terrace ridge, terrace back slope, and lower terraces—and may result in severe gullies,” she said.
Terraces need regular maintenance to function for a long life. Erosion by water, wind, and tillage wears the ridge down and deposits sediment in the channel, decreasing the effective ridge height and channel capacity. They can also be damaged by machinery, animals and settling.
“Terrace maintenance restores capacity by removing sediment from the channel and rebuilding ridge height,” Presley said.
“Check terraces and terrace outlets regularly, at least annually, for needed repairs. The best time to check is after rains, when erosion, sedimentation, and unevenness in elevation are easiest to spot. Specific items to note are overtopping, low or narrow terrace ridges, water ponding in the channel, terrace outlets, erosion, and sediment clogging near waterway or pipe outlets,” Presley noted.
Terrace maintenance can be done with virtually any equipment that efficiently moves soil, she said. Common tools include those that:
- Turn soil laterally -- moldboard plow, disk plow, one-way, terracing blade (pull-type grader), three-point ridging disk (terracing disk, etc);
- Convey or throw soil (belt terracer, scraper, whirlwind terracer, etc); and
- Push or drag soil (dozer blade, straight-wheeled blade, 3-point blade, etc).
If silt bars and sediment deposits accumulate frequently in a terrace channel, excessive erosion is the cause, Presley said. A change in tillage and cropping practices is needed to correct that problem.
“In this situation, conservation tillage and crop rotations that retain crop residue will reduce erosion substantially. This will reduce the frequency of terrace maintenance needed. Many no-till producers find terrace systems require little maintenance. Although runoff still occurs, there is very little soil movement in a no-till system,” she said
For more information, including specific information on maintenance practices, refer to K-State Research and Extension publication C-709, Terrace Maintenance, available at county and district extension offices, or online at: http://www.ksre.ksu.edu/library/ageng2/c709.pdf.
Additional sources for technical information include local USDA-Natural Resources Conservation Service and County Conservation District offices.