Ephemeral gullies are those small gullies that appear in fields because water runs down certain slopes every season. Conventional-tillage farmers barely notice them because they smooth them out with tillage. But the gullies reappear later.
No one knows exactly how much soil is lost to ephemeral gully erosion because erosion measurements include sheet erosion, which occurs over entire fields. But researchers are beginning to provide the answer.
The research uses a computer model with historical precipitation data, on-site observations and new watershed-modeling technology. It evaluates how tillage practices affect the formation and evolution of ephemeral gullies and subsequent erosion rates.
On three fields in the U.S. and one in Europe, the model revealed that ephemeral gully erosion accounted for 2.2 tons to 4.9 tons of soil per acre per year with conventional tillage and 0.9 tons to 1.8 tons per acre per year with no-till.
Although no-till doesn't always eliminate ephemeral gullies, it greatly reduces the problem, says one of the researchers, agricultural engineer Ronald Bingner of the USDA–
Agricultural Research Service (ARS) National Sedimentation Laboratory in Oxford, Miss. In contrast, tillage loosens soil, destroys structure and removes surface cover, making it easier for the gullies to "migrate” upward through a field.
The model will be applied to more fields to find the best methods of eliminating ephemeral gullies.
Other scientists who helped develop the model came from USDA–ARS, the University at Buffalo (part of the State University of New York system) and the Natural Resources Conservation Service.
Look Before You Leap
Before you install a small wind turbine to reduce farm energy cost, do your homework, advises Purdue University renewable energy specialist Chad Martin. Start by determining the real efficiency of energy-consuming sys-tems in your operation.
If your turbine doesn't run often enough, it will be a bad investment. Learn the wind speed for your locality at http://navigator.awstruewind.com. The U.S. Department of Energy provides maps showing wind power potential at www.eere.energy.gov/windandhydro/windpoweringamerica.
You can investigate sources of fund-ing assistance for renewable energy products, available through the 2008 farm act's Renewable Energy for America Program, at www.rurdev.usda.gov. A Purdue Extension pub-lication, "Energy from the Wind: Planning for a Small Wind Turbine in Rural Areas of Indiana,” contains useful information regardless of what state you farm in. It's available at www.ces.purdue.edu/bioenergy
- November 2008