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Summer 2013 ARDF Bulletin 4 Gully Formation, Prevention and Repair Neal Mays ullies can form in pastureland over • Gully sides: active gullies tend to have a short time but more commonly vertical sides; when healing, sides Gerode over a period of years. slough away and begin to support Natural drainages devoid of vegetation growth of vegetation. erode as runoff water cuts into the chan- • Gully depth commonly increas-es in nel. The problem may be exacerbated actively eroding gullies. by cattle paths crossing the drainage, if the drainage is a preferred loafing area for the herd, or if the area is exposed to Gully Formation vehicle traffic. Further, gullies may carry significant sediment loads in storm events, Gullies form for two reasons: and without vegetative cover impeding water flow, they may quickly form gulches 1. Increased runoff within a channel across fields or natural landscapes. Gully 2. Inability of a channel to carry runoff repair is expensive and labor intensive. As water without degrading the channel the old saying goes, “An ounce of preven- boundaries tion is worth a pound of cure.” • Channel capacity is influenced by its shape, cross-sectional area, gradient, Classes of Gullies and roughness. Gullies may be broadly divided into two • Excavation within drainage channels classes: may alter one or more of these factors determining channel capacity. Excava- • Crossable, meaning farm equipment tion or tillage within channels, which can be safely driven over the gully; removes or displaces soil, or removes these gullies may be repaired with ordi- root systems of grass and/or woody nary cultivation OR species within the channel, greatly • Uncrossable, meaning not repairable increases the likelihood of gully with ordinary cultivation implements development. • Overgrazing and de-vegetation is a Arkansas Discovery leading cause of gully development in Parts of a Gully Farms Program pastures. Removal of vegetation Department of • Gully head: the portion of the gully decreases surface roughness and may Crop, Soil, and increase water velocity enough to Environmental Sciences furthest up the slope. Active gully begin cutting a gully into the channel. 115 Plant Sciences Bldg. heads move up the slope a bit further University of Arkansas with each erosive storm. Taking Similar erosive action may occur after Fayetteville, AR 72701 photographs can help gauge the extent fires. Phone: (479) 575-2354 of erosion each year. Fax: (479) 575-3623 Gullied land does not readily sup- port plant growth. Gaining control of erosive forces in active gullies requires planning and perseverance. Photo courtesy of USDA-NRCS.

Gully Prevention Vegetative Gully Repair and Control 1. Awareness: Recognize natural drainage ways as Gully repair can be a large and costly job, in some sensitive areas which need protection. cases perhaps exceeding the value of the affected land. However, it has been said regarding gully control, 2. Observation: Look for signs of instability in a drain- a bag of fertilizer is more effective than a bag of age area. This may include natural de-vegetation cement. Slowing or completely stopping gully devel- such as a tree uprooting and exposing soil, livestock opment by establishing new vegetation is one of the paths, or roads which expose bare soil. least expensive approaches and commonly the most 3. Action: If no gully formation has occurred, con- aesthetically appealing. tinue to manage so it doesn’t begin. The Natural Resources Conservation Service provides • Pay attention to stocking density. potential financial incentives for practices to prevent gully erosion through programs such as the Environ- • Utilize fencing to keep stock off sensitive area until mental Quality Incentive Program (i.e. EQIP). One it has healed and re-vegetated. Electric fences are such practice is establishment of grassed waterways easy to install and effective for controlling livestock (CP 412), which is defined as a shaped or graded when properly constructed and maintained. channel established with suitable vegetation and • Be proactive while damage is minimal. Re-vegetate designed to carry surface water at a non-erosive using appropriate species. This may include grasses, velocity to a stable outlet. shrubs, or trees — or a mix of all these. 1. Plant Selection:

• If gully erosion is occurring, land use has exceeded • Native plants that grow well in poor soil may be a the ability of the channel to remain at equilibrium good choice because of harsh conditions found in and adequately carry the required flow. gullies. Exposed soil in gullies is typically low in nutrients and organic matter and may be primarily sand or clay. • Careful attention should be given to using non- native species

2 Thick stands of grass, shrubs, or trees provide stability to the sides and floor of channels. Their roots bind soil and protect against erosion. Channels must remain covered with vegetation to prevent degradation. Photo by Lynn Betts, USDA Natural Resources Conservation Service.

Gully formation may be prevented relatively inexpensively using materials found on the farm. Here, rock is used at the end of a grassed waterway to slow water movement and prevent erosion. Funding incentives for similar structures are sometimes available through USDA- NRCS’s cost sharing program (EQIP). Photo by Glynn Beck, Kentucky Geological Survey.

•A spreading or creeping growth habit is best. Structures for Repairing Severely Eroded Gullies Growth by runners (e.g. bermuda grass, persim- mon) or ability to sprout new plants from roots USDA and other government agencies have prepared (e.g. black locust) may improve ability to cover guidelines for effective gully repair and control. See the affected area. the following links: • Planting a range of species may be advisable to • https://engineering.purdue.edu/~abe325/RE- determine which are the best choice for gully SOURCES/Low-Cost%20Gully%20Erosion.pdf reclamation. • http://www.omafra.gov.on.ca/english/engineer/ 2. Planting Methods: facts/88-059.htm • http://www.forestry.ok.gov/Websites/forestry/ • In woody species, better success may be had using established seedlings rather than seed. Images/documents/WaterQuality/Forestry%20 Note,%20Side%20Gully%20Control%20Fact%20 • Soil testing should be included in reclamation plan- Sheet.pdf ning. Correct nutrition improves seedling survival and vigor.

• Protect established vegetation from damage until it is well-established. This may take several years. For more information, contact your local County Extension Office or your • Starting plants in good soil in burlap sacks, paper local USDA Service Center. livestock feed sacks, or even cotton cloth (such as old tube socks), then planting in the gully will help prevent wash away during the first few rains, and roots will grow through the containers as they rot. To protect or introduce grass seed on sides of a gully, mulching with hay may be helpful. 3