|Haan, Mathew - IOWA STATE UNIVERSITY|
|Russell, James - IOWA STATE UNIVERSITY|
|Nellesen, Shelly - IOWA STATE UNIVERSITY|
Submitted to: American Forage and Grassland Council Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 26, 2007
Publication Date: June 26, 2007
Citation: Haan, M.M., Russell, J.R., Kovar, J.L., Nellesen, S.L. 2007. Effects of grazing management on stream bank erosion [abstract]. American Forage and Grassland Council Conference Proceedings. 16:18. Technical Abstract: Cattle grazing in riparian areas may contribute to sediment and nutrient loading of surface waters. A project was conducted to establish the effects of cattle grazing on stream bank erosion. Six 30-acre cool-season grass pastures, each bisected by a 642-foot stream segment, were assigned one of three treatments: continuous stocking with unrestricted stream access (CSU), continuous stocking with restricted stream access (CSR), and rotational stocking (RS). Each pasture was stocked with 15 fall-calving Angus cows from May through October 2005 (1430 lbs) and 2006 (1271 lbs). Stream bank condition score and stream channel morphology were determined pre-, mid-, and post-grazing in both years. Stream bank erosion was measured with erosion pins placed in ten transects per pasture. The exposed pin length was measured monthly during the grazing season, and one month post-grazing in both years. At one location per pasture, bank erosion was also measured with ground-based LiDAR pre- and post-grazing in 2006. Stream banks in CSU pastures had a greater (P<0.05) condition score than did CSR or RS pastures, indicating greater susceptibility to erosion. Stream cross-sectional area and bank width increased at a rate of 0.075 ft2 per day and 0.008 ft per day, respectively, with no difference among grazing treatments. Net erosion, as determined by erosion pins, averaged -2.1 (erosion) and 0.04 (deposition) inches in 2005 and 2006, respectively, and was not affected by treatment in either year. During the entire study period (May 2005 through November 2006), the rate of soil erosion from stream banks averaged 0.003 inches of soil per day and did not differ among treatments. LiDAR scan data showed a slight net deposition of sediment across all treatments in 2006. Grazing management had little effect on stream bank erosion during the study period.