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Title: IMPACT OF GROUND COVER ON RUNOFF AND EXPORT OF NUTRIENTS AND SEDIMENT FROM RIPARIAN PASTURE

Author
item BUTLER, D - NC STATE UNIVERSITY
item RANELLS, N - NC STATE UNIVERSITY
item GREEN, J - NC STATE UNIVERSITY
item Franklin, Dorcas
item POORT, M - NC STATE UNIVERSITY

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/2/2004
Publication Date: 6/12/2004
Citation: Butler, D.M., Ranells, N.N., Green, J.T., Franklin, D.H., Poort, M.H. 2004. Impact of ground cover on runoff and export of nutrients and sediment from riparian pasture. Proceedings of the American Forage and Grassland Conference, June 12-16, 2004, Roanoke, Virginia. p. 524.

Interpretive Summary: Many farms in the Southeastern USA have small herds of livestock (< 30 brood cows). In North Carolina, 1.7 million acres of pastureland have small herds that often utilize streams as a watering source. In the past few years, significant emphasis has been placed on riparian areas in voluntary and mandatory programs through general basinwide management plans as well as farm-scale nutrient management plans. As farmers and agricultural agency professionals are asked to manage for improved water quality, research based options must be available for on-farm implementation. The objective of this work was to determine the effects of ground cover on nutrient and sediment export from pastured riparian areas. ARS scientists at J. Phil Campbell Sr. Natural Resource Conservation Center, Watkinsville, GA in cooperation with N. Carolina State Univ., Raleigh, NC used rainfall simulators to evaluate runoff from riparian pasture plots with applied cattle feces and urine in May, June, Sept., and Oct. 2003. Plots were established on 10% and 20% slopes of existing stands of tall fescue (Festuca arundinacea Schreb.) / dallisgrass (Paspalum dilatatum Poir.) with stands modified to represent ground cover levels at 0%, 45%, 70%, and 95%. In addition, wetland vegetation plots with ground cover levels of 0% and 95% on an approximate slope of 10% were used in this study. Data on runoff volume, total suspended sediments (TSS), and nutrients were examined. Preliminary data analysis of tall fescue-dallisgrass vegetation at 20% slope and 0% ground cover indicated greater runoff ( =0.1 level) compared to plots with 70% and 95% ground cover. On 10% slopes, the 0% cover treatment had greater runoff than plots with 45%, 70%, and 95% cover. This suggests that steeper slopes may require more vegetative cover to reduce runoff volumes. State Cooperative Extension Systems and USDA-NRCS personnel may utilize this information in the development of voluntary and mandatory management plans.

Technical Abstract: In North Carolina alone, 1.7 million acres of pastureland have small herds that often utilize streams as a watering source. As farmers and agricultural agency professionals are asked to manage for improved water quality, research based options must be available for on-farm implementation. The objective of this work was to determine the effects of ground cover on nutrient and sediment export from pastured riparian areas. Rainfall simulators were used to evaluate runoff from riparian pasture plots with applied cattle feces and urine in May, June, Sept., and Oct. 2003. Plots were established on 10% and 20% slopes of existing stands of tall fescue (Festuca arundinacea Schreb.) / dallisgrass (Paspalum dilatatum Poir.) with stands modified to represent ground cover levels at 0%, 45%, 70%, and 95%. Data on runoff volume, total suspended sediments (TSS), total Kjeldahl nitrogen (TKN), nitrate (NO3-N), ammonium (NH4-N), total Kjeldahl phosphorus (TKP), and dissolved reactive phosphorus (DRP) in surface runoff were examined. Preliminary data analysis of tall fescue-dallisgrass vegetation at 20% slope and 0% ground cover indicated greater runoff ( =0.1 level) compared to plots with 70% and 95% ground cover. On 10% slopes, the 0% cover treatment had greater runoff than plots with 45%, 70%, and 95% cover. This suggests that steeper slopes may require more vegetative cover to reduce runoff volumes.