|VAN KEUREN, ROBERT|
Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/1996
Publication Date: N/A
Interpretive Summary: Grasslands used for cattle grazing is an important land use for many areas of the United States. Various aspects of cattle impacting western rangelands have received attention. However, very little emphasis has been placed on how grazing livestock influence surface runoff and sediment loss from pastures in the eastern U.S. Different pasturing systems have been studied in eastern Ohio for 20 years to study runoff and erosion. In one of the systems, a field has been rotationally grazed during the growing season and used as a feeding area during the winter, dormant season. During 12 years of this management, over 10% of the rainfall ran off the surface. During the years before and after this management when there was summer only or no grazing, less than 3% of the rainfall ran off. Sediment losses during the above 12 year period annually averaged over one ton per acre contrasted with 130 lbs per acre each year during summer only grazing. This study indicates that year after year winter feeding of cattle on the same pasture field is not a good practice, but rotational grazing of cattle on pastures in the eastern U.S. creates few problems with regards to surface runoff and erosion.
Technical Abstract: Grazing is an important land use in the humid, eastern US. When the grass is dormant, late fall through early spring, the land is most vulnerable to the pressures of livestock. Dormant period management practices include: no animal occupancy, low animal density with supplemental feeding, high animal density with feeding, and grazing of late-summer regrowth and feeding. Runoff and sediment losses from a small pastured watershed (WS) in eastern Ohio have been studied for 20 years. A beef cow herd grazed it rotationally during the growing season for 12 years and was fed hay in this WS during the dormant season (high animal density with feeding), Period 1. During the next 3 years of this study, Period 2, there was summer rotational grazing only. There was no animal occupancy on this WS during the last 5 years, Period 3. Annual runoff during Period 1 (120 mm) was over 10 percent of precipitation and less than 2 percent during Periods 2 and 3 (14 and 6 mm, respectively). The decrease in annual sediment loss was even greater with the change in management; 2259, 146, and 9 kg/ha for the three periods respectively. Over 60 percent of the soil loss during Period 1 occurred during the dormant season. In response to weather inputs, there was considerable seasonal and annual variation in runoff and soil loss within management periods. When the management was changed, the impacts of the previous treatment were not long lasting, changing within a year.