Are Livestock Grazing and Healthy Streams Compatible? Livestock Grazing Systems that Reduce Erosion and Improve Stream Bank Stability

View the project final report

Commodities

• Agronomic: corn, soybeans
• Animals: bovine

Practices

• Animal Production: grazing - continuous
• Crop Production: agroforestry, forestry
• Education and Training: demonstration, farmer to farmer, on-farm/ranch research, workshop
• Natural Resources/Environment: riparian buffers, riverbank protection, soil stabilization
• Soil Management: soil quality/health

Soil and phosphorus losses from stream bank erosion among different land-use practices were compared in three Iowa regions. Stream bank erosion was measured with erosion pins (estimate erosion rate), and by surveying the severe and very severe eroding banks of all treatments. Soil samples from the stream bank face were collected to estimate bulk density and soil total phosphorus. Row-cropped fields and continuous pastures had the highest soil and phosphorus losses, while riparian forest buffers, grass filters and pastures with cattle completely excluded from the stream the lowest. Erosion rates of individual banks did not differ between grazing practices or between buffers and pastures with cattle excluded from the channel. The differences in soil and phosphorus losses between practices were the result of percentages of the total bank lengths that were eroding within each practice. Intensive rotational pastures showed some indications of reducing soil and phosphorus losses from bank erosion compared to continuous pastures. Total eroding lengths varied from about 11% for the buffered and cattle excluded streams to 27% for the intensive rotational and 38% for the continuously grazed pastures. These losses translate to 4 to 7 tons km-1 yr-1 to 155 to 235 tons km-1 yr-1 for the two sets of practices.

The overall goal of this project was to collect and present data to convince farmers who continuously graze livestock in riparian corridors to adopt rotational and intensive rotational grazing practices because of environmental and monetary benefits.

The goal would be accomplished by conducting research on the environmental benefits of rotational and intensive rotational grazing and by education/training.

The specific research objective of this project was to compare the impact of different grazing practices and other agricultural practices on stream bank erosion and phosphorus movement. Bank erosion rates along continuous, rotational, and intensive rotational pastures were compared to bank erosion rates along riparian forest buffers and grass filters, pastures with cattle fenced out of the stream, and row-cropping adjacent to the streams.

The hypothesized order from highest to lowest stream bank erosion was: row-cropped fields adjacent to streams, continuous pastures, rotational pastures, intensive rotational pastures, pastures with the stream excluded to cattle, grass filters, and riparian forest buffers.