Wednesday, January 28, 2009

Growth Spurts: Grass Strips Curb Erosion, Block Herbicide Runoff

Grass filter strips placed in riparian zones not only curb soil erosion, but also block and degrade the widely used herbicide atrazine, Agricultural Research Service (ARS) scientists report.

Atrazine has been used extensively to suppress weeds in corn production for decades, but because it's applied directly to soil it's especially prone to losses in surface runoff. The contamination of surface water by atrazine and its less-toxic breakdown components has raised ecological concerns.

Riparian zones are transitional areas between upland areas, such as crop fields, and water bodies. The grasses and other vegetation in these zones help reduce pollution in streams and lakes.

In studies of the effect of different grass species on herbicide transport and degradation, eastern gammagrass showed the highest capacity for promoting atrazine degradation. Orchardgrass, smooth bromegrass, and switchgrass were also effective.

The studies have shown that grass buffers reduced the transport of herbicides to shallow groundwater and in runoff. These buffers can reduce herbicide transport through trapping of sediment and by increased infiltration of water into the soil.

Source: Agricultural Research Service, USDA

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