Sunday, August 30, 2009

Erosion control with hedges

Ann Perry at the US Department of Agriculture website: One way farmers can preserve soil and protect water quality is by planting grass hedges to trap sediment that would otherwise be washed away by field runoff. Agricultural Research Service (ARS) scientists at the agency’s National Sedimentation Laboratory in Oxford, Miss., have calculated how much soil erosion these hedges prevent and verified predictions of the Revised Universal Soil Loss Equation version 2 (RUSLE2).

Agronomist Seth Dabney, hydrologist Glenn Wilson and agricultural engineer Robert Cullum collaborated with retired agricultural engineer Keith McGregor in a series of studies over 13 years to assess the effectiveness of grass hedges for erosion control in wide or ultra-narrow-row conventional tillage or no-till cotton systems.

The researchers established single-row continuous swaths of miscanthus, a tall perennial grass, across the lower ends of 72-foot-long plots with a 5 percent slope. Then they tracked how much sediment was trapped by the vegetation from both the wide and ultra-narrow-row conventional tillage and no-till fields. The hedges eventually became a yard wide and were clipped two to three times every year after the grass was 5 to 6.5 feet tall.

The scientists found that the ability of the hedges to trap sediment increased as the hedges matured. The hedges were more effective at intercepting sediments that washed out of conventionally tilled fields, possibly because the eroded materials from no-till fields were composed of smaller particles….

A hedge of miscanthus grass, from the USDA website, shot by Seth Dabney of the Agricultural Research Service

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