Grass Hedges Do Protect Water

Research shows sedimentary runoff can be greatly reduced by grass hedges.

Published on: Nov 26, 2009

Planting grass hedges could be the answer to successfully bringing some Conservation Reserve Program land back into production. Researchers at the Agricultural Research Service have found that grass hedges can help farmers preserve soil and protect water quality by trapping sediment that would otherwise be washed away by field runoff. Their findings are based on a series of studies conducted 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% slope. 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. The hedges captured approximately 90% of eroded sediment from ultra-narrow-row conventionally tilled fields, and only about 50% of sediment from no-till fields.

 

The team also found that hedge effectiveness was enhanced when clippings were allowed to accumulate uphill of the hedges. But even if all the clippings from grass hedges over 1.5 feet tall are removed for livestock feed or bioenergy production, the hedges can still help protect against field erosion.