N.C. STATE UNIVERSITY

College of Agriculture and Life Sciences
N.C. Agricultural Research Service
N.C. Cooperative Extension Service

Water Quality Improvement by Planted and Riparian Buffers

Prepared by: J.W. Gilliam, J.E. Parsons, R.L. Mikkelsen

Objectives:

1. To determine the long term effectiveness of vegetated filters for the removal of sediments, nutrients (primarily N & P) and bacteria from agricultural runoff water including areas receiving animal waste.

2. To determine if plant type (grass or trees) influences the effectiveness of the filters.

3. To utilize data obtained in objective 1 to test and modify existing models to (1) simulate overland flow and sediment transport) and to (2) simulate the fate of sediment, nitrogen and phosphorus.

Accomplishments

1. Natural riparian buffers between agricultural fields and small streams have been found to reduce nitrate in subsurface flows by 90% before the water enters the surface water.

2. Planted and natural riparian buffers between fields and surface waters can reduce phosphorus in surface runoff by approximately 50% and sediment loads by over 90%.

3. Because of their presence on most NC streams, natural riparian buffers are the single most important factor controlling nonpoint source pollution of NC surface waters.

The work in NC showing the effect of riparian buffers on removal of sediment and nutrients from agricultural drainage waters was among the first in the world. Because of the work here and two other locations, riparian buffers are now required in two states and by many cities. Many other states including NC are currently recommending riparian buffers and regulations are possible regulations are being considered. We were invited to testify before the U.S. Senate Agricultural Committee on effectiveness of riparian buffers as related to regulations in the Conservation Reserve Program in the 95 Farm Bill. It now appears that the Farm Bill will place a premium upon leaving natural areas adjacent to streams. Utilization of natural and planted vegetated buffers are an inexpensive, effective and popular method of preventing contaminants in runoff from agricultural fields from reaching streams and lakes.

Future Plans

Future work will concentrate upon utilization of a combination of planted and natural riparian buffers in conjunction with wetlands to minimize movement of contaminants from land receiving animal waste to streams. Efforts will be made understand the processes controlling the movement and to develop models predicting movement under a variety of conditions.