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Home > AFO Strategies for Source Water Protection > Reactive Solutions for Managing and Treating AFO Wastes

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Vegetative Filter Strips

NRCS Buffer Strips: Common Sense Conservation - good website with information about buffer strips and links for more detailed reports and guidance
NRCS Economics of Conservation Buffers - web page with links to information sources on buffer economics
Evaluation of Riparian Buffers and Controlled Drainage - summary of a North Carolina State University research project

Summary:

Vegetative filter strips (also called riparian buffers or vegetative buffer strips) are a type of BMP designed to trap and reduce sediment, nutrients (nitrogen and phosphorus), and microbial contaminants in stormwater runoff. This is one of the most common BMPs employed (along with fencing cattle out of streams), though some question their effectiveness, especially in saturated soils and in the winter (Wright and Gooch, 2005). Vegetative filter strips consist of bands or areas of planted or indigenous vegetation located between a waste source and downgradient receiving water. They can remove pollutants via filtration, deposition, infiltration, absorption, volatilization, plant uptake, and decomposition (Harner and Kalita, 1999). Near surface vegetation can increase soil organic content and local microbial populations, enhance porosity and soil permeability, slow down near surface flow velocities, and provide more organic-rich surfaces for adsorption.

Field experiments show that vegetative buffer strips can significantly reduce nutrients and fecal coliforms from feedlot runoff (Keaton et al., 1998; Kalita and Harner, 1998; Williamson et al., 1999). Research on the ability of vegetative buffer strips to remove Cryptosporidium parvum oocysts during surface and shallow subsurface flow demonstrated 1 to 3-log removal by filter strips under simulated rainfall conditions (Atwill et al., 2002). Vegetative filter strips can be effective at removing Cryptosporidium oocysts from surface runoff, however, viruses (PRD1 bacteriophage) and to a lesser extent bacteria (E. coli) are more easily transported (CRC, 2004). Laboratory experiments have shown that a one-meter width (i.e., about three feet) of grass vegetation could reduce Cryptosporidium in surface water runoff by up to 99.99 percent compared to bare soil alone (CRC, 2004).