Description and Benefits
A filter strip is an area of grass or other permanent vegetation used to “filter” sediment, organics, nutrients, pesticides, and other contaminants from farm sheet flow runoff in order to maintain or improve water quality in local water bodies, such as streams and ponds. Filter strips slow the velocity of water, allowing the settling out of suspended soil particles, infiltration of runoff and soluble pollutants, adsorption of pollutants on soil and plant surfaces, and plant uptake of soluble pollutants. Filter strips are typically no narrower than twelve feet, and increased width typically increases the filtering or water quality benefit. Filter strips can be an aesthetic means of stabilizing field border soil and can also serve as forage (on-farm use or cash crop), turnrows and headlands, and field access. Filter strips can enhance wildlife objectives depending on the vegetative species used and management practiced. When planted with native or adapted vegetative species they can provide food and cover for important wildlife.
When to use Vegetated Filter Strips
Filter strips are most effective and useful on land with less than 10% slope at the lower edge of crop fields, sacrifice areas, or hardened footing areas where there is sheet or uniform shallow flow, especially adjacent to streams, ponds, lakes, and drainageways. They can also serve as part of a riparian forest buffer system or as part of an agricultural waste management system. The filter strip should be designed to accommodate anticipated flows, slope and soil type to maximize the potential benefit.
