User talk:Lzhenderson

=Vegetative Filter Strips=

Vegetative Filter Strips are widely used as one of the best management practices (BMP’s) to help mitigate and control the loss of sediment from runoff from agricultural, forested, urban, and pasture/rangelands and to reduce the pollution of water systems from various forms of contaminants. Filter strips and buffer strips have been used interchangeably but filter strips are the preferred term since it is a designated area of natural or planted vegetation that lies between an area of potential pollution and a surface body of water that filters sediment and organic matter, excess nutrients, chemicals, and metals present in the sediment or dissolved in water. In some cases filter strips can be used as a means of controlled livestock grazing if kept away from streams or reservoirs, and can actually increase the safety of agricultural operations by keeping moving machinery away from steep stream banks and saturated ditches.

Filter Strip Performance
The accuracy of the predicted improvement from the installation of a vegetative filter strip is often delayed by the limited amounts of quantitative data that determines the performance of the design factors of this type of land use implementation. Factors that effect performance include vegetative composition and density, width, and the types of contaminants or pollutants the filter strips are employed to mitigate.

Filter Strips and Water Quality
The impacts of vegetative filter strips (VFS) are dependant of the type of contaminant to be controlled. Several comparisons show that sediment is greatly retained in grasses more so than soluble nutrients and chemicals. Differences in impacts on diverse contaminants are credited to certain mechanisms of the filter strips that include settling, infiltration, and dilution. Particulate settling removes sediment and sediment bound contaminants from runoff outflow. Infiltration from runoff caries dissolved contaminants thereby removing their mass in outflow. Dilution of runoff by rainfall reduces concentrations of contaminants.

Contaminants such as organic solvents, PCBs, heavy metals, polyaromatic hydrocarbons, explosives and energetics, or nutrients can be removed, contained, or rendered harmless by the process of phytoremediation. This type of technology is another form of using plants to filter out contaminants from the soil. The key processes of phytoremediation include stimulation of micro-organisms, slowing of contaminant transport, and plant uptake followed by metabolism or accumulation.

Application
Filter strip application should take into consideration the type and quantity of the potential contaminants such as sediments, nutrients, pesticides, organic matter, metals, or other pollutants. Soil characteristics such as the amount of clay and organic matter present, the infiltration rate, permeability, and structure are key elements to consider as well. Site characteristics, such as slope length and gradient, position of site, aspect and terrain shape, surface runoff potential, and area of the field to be flowing into the filter should be determined. The type of vegetation required for effective control of contaminants should be applicable to the climatic conditions in your area, and time of year/length of growing season to properly establish that vegetation.

Width
The NRCS and state and federal agencies have determined general rules for the determination of the effective width of a filter strip. Generally, wider widths, gentler slopes, and denser vegetation decrease the risk of sediment and contaminant delivery to water systems by runoff. However, vegetative characteristics such as increased biomass, cover, and density are more important than stubble height for better control of contaminants from overland flow. Recommended minimum widths should be adjusted upward if the sediment entering the filter has a higher percentage of clay, which takes a longer distance to filter out contaminants as compared to silt- and sand-sized particles. Also, for slopes with a gradient steeper than 10 percent, there is an increased potential for the volume and velocity of the runoff to flow too fast through the filter and possibly lay over the vegetation and severely reducing its effectiveness.

Individual states develop guidelines to protect and manage for widths of filter strips and forest riparian areas. Most common recommendations for riparian management zone are 50 feet or wider, however, 25 feet or more is recommended for filter strips on slopes 20-40 percent. Knowledge of site-specific conditions is crucial to the effective implementation of filter strips.

Installation
Land grading or other soil surface preparations may be necessary to ensure that the filter will function properly and that runoff will enter the filter in the form of shallow, uniform flow. Once the type of vegetation is selected, soil fertility should be evaluated, and the type of seeding method selected. The amount of fertilizer and lime to be applied to the filter should be determined from a soil analysis taken from the area. Two types of tillage systems are normally used when seeding filter strips: conventional or no-till seeding. The recommended steps for conventional seeding of a filter strip are: •	Broadcast lime and fertilizer according to soil test recommendations. •	Incorporate lime and fertilizer with a disk or field cultivator. •	Prepare a firm seedbed (use of a cultipacker or cultimulcher is a good choice). •	Plant the seed shallow (1/4 inch deep) with a drill, cultipacker seeder or by broadcasting the seed; follow by cultipacking, making sure the seed is on a firm seed bed to obtain good contact with the soil.

Maintenance
Proper maintenance is required to obtain maximum filter-strip effectiveness and maintenance for grass and legume filters consists of several simple steps: I.	Inspect the filter strip frequently, especially after intense rainfall or runoff events. II. Minimize the development of erosion channels within the filter. III. Reseed or over seed bare areas of the filter, the use of mulch or sod may be necessary. IV. Mow and remove hay as required or as allowed by certain USDA programs to maintain moderate vegetation height and wildlife habitat. Mowing two to three times per year may be necessary and should not be mowed closer than 6 inches. V.	Soil test periodically and apply soil amendments according to test results. VI. Control trees, brush, noxious weeds, and Canada thistle in the filter using either mechanical methods or with herbicides, except near riparian zones.

Long Term Effective Management
Certain specifications and recommendations should be incorporated into VFS cost-sharing programs. The VFS site suitability should be determined by trained personnel and the vegetation and seeding rates should be applied appropriately for local soil and climatic conditions, and approved for use in the designated area to promote good vegetative growth, nutrient removal, and filtering ability. The VFS should be mowed and the residue harvested at least 2-3 times per year; and before payment of cost-sharing funds are approved, and once each year thereafter, the VFS should be inspected by a conservation or pollution control official to ensure that the VFS meets minimum standards.

Reference:
-Filter Strip Performance and Processes for Different Vegetation, Widths, and Contaminants, T.J. Schmitt, M.G. Dosskey, K.D. Hoagland -Journal of Environmental Quality, Sediment Retention in Rangeland Riparian Buffers, 2003 May-Jun; 32(3):1130-7. Hook, P.B., Dept. of Land Resources and Environmental Sciences, Montana State University-Bozeman. -Journal of Forestry, Riparian Management Practices: A Summary of State Guidelines, Volume 99, Number 8, 1 August 2001, pp. 11-17(7). Blinn, C.R., Kilgore, M.A. -Points of Contact for Phytoremediation Research, Elly P.H. Best, Richard A. Price, U.S. Army Corps of Engineers - Vegetative Filter Strips: Application, Installation and Maintenance, Ohio State University Enxtension, AEX-467-94. Rob Leeds, Larry C. Brown, Marc R. Sulc, Larry VanLieshout - Water Environment and Technology, Long-term Effectiveness of Vegetative Filter Strips, Vol. 1, No. 3, p 419-421, November 1989. Dillaha, T.A., Sherrard, J.H., Lee, D.