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Vegetative Filter Strips to Reduce Pathogens and Nutrients in Runoff from Livestock Feedlots

Prasanta Kalita
Assistant Professor
Department of Agricultural Engineering
(217) 333-0945; pkalita@illinois.edu
Prasanta Kalita

The use of vegetative filter strips has been identified as an effective management practice to help control the movement of agricultural pollutants into water sources. These filters have the potential to reduce or stop the sediment, nutrients, pesticides, and microorganisms from entering surface or ground water.

A vegetative filter strip (VFS), also called a "buffer strip," is a designed and maintained area of vegetation located between a potential pollutant source and a receiving water body. It traps various materials when the water passes through the vegetation, either through infiltration or sedimentation. Runoff may contain sediment, organic matter, nutrients, pesticides, microorganisms, or combinations of these in suspension or in solution. The vegetation within the strip can slow the movement of water, allowing a greater contact time for infiltration, thereby decreasing the total amount of runoff. As the water infiltrates the soil, soluble nutrients move into the soil and sediment-bound particles are trapped in the dense vegetation. Nutrients that are bound to sediment particles include phosphorus and ammonia, whereas nitrate is mostly transported in solution.

An example of a functioning vegetative filter strip for a cattle farm

Figure 1. An example of a functioning vegetative filter strip for a cattle farm.

Research indicates that filter strips are an effective method of controlling and reducing agricultural pollutants from runoff. In Illinois, studies have shown that filter strips can remove 68 percent of nitrogen and phosphorus from agricultural runoff. In other parts of the country, studies have shown nutrient reductions of up to 90 percent. The removal rates depend on many factors, such as rainfall patterns, type of vegetation, soil type, and slope.

Vegetative filter strips have been used to treat a variety of wastes, including livestock waste from animal feeding operations. Animal feedlots are of great concern when it comes to water quality, due to the high levels of nutrients and pathogens contained in their runoff. Currently, the knowledge of pathogen transport from feedlots is limiting.

Cattle farm in need of vegetative filter strip system

Figure 2. Cattle farm in need of vegetative filter strip system.

The significance of VFS for removal of sediment, nutrients, and pesticides from agricultural runoff has been studied quite extensively. However, the effects of VFS and vegetation on pathogen transport are very limited. Therefore, new studies are underway to determine the parameters associated with pathogen transport in runoff from animal feeding operations and to determine the effects of VFS on pathogen transport. Some of the parameters being evaluated are the effects of land slope, soil type, vegetation, animal species, and rainfall. The objectives of these studies are to investigate microbial pathogens in runoff from animal production systems and to develop strategies to limit their transport to water sources.

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