Buffer strip

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A buffer strip is an area of land maintained in permanent vegetation that helps to control air, soil, and water quality and other environmental problems primarily on land that is used for agriculture. Buffer strips trap sediment, and enhance filtration of nutrients and pesticides by slowing down runoff that could enter the local water supply. The root systems in these buffers hold soil particles together which stabilize nearby soil and stream banks providing protection against substantial erosion and landslides. Farmers can also use buffer strips to square up existing crop fields to provide safety in farming operations.

Buffer strips can have several different configurations of vegetation found on them varying from simply grass to combinations of grass, trees, and shrubs. Areas with diverse vegetation provide more protection from nutrient and pesticide flow and at the same time provide better biodiversity amongst plants and animals[1][2].

Many country, state, and local governments provide financial incentives for conservation programs such as buffer strips because they help meet pollution requirements. Buffer strips can also provide visual demonstration that land is under stewardship.

Contents

[edit] Types of Buffer Strips

Buffers within Fields

Grassed Waterway

A grassed waterway is a very simple way to reduce erosion and catch nutrients, pesticides and nutrients that will normally wash out of crop fields. These waterways help to carry surface water at a non-erosive velocity to an area where it will have a stable outlet (USDA, 2000). Since grassed waterways have such a concentrated flow sometimes they will not be very effective during large runoff events. Grassed waterways require very little maintenance once they are introduced. Farm machinery and cattle can cross these waterways but it is not recommended. One of the major disadvantages of waterways are actually getting them established. A late summer or early fall seeding is recommended to allow the seed to have the best chance at establishing a root system[3].

Contour Buffer Strips

This type of buffer strip is simply a strip of perennial vegetation that is alternated with wider cultivated strips of cropland. This type of buffer strip is most effective when runoff water enters uniformly as sheetflow (USDA, 2000). They are very adapted to trapping pesticides and reducing rill erosion. These buffers need to be at least 15 feet wide and make up for 20-30% of slope of an area. A lot of the time contour buffers can be used as a very inexpensive substitute for terraces. Most of the time a grass is selected that can be harvested during mid-summer. These buffers are not permanent and can be moved up and down hillsides from season to season in order to re-establish vegetation (NRCS, 2007).

Edge of Field Buffers

Vegetative Barriers

This buffer strip is much narrower than most of the other types of buffers. They are narrow, permanent strips of hardy, native, perennial grasses or shrubs planted in parallel rows to crops (Sharma, 1998). They are very affective in reducing wind and water erosion which results in sediment trapping and water infiltration. They function in similar fashion to a contour buffer strip, just much narrower (USDA, 2000).

Field Borders

This type of buffer strip is simply a band or strip of perennial vegetation that is found on the edge of a cropland field. Field borders help with runoff only when it flows over the strip. They’re very effective in benefiting spraying operations because they allow for extra room between adjacent fields. They also provide room for farming equipment to turn around. Field borders are effective in reducing wind and water erosion and provide great wildlife habitat (USDA, 2000).

Filter Strips

These strips are areas of grass or other permanent vegetation that protect riparian areas from sediment runoff, pesticides, pathogens, organics and nutrients. These strips are very important in protecting stream banks and water quality. Filter strips work best when other conservation practices are used in order to drain water in their direction (USDA, 2000). Filter strips were originally used mostly in agriculture, but now are a common practice in urban areas where water quality has become an increasingly important issue (CWP, 1997).

Riparian Forest Buffer

This type of buffer has a very diverse community of trees, shrubs and native perennial grasses. They are great for providing habitat for wildlife on land and in the water. Taller trees next to the streams help to lower water temperatures with shade which improves aquatic communities. The shrubs and grasses help to slow flooding and the larger trees can sometimes intercept nitrates before they reach the water with their deep roots (USDA, 2000).

Wind Buffers

Main article: Windbreak

The main purpose of a windbreak or a shelterbelt is to protect areas from wind. Windbreaks can also serve as an area that separates fields and protect them from spray drift. The reduction of wind erosion has many positive aspects. There are several different types of buffer strips, and you could make an argument that there are several more besides the ones that are shown above. Any type of barrier between fields or between fields and water could be considered a buffer. In this case you could also list CRP fields, wood lots, terrace back slopes, wildlife plantings and ditch banks as buffer strips too (USDA, 2000).

[edit] Wildlife Habitat

Buffer strips are very important in helping to provide habitat for all kinds of different species. They are helpful in conserving biodiversity wherever they are found for both aquatic and land species. Many buffer strips incorporate native grasses into their seeding. Native grasses are especially important to pheasants, quail, chukar and songbirds. Since buffer strip areas are often encouraged to be disturbed through management practices they provide for great habitat with a wide range of plants and insects.

Riparian buffer areas often incorporate large trees that protect stream banks and shade aquatic areas. Bare, not shaded, sediment filled channels make for very poor habitat for fish and other aquatic organisms. The shade provided by the larger trees reduces water temperatures and light intensity. The falling debris, including leaves and branches, that come from the trees often contain insects that are important to the diet of many aquatic animals. Also the large roots that extend out from the trees into the water provide for very stable habitat that shelters the aquatic community.

[edit] Pesticides and Nitrates

People have been using pesticides in order to prevent damage to their crops for centuries. The first known use of pesticides was in 500 A.D. and since the 15th century farmers have been using arsenic, mercury and lead to kill pests in their fields. In the United States pesticide use boomed in the early 1900’s and it took quite awhile before people realized some of the negative effects that pesticides can have. Many of the pesticides, like DDT, that were very harmful to the environment have been banned in most developed countries. The reasons a lot of these pesticides get banned are because of their ability to pass through the soil with out being caught and taken up by plants before they reach groundwater (Chem-online.org). There are two key words to remember when it comes to pesticides and buffer strips; adsorption and absorption. When a pesticide is held on to the surface of a material, often connected to a soil particle, this is considered adsorption. When a pesticide is actually taken up inside of a material, like a plant, it is considered absorption. All of the pesticides very in how tightly they are adsorbed by soil particles. Also the type of soil can make a difference in how well they adsorb the pesticides (USDA, 2000).

Another foreign material that can damage water and soil quality is nitrates. Water with a high amount of nitrates can be very harmful to humans and livestock alike. When nitrates are consumed in water they are converted to nitrites. Nitrites take away oxygen in the blood and are responsible for many stillbirths and abortions[4]. In contrast to pesticides, most nitrates are water soluble and aren’t readily adsorbed by soil particles. Nitrate runoff most often occurs when nitrogen fertilizer or manure is spread on a field and is quickly washed off by heavy rains or floods. In order to correctly stop nitrate flow roots of conservation buffers plants need to intercept this subsurface flow.

[edit] References

  1. ^ USDA & NRCS, (2000). Conservation Buffers to Reduce Pesticide Losses. Retrieved December 11, 2007
  2. ^ (2000). Buffer Strips- Common Sense Conservation. Retrieved December 11, 2007, from Woodstock Conservation Commission
  3. ^ Stone, R. (1997). Retrieved December 11, 2007, from Ontario Ministry of Agriculture, Food and Rural Affairs
  4. ^ (2007). The Nitrate Elimination Co., Inc. Retrieved December 11, 2007, from NECI