Contour Buffer Strips

What are contour buffer strips?

Contour buffer strips are narrow strips of perennial vegetation alternated with wider cultivated strips, farmed on the contour.

The strips of permanent vegetation slow runoff and trap sediment and other water borne contaminants. Combined with the benefits of farming on the contour, contour buffer strips are an effective conservation practice.

This practice is most effective when used with other conservation practices such as residue and tillage management and crop rotation.

How it helps the land

Buffer strips established on the contour can reduce sheet and rill erosion by as much as 30 percent. Buffer strips can also provide food and nesting cover for wildlife.

Where the practice applies

Contour buffer strips can be used on any cropland where sheet and rill erosion are a problem.

It is most suitable on uniform slopes. The narrow strips of permanent vegetative cover are not a part of the normal crop rotation. This practice does not apply to situations where the width of the buffer strip will be equal to or exceed the width of adjoining crop strips.

Where to get help

For assistance in planning and establishing contour buffer strips on your farm contact your Natural Resources Conservation Service (NRCS) office. For more job sheets and conservation information visit the NRCS website at www.ia.nrcs.usda.gov.

Applying the practice

This practice is considered applied when the contour buffer strips are installed according to the specifications above. Select one of two methods to lay out a contour buffer strip system. One layout method results in parallel buffer strip widths, the other results in parallel cultivated crop strip widths.

• Parallel cultivated strips
  • Generally, more area of the field will be in the buffer strip.
  •  Farmed area will have parallel rows.
  • The width of the buffer strip varies; make sure the width stays  15 feet or greater.
• Parallel grassed strips
  • More of the area will be farmed.
  • Cropped strip width varies. There will be more short rows.
  • Buffer strips can be used as turn areas to plant point rows.

How to lay out parallel cultivated strips

1. Establish a contour line on the slope, approximately eye level height down from the high point on the ridge. This becomes the top edge of the buffer strip. (For instructions on laying out contour lines refer to the NRCS job sheet on contouring).
2. On the steepest part of the slope, measure down the hill from the contour line, the width of the buffer strip. From that point establish a contour line that becomes the downhill edge of the buffer strip.
3. From the lower contour line, measure downhill to flag a parallel line the width of the cultivated strip. From this flag line, return to step 2 above. Continue steps 2 & 3 as needed.

How to lay out parallel grassed strips

1. Establish a contour line on the slope, approximately eye level height down from the high point on the ridge. This becomes the top edge of the buffer strip.
2. Measure down from the contour line a parallel strip the width of the buffer strip. This will establish the lower edge of the buffer strip.
3. On the steepest part of the slope, measure down the hill from the lower edge of the buffer strip, the width of the cultivated strip. Use the elevation at that point to establish a contour line that becomes the downhill edge of the next cultivated strip. Continue steps 2 & 3 as needed.

With both systems of layout

Adjust the lines to stay on the contour. Make grass turn strips on narrow ridges, where sharp curves occur. Establish waterways in drainageways. Consider conditions unique to the field like sidehill seeps, entry areas to the field, and short steep areas during planning.

Establishing the vegetation

• Prepare a firm seedbed.
• Apply lime and fertilizer before seeding according to soil tests.
• Seed the area with the recommended seeding mixture. Oats may be seeded as a companion crop at 1 to 1.5 bushels per acre during the spring. Mow oats before they head out or harvest them for grain if it is allowed.
• Drill grass and legume seed uniformly over the strip 1/4" to 1/2" deep or broadcast uniformly over the strip. Harrow and cultipack to establish good seed to soil contact.

Seed during the spring seeding period, March 1 to May 15, or during the late summer seeding period, August 1 to September 15. For warm season grasses seed April 15 to July 1. Refer to your conservation plan for your planned planting date.

Maintaining the practice

Contour buffer strips will need maintenance to control weeds and brush. Buffer strips may be harvested for hay. However to be most effective, buffer strips should have tall vegetation in spring and early summer. To help ground nesting birds and their young, delay mowing until after August 1.

Contour buffer strips may be rotated, but the proportion of the slope in buffer strips must remain the same each year. The maximum cultivated strip must not exceed the width stated in the "Requirements" section.

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