Barriers

John Tatarko Author

04/07/2019 Added

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This video clip explains how barriers alter the effect of the wind force on the soil surface. The video discusses the different types of barriers and their advantages and disadvantages.

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[00:00:00.640]In contrast to methods which make the soil surface more resistant to the forces of wind,
[00:00:05.580]barriers alter the effect of the wind force on the soil surface.
[00:00:09.300]Barriers help by reducing wind speed on the downwind side of the barrier
[00:00:13.580]and by trapping moving soil.
[00:00:15.480]Research has shown that barriers significantly reduce wind speed
[00:00:20.920]for a distance of about 10 times the height of the barrier,
[00:00:23.980]in effect reducing the field length along the erosive wind direction.
[00:00:28.320]However, the fully protected zone of any barrier diminishes
[00:00:32.040]as wind velocity increases
[00:00:34.100]and as the wind direction deviates from perpendicular to the barrier.
[00:00:37.980]Wind breaks and shelter belts are linear plantings
[00:00:45.560]of single or multiple rows of trees or shrubs
[00:00:48.440]established for wind erosion control as well as snow management.
[00:00:52.580]They protect crops, shelter livestock, and provide wildlife habitat.
[00:00:58.080]One advantage of wind breaks over most other types of wind erosion control
[00:01:01.740]is that they are relatively permanent.
[00:01:03.640]During drought years, wind breaks may be the only effective
[00:01:08.000]and persistent control measure on cropland.
[00:01:10.300]Many of the wind breaks planted in the 1930s and 40s were wide
[00:01:16.540]because it was believed that wide belts were necessary
[00:01:19.380]to provide adequate wind reduction.
[00:01:21.160]The trend today is toward narrower plantings.
[00:01:24.460]Single row plantings are most common in field wind breaks
[00:01:27.840]because they occupy the least amount of land area
[00:01:30.840]for the amount of protection derived from them.
[00:01:33.240]The type of species planted in a wind break has a considerable
[00:01:37.580]bearing on the year-round effectiveness because the amount
[00:01:41.000]of protection depends on the barrier shape, width, height,
[00:01:44.460]and porosity.
[00:01:45.360]The seasons also govern porosity of many species and therefore
[00:01:49.860]influence the effectiveness of the wind breaks.
[00:01:52.300]During establishment of wind breaks, protection is limited
[00:01:56.420]and unless other erosion control
[00:01:57.600]measures are in place, severe damage to the plantings and the land may result.
[00:02:02.600]Cross-wind trap strips
[00:02:05.200]consist of herbaceous vegetation resistant to wind erosion established in one or more strips
[00:02:13.550]perpendicular to the prevailing wind direction. Since saltating particles can travel up to 15
[00:02:19.190]feet, the crosswind trap strips should be at least 15 feet in width and up to 25 feet for
[00:02:25.250]shorter strip vegetation. The purpose of trap strips is to trap saltating particles and to
[00:02:31.370]provide protection from the effects of wind erosion. Trap strips, however, require frequent
[00:02:36.650]and expensive maintenance. Herbaceous wind barriers are tall, non-woody vegetative barriers
[00:02:45.890]established in one to two row narrow strips across the prevailing wind direction. These are primarily
[00:02:52.050]used on soils where stubble mulching and strip cropping do not adequately control wind erosion.
[00:02:57.870]Perennial barriers are often the only control alternative here, short of retiring the land of
[00:03:04.510]permanent grass.
[00:03:05.330]Perennial grass barriers work well for wind erosion control as well as trapping snow and
[00:03:12.590]reducing evaporation on dry land cropping areas. Other advantages of these types of barriers are
[00:03:19.010]ease of establishment and low cost. Annual crops can also be used as herbaceous wind barriers,
[00:03:25.370]so one crop provides protection for another crop. Flax, grain and forage sorghum, broom corn and
[00:03:32.330]kochia are crop barriers that can provide adequate protection from wind erosion if spaced sufficiently
[00:03:38.090]close. Artificial barriers such as snow fences, board walls, bamboo and willow fences, earthen
[00:03:49.370]banks, hand inserted straw rows and rock walls have been used for wind erosion control, but only
[00:03:55.730]on a very limited basis. There is usually a very high cost in material and labor to construct these
[00:04:01.510]barriers and their use is generally restricted to high value crops. They can also be used in sand
[00:04:07.870]dune areas to aid in the initial stabilization phase while grass and trees are being established.

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Barriers

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