Windbreaks for Arkansas Poultry Farms - By G.T. Tabler, Poultry Science Department at the University of Arkansas's Avian Advice - Windbreaks are barriers that have been used for centuries to reduce and redirect wind. They were first used in the mid-1400’s when the Scottish Parliament urged the planting of tree belts to protect agricultural production (Droze, 1977).

Introduction

Windbreaks are common in regions like the Western, North Central, and Great Plains of the United States where there is minimal forest cover, strong winds, large amounts of snow, and extreme temperature fluctuations. However, since windbreaks have also been used for privacy screens, dust control, odor control and noise reduction, the Arkansas poultry industry should give them serious consideration. The ever-increasing non-farm population influx into rural, poultry producing areas of the state is adding to the number of complaints and lawsuits between non-farm and farm segments of the population.

Windbreaks have the potential to address some of these problems and could improve property values. In addition, planting trees and shrubs is seen as environmentally friendly; therefore, windbreaks around poultry houses could further demonstrate a producer’s commitment to a safe, healthy environment now and in the future.

Windbreak Benefits

Well-designed windbreaks can cut energy costs of a typical farm or ranch home as much as 20 to 40 percent (Wight et al., 1991). Individual savings depend on the local site, climate conditions, and building construction quality, as well as the design and construction of the windbreak. Since windbreaks reduce the force of the wind blowing against the buildings and, in turn, the amount of cold air entering the building, unprotected poultry houses, with poorly fitting doors, numerous cracks or gaps and poor-quality curtains could probably benefit greatly from a well-designed windbreak. A moderately dense windbreak will reduce a 20 mph wind to approximately 5 mph out to a distance of five times the effective height of the windbreak. Table 1 lists wind reductions at various distances upwind and downwind of windbreaks.

Many poultry producers also raise beef cattle. When windbreaks are used to protect cattle fed in open pastures or lots mortality is reduced, feed efficiency is improved and weight losses are reduced by as much as 50 percent. Studies in Iowa over a five year period showed that sheltered cattle gained an average of 80 pounds more per year and on average consumed 129 pounds less feed per hundredweight of gain than those not sheltered (Slusher and Wallace, 1997).

Farmstead windbreaks can also screen undesirable sights, sounds, smells and dust and thus improve living conditions for neighbors, particularly on the downwind side. The plants within the windbreak will absorb some odors while others may be masked by the more desirable smells of aromatic leaves or flowering shrubs that may make up the windbreak. Windbreaks can also reduce noise by deflecting sound off branches and tree trunks or by absorbing sound with leaves, needles, twigs, and smaller branches. For poultry producers this could mean a reduction in noise from tunnel ventilation fans that may, during summer, run 24 hours a day for weeks. In addition, to some degree, undesirable noises may be masked by the more desirable sounds of singing birds attracted by the windbreak and the rustling of leaves. For maximum effectiveness, tree and shrub belts should be tall, dense and located closer to the noise source than to the area protected (Slusher and Wallace, 1997). Poultry farms are a common sight along many roadways in western Arkansas. Screening these with windbreaks would remove them from the public’s eye while also beautifying your farming operation and displaying your concern for the environment.

In temperate regions windbreaks can be a major component of successful agricultural systems. However, to be successful, windbreak integration requires a thorough understanding of the agricultural system involved, a basic understanding of how windbreaks work and a working knowledge local conditions.

Height, Length and Structure of Windbreaks

Windbreak height is the most important factor determining the distance downwind protected by a windbreak. For maximum efficiency, the uninterrupted length of the windbreak should be at least 10 times its height (Brandle et al., 2002). Windbreaks usually require at least two kinds of trees with different growth characteristics to provide foliage density at various heights over a period of years (Slusher and Wallace, 1997). Table 2 lists trees and shrubs that have been used in Missouri windbreaks; many of these same species would work well in Arkansas windbreaks as well. Conifer species, such as cedar and pine, and shrubs with multiple stems tend to provide better year-round density, while taller hardwood species, such as ash, oak, or hackberry, generally are used to provide greater height.

The amount of wind speed reduction that occurs is determined by the structure of the trees involved. As wind flows through a windbreak, the trunk, branches and leaves absorb some of the momentum of the wind and the roughness of the tree surfaces further slows wind speed. However, density should be adjusted to meet particular objectives. In general, windbreaks with higher densities (multiple rows) are used to protect wildlife, farmsteads, or homesites, while windbreaks with lower densities are used to protect crop fields. Windbreak density is the ratio of the solid portion of the windbreak to the total area of the windbreak. A windbreak density of 40 to 60 percent provides maximum downwind protection in addition to providing tremendous soil erosion control (Brandle et al., 2002).

The prevailing winds in winter are from the north and northwest in Arkansas, so protective windbreaks should be located along the north and west sides of your farmstead. However, windbreaks used for visual screening and dust, odor and noise control near tunnel fans can be placed where needed with proper planning. Windbreaks with both deciduous and evergreen species must have adequate space. If evergreen and deciduous trees are planted as close as 6 to 8 feet apart, the deciduous trees will soon overshadow the evergreens. When this happens, the growth of the evergreens will be stunted, their form will be ruined and their effectiveness greatly reduced. There must be at least 15 to 20 feet of space between rows of evergreen and deciduous species (Slusher and Wallace, 1997).

Considerations and Tree Spacing

Slusher and Wallace (1997) suggest keeping the following considerations in mind as you plan your windbreak;

• Locate the windbreak where it will be most effective.
• Design the windbreak to fit the available space and to meet the purpose of the planting. Design must allow for proper spacing (see below) for tree growth and for use of maintenance equipment.
• Select tree and shrub species that are well adapted to your soil and climate conditions. Order trees early.
• Properly prepare the planting sight and fence areas accessible to livestock.
• Arrange for necessary planting labor and equipment.
• Provide care and protection for young seedlings.
• Provide proper management practices after windbreak establishment.

When planning the spacing of trees the probable size of the crowns after the trees reach 20 to 30 years of age should be considered. Although a wider spacing means that it will take longer for trees to form an effective wind barrier, the delay in windbreak effectiveness will be more than offset by the increased tree growth rate. In addition, trees that have adequate growing space will live longer, retain their lower limbs better and produce more foliage. Furthermore, the reduced windbreak effectiveness produced by wider spacing can be overcome by staggering the trees in adjacent rows. Rows should be spaced from 15 to 30 feet from each other, depending on the types of trees or shrubs in the adjacent row. Slusher and Wallace (1997) recommend the following spacing for various trees and shrubs:

• Space 10 to 12 feet between shrub rows.
• Space 15 to 20 feet between shrub and tree rows.
• Space 15 to 20 feet between medium and tall tree rows.
• Space 20 feet between tall evergreen rows.
• Space a minimum of 20 feet between tall evergreen and tall deciduous tree rows.

Remember that spacing must allow for proper use of suitable maintenance equipment. Between trees in a row:

• Allow 4 to 6 feet for deciduous shrubs.
• Allow 10 to 16 feet between medium-sized evergreens.
• Allow 12 to 20 feet between deciduous trees.
• Allow 10 to 16 feet between tall evergreen trees.

Summary

Winds of change are sweeping across the American agricultural landscape. The general public is no longer as tolerant of agricultural practices as they once were. In addition, agricultural producers are a small minority of the population and must therefore utilize strategies that allow production to increase, while at the same time, living in harmony with their neighbors and, in turn, minimizing complaints or lawsuits from the non-farm population. One such strategy for Arkansas poultry producers is the use of windbreaks.

Windbreaks are an old technology used to reduce wind speed but they also have the potential to visually screen poultry houses from public view, disperse odors, dust and noise before these pollutants have a chance to affect the neighbors. Also, in today’s environmentally conscious society, planting trees is “good” thing to do and may reflect positively on agricultural producers who otherwise might be viewed unfavorably by much of the non-farm population. Be aware that constructing a successful windbreak is no small undertaking so do your homework before grabbing your shovel. Contact your local Extension office, Arkansas Forestry Commission, NRCS office, or local landscape nursery for assistance with planning and constructing a windbreak that will meet the needs of your particular farming operation.

References

Brandle, J. R., X. Zhou, and L. Hodges. 2002. How windbreaks work. University of Nebraska Extension EC 02-1763-X. University of Nebraska, Lincoln.
Brandle, J. R., L. Hodges, and X. H. Zhou. 2004. Windbreaks in North American agricultural systems. Agroforestry Systems 61:65-78.
Droze, W. H. 1977. Trees, Prairies, and People: A History of Tree Planting in the Plains States. USDA Forest Service and Texas Women’s University Press, Denton, TX. 313 pp.
Slusher, J. P., and D. Wallace. 1997. Planning tree windbreaks in Missouri. MU Guide G5900. University Extension. University of Missouri-Columbia.
Wight, B., T. K. Boes, and J. R. Brandle. 1991. Windbreaks for rural living. University of Nebraska Extension EC 91-1767-X. University of Nebraska, Lincoln.

Source: Avian Advice - Winter 2005 - Volume 7, Number 1