Chapter 6: Windbreaks

Training Manual for Applied Agroforestry Practices – 2021

Edition

This guide is intended to help you design and

manage the interactive agroforestry practice of

windbreaks. Properly applied on a landscape, a

windbreak can enhance and diversify farm

income opportunities, improve the environment

and create wildlife habitat. By developing an

understanding of the interactions between the

windbreak (trees, shrubs and grasses) and the

adjacent land area, its layout can be most effective

at meeting the goals for which it is, or has been,

established. By understanding the needs of each

of the windbreak’s component parts, the

windbreak can be managed to best maintain its

effectiveness over time, and also sustain its

contributions to the farm or ranch.

Windbreaks Defined

A windbreak is any barrier (natural or artificial)

that reduces troublesome winds by creating a

wind shadow to the leeward (down-wind) side. Its

major function is to reduce the velocity of the

wind. A windbreak must be 2.5 feet or higher

to have a significant effect. Many kinds of

materials can be used for a windbreak,

including trees, shrubs, tall perennial or

annual plants (e.g., switchgrass or

sunflowers) that will attain a sufficient

height to create the desired wind shadow.

Agricultural practices benefitting from

properly applied windbreaks include:

•

Crop production

•

Soil conservation

•

Livestock and dairy cattle husbandry

•

Livestock confinement facilities.

•

Nut, fruit, and berry crops

Crops that can be produced from actively

managed windbreaks include:

•

Nuts, fruits, berries

•

Timber, fencepost, firewood

•

Christmas trees

•

Boughs, cones, wreaths

•

Landscape plants

•

Shade-tolerant plants such as those

grown in the forest farming practice

•

Lease hunting opportunities when

managed for wildlife benefits

In this chapter:

•

Defining a Windbreak

•

How Windbreaks Function

•

Windbreak Benefits to Soil, Crops

and Livestock

•

Windbreak Design

•

Productive Windbreaks

•

Site Preparation, Planting and

Maintenance

Appendix:

•

Non-Agroforestry Uses of

Windbreaks:

Windbreaks for Homes

Windbreaks for Livestock Odor

Reduction

Living Snow Fences

Windbreaks for Wildlife

•

Success Stories

•

Economic Incentives

•

Additional Resources

University of Missouri Center for Agroforestry

The windbreak or shelterbelt practice,

uses intensive management for growing

trees, shrubs and/or grasses adjacent to other

agricultural practices, and consists of one or

more rows of closely spaced trees and/or

shrubs planted at right angles to the

prevailing winds. A windbreak becomes

important to the agricultural system by

enhancing production, or conservation, as it

modifies air movement and wind speeds

resulting in microclimatic changes. The terms

windbreak and shelterbelt can be used

interchangeably.

How Windbreaks Function

Windbreak Height. Height (referred to as ‘H’)

is the most important factor determining the

downwind area of protection. The windbreak ‘H’

is the height of the tallest row of trees in the

windbreak. The windbreak will reduce wind

speed for 2 to 5 times the height of the wind-

break (2H to 5H) on the upwind side and up to

30H on the downwind side of the barrier. The

area protected is a direct result of the height

and density.

Windbreak Density. Density is the ratio of the

solid portion of the barrier to the total area of

the barrier. Wind flows through the open

portions of a windbreak, thus the more solid the

windbreak, the less wind passes through. By

adjusting windbreak density, different wind

flow patterns and areas of protection are

established.

Density level is manipulated by choice of plant

materials (e.g., deciduous vs. conifer); and plant

arrangement. By combining low growing

shrubs with medium and tall deciduous trees,

dense plant material is provided at three levels

(low, middle and upper) of the windbreak

during the growing season. However, during the

winter, the density would decrease due to the

loss of foliage. Consequently, a conifer

component would be desirable for year-round

protection.

• Dense (60-80%) = Maximum wind

reduction but short wind shadow

• Moderately Dense (40-60%) = Less wind

reduction but longer wind shadow

• Under 40% = Effective for snow distribution

across a field

The term windbreak porosity may also be used

to characterize this structural element. The

percentage of porosity is the amount of open

spaces in the windbreak when viewed perpendicular

Seven Windbreak Structural Elements

Determine Effectiveness

•

Height

•

Density

•

Orientation

•

Length

•

Width

•

Continuity/uniformity

•

Cross-sectional shape

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to the windbreak. In other words,

porosity is the inverse of density, i.e., a 60

percent dense windbreak would be 40 percent

porous.

Fig. 1.

Wind speed reduction to the lee of windbreaks with

different densities.

The degree of density will impact the extent of

the area being protected and the magnitude of

protection as shown in Figure 1. A solid fence

(100% density) provides maximum wind

reduction, but the area of wind reduction is

shorter than with a dense tree windbreak. The

dense windbreak (60-80%) provides a greater

area of protection, and the magnitude of wind

reduction is as good as the solid structural

fence or wall. For the moderately dense wind-

break (40-60%), the magnitude of wind reduc-

tion is somewhat less but the wind shadow is at

its maximum. Once the density drops below

40%, the effectiveness of the windbreak begins

to decline. However, the 25-35% density level

is very effective for even distribution of snow

across a field for moisture management. This

density level is not as good for stopping wind

erosion.

Windbreak Orientation. Windbreaks are

most effective when oriented at right angles to

prevailing or troublesome winds, (Fig. 2, be-

low). The best orientation for each windbreak

depends on the objectives for the windbreak. A

key point to remember is that although the

troublesome wind may occur primarily from

one direction, it rarely blows exclusively from

that direction. As the wind changes direction

and is no longer blowing directly against the

windbreak, the protected area decreases.

Fig. 2.

Windbreak Design Options.

Windbreak Length. Although the height of

the windbreak determines the extent of the

protected area downwind, the length of a

windbreak determines the amount of total area

receiving protection. For maximum efficiency,

the uninterrupted length of a windbreak should

exceed the height by at least 10:1 (i.e., a

windbreak 30 feet tall needs to be at least 300

feet long). The ratio reduces the influence of

end-turbulence on the total protected area.

Windbreak Width. The width primarily serves

as a means to manipulate the desired density of

the windbreak. The number of rows,

the distance between trees, and species

composition are factors controlling windbreak

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density. Increasing the number of rows or

decreasing the distance between trees

increases density and provides a more solid

barrier to the wind. A wider windbreak can

also increase the value of the windbreak

for wildlife and offers opportunities to

produce products.

Windbreak Continuity. Continuity influences

efficiency. Gaps in a windbreak become funnels

that concentrate wind flow, creating areas on the

downwind side of the gap in which wind speeds

often exceed open field wind velocities. Gaps will

decrease the windbreak’s effective- ness. Access

lanes through a windbreak should be avoided or

minimized.

Windbreak Cross-Sectional Shape. Some

windbreak guides call for a “hip-roof shape” to

assist in “lifting” the wind. However, the cross-

sectional shape of windbreaks with equal

densities has minimal influence on wind

velocities within 10H of the leeward side of a

barrier. Be- yond 10H, straight sides provide

slightly more protection than slanted sides

because more wind passes through the trees

and extends the protected area farther to the

leeward.

Windbreak Benefits

Windbreaks offer a variety of potential

environmental and financial benefits to a farm

or ranch enterprise through protection of crops

and livestock. The rural community also

benefits from improved air quality through

wind speed reductions and the physical capture

of airborne particulates including dust, smoke,

pesticide droplets and odors. Windbreaks also

provide aesthetic diversity by adding trees in an

agricultural landscape and enhance wildlife

habitats and corridors through the addition of

tree, shrub and herbaceous cover.

Benefits for the Soil

Windbreaks have been widely recognized as a

key tool to reduce wind erosion. When wind

speed is reduced, the wind erosion process

cannot start. Wind erosion can rob land of

precious topsoil containing nutrients and

organic matter. This loss can lead to reduced

productivity and the need to add more

nutrients. Wind erosion potential is the greatest

when fields are very wide and the soil is bare

and smooth. Windbreaks combined with other

wind erosion control measures (e.g., reduced

tillage, herbaceous wind barriers) create a

conservation approach to tolerating wide

weather extremes.

Disadvantages of Windbreaks

•

Require more intensive management

•

Need specialized equipment for tree/

shrub management

•

Remove land from annual crop

production

•

Financial returns increase gradually as a

windbreak grows

•

May harbor harmful crop pests, e.g.,

insects & weeds

Advantages of Windbreaks

•

Enhance crop yield

•

Protect soil from wind erosion

•

Shelter livestock and crops

•

Capture water runoff and nutrients

•

Improve irrigation efficiency

•

Filter and reduce dust

•

Help control odors

•

Screen unsightly areas

•

Provide wildlife travel corridors and

habitat

•

Protect structures (homes, outbuildings,

roads)

•

Reduce noise

•

Improve aesthetics

Training Manual for Applied Agroforestry Practices – 2021

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Fig. 3.

Windbreak Benefits for

Crops.

Crop Windbreaks: Weighted Average Crop Yield

Increase

Corn

12%

Soybeans

13%

Barley

25%

Winter Wheat

23%

Hay

20%

Spring Wheat

Benefits for Crops

Windbreaks improve crop production and

quality by modifying the microclimate and

reducing wind erosion. They protect crops from

insect pests by reduced crop visibility, dilution

of pest hosts due to plant diversity, interference

with pest movement, creation of environments

less favorable to pests and more favorable to

beneficial insects. They can be designed to

manage snow drifting to maximize use of the

moisture for crops. Windbreaks improve

irrigation efficiency by reducing evaporation

losses; and improve water quality through

interception of sediment and interception,

sequestration and decomposition of agricultural

chemicals in the tree, shrub and herbaceous

rhizosphere.

When field windbreaks are suggested to

landowners, they often have a mental image of

crop reduction and/or loss adjacent to the

windbreak and from the space occupied by

the windbreak. What is often not recognized is

the potential for increased crop quality and

quantity on the leeward (downwind) side of

the windbreak. Many years of field research

have shown there is a yield advantage for many

ops when protected

by a windbreak. This

yield increase generally

occurs from 1.5/2H to

10-12H on the leeward

side of the windbreak

(Fig. 3). The amount of

yield increase will vary

from year to year due to

different weather

conditions. There will also be some variation

due to soils and the types of trees used in the

windbreak (i.e., less competitive trees result in

greater gains). The yield advantage is normally

more than enough to offset the decrease in yield

immediately adjacent to the windbreak and the

land occupied by the windbreak. Some

landowners will plant a deep rooted crop such

as alfalfa adjacent to the windbreak in the area

most impacted by competition and are able to

gain good quality forage.

This field windbreak is designed to provide year-round

protection by incorporating cedar and pine outer rows with

an interior row of deciduous shrubs.

Benefits to Orchards and

Vegetable Crops

In addition to the traditional commodity crops,

windbreaks are also used to protect a variety

University of Missouri Center for Agroforestry

of horticultural crops including many fruit and

vegetable crops. Some of the key benefits of

protecting these types of crops include:

improved crop quality from reduced bruising,

better pollination from insects due to less

wind, and early maturing of the crops resulting

in possible marketing advantages.

Windbreaks around orchards are also being

examined for their use in preventing off-site

drifting of pesticides. Many orchards and

other farms are being engulfed by housing

developments. Windbreaks can help buffer

potential land-use conflicts.

Benefits to Livestock

Windbreaks provide valuable protection to

livestock especially for young animals and in

areas with cold northerly winds during winter

and early spring. Reducing the wind impacts

lowers animal stress and improves general

health resulting better livestock production by

increasing feed efficiency and weight gains,

improving survival of newborns and

increasing milk production. Windbreaks can

also provide living screens to separate

incompatible uses (i.e., livestock facilities from

suburban residences).

Windbreak Design

Designing windbreaks requires the planner to

be able to manipulate the different structural

components of a windbreak in order to achieve

the desired effect. Climatic and physical effects

such as wind speed, apparent air temperature,

snow deposition and evapotranspiration are

modified as a result of the structural

characteristics of the windbreak.

Ask Yourself: What needs to be protected?

•

Crops/orchards

•

Soil

•

Livestock and/or Livestock Buildings

1) Determining the Windbreak Purpose

As noted previously, a windbreak can have

a variety of purposes ranging from crop

protection to snow management. The design

of the windbreak is dependent upon the

purpose(s) desired. To determine the purpose(s)

requires understanding the desired objectives of

the landowner and the physical site

characteristics.

The first step in design is to interview the

farmer/landowner to ascertain their

objectives or purposes for the windbreak.

A questioning strategy can be effective such as:

Crops

• H

ave you had any wind erosion from your

fields? If so,

o When did it occur?

o From which direction(s) does the wind

cause the most problem(s)?

o Are you using other wind erosion

control practices, e.g., reduced tillage?

• Have you had any crop damage or loss from

the wind or blowing soil?

o When did it occur?

o From which direction(s) does the wind

cause the most problem(s)?

o What crops are you growing that may

be wind sensitive?

• Are you growing crops that need pollination?

Livestock

• When do your livestock need the most wind

protection?

• What livestock pastures, lots or structures

need wind protection?

• Do we need to be concerned with summer air

movement in the livestock area?

• Which access roads need to be kept clear of

snow?

• Is there a drainage issue associated with

rain or snowmelt runoff?

2) Site Evaluation

The next step is to evaluate the site conditions that

may affect windbreak design and application. Use

a conservation plan map or photo to identify fields

in need of protection, existing windbreaks, soil

problems, utilities, direction of prevailing erosive

winds, property lines, roads and access lanes. (Fig.

4, next page.)

Training Manual for Applied Agroforestry Practices – 2021

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Fig. 4. Area sketch for site evaluation.

• Identify all areas needing protection based

on the troublesome wind direction(s).

• Inventory the soils. Begin a starter list of

species adapted to the soils.

• Observe the topography to determine any

drainage concerns either into or away from

the windbreak (especially snowmelt and

feedlot runoff)

• Locate property lines, overhead and under-

ground utilities (electric, telephone, gas,

and/ or sewer), and existing trees or shrubs

which may be within or adjacent to the

proposed windbreak.

• Identify any access roads or lanes that

could cause breaks in the windbreak.

• Locate the windbreak to avoid obstructing

the winter sun, or oncoming traffic near

driveways.

• Identify protection needs for the wind-

break, such as fencing to keep out live-

stock.

• Observe any existing plant species which

may be alternate hosts for pathogens, e.g.,

cedar-apple rust.

• Inventory existing wildlife habitat and

wildlife species in the area so the wind-

break may complement.

3) De

sign Considerations for Different

Windbreaks

Windbreak Design Tips for Crop Fields

• For crop protection/production and/or

uniform snow distribution, windbreak-

to-windbreak intervals should be 15

to 20H. For crops highly susceptible to

damage from wind or small amounts of

wind-blown soil during some portion of

the growing season, a spacing interval of

6-10H provides a high degree of

protection.

• For erosion control purposes, the Natural

Resources Conservation Service uses a

rule-of thumb of “no erosion out to 10H

leeward” -- leading to a windbreak-to-

windbreak interval of 10H plus the

distance protected by the agronomic

system (i.e., standing crop, crop residues,

cropping pattern, ridging) being used.

• Different design densities and heights

result in different snow drift patterns. For

example, if the landowner wants to spread

snow evenly across a field to improve soil

moisture in a crop field, the windbreak

design density should range from 25 to 35

percent. This would be roughly equivalent

to a single row of deciduous trees without

leaves at a wide spacing (15 to 20 feet). If

soil erosion is a potential problem during

the time the windbreak is at this density

level, additional conservation measures

will be needed.

University of Missouri Center for Agroforestry

Windbreak Design Tips for Livestock

• Greatest wind protection occurs from 2H to

5H leeward of the tallest tree row.

• For wind and snow protection, the most

windward row needs to be 100 to 200 feet

from the windward edge of the primary

protection area.

• Allow room for snow deposition outside of

feeding area. Care must also be taken to

accommodate the drainage both from the

clean water runoff from the windbreak (i.e.

snowmelt) and drainage from the livestock

feeding area. Effluent from the feeding area

can harm and sometimes kill trees and

shrubs.

• Critical temperatures for beef cattle are

determined in part by the condition of

the coat. Below the critical temperature,

livestock must expend more energy to keep

warm.

Livestock Critical Temperatures

Coat Description Critical Temperature

Summer coat or wet 59

Fall coat 45

Winter coat 32

Heavy winter coat 18

Adapted from D.R. Ames, Kansas State University

General Design Considerations

• Avoid creating gaps with access roads cut

through a windbreak. Wind flow increases

through gaps decreasing windbreak

effectiveness. Where needed, design the

opening at an angle to prevailing winds.

Lanes or roads through single-row barriers

should be avoided; where necessary, locate

them 100 to 500 feet from the ends of the

windbreak.

• Locate new rows of trees 50 feet from

existing trees.

• Stay away from subsurface drain fields and

overhead utilities.

• Avoid locating windbreaks within 200 feet

of road intersections to prevent poor driver

visibility.

Selecting Tree and Shrub Species

All species of trees and shrubs do not grow at

the same rate nor do they grow to the same

mature height. Likewise, adapted species vary

in their growth on different soils within a

geographical area. The amount of available

soil moisture during the growing season and

soil aeration are two important factors

affecting tree and shrub growth. These factors

are largely determined by soil texture, soil

depth and climate.

nservation tree and shrub suitability groups

have been developed as a guide for selecting

species best suited to different kinds of soils, and

climate, predicting height growth at 20

•

Plan for 40-60 % density for crop and

soil protection.

•

Plan for 25 - 35% density for snow

distribution.

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years, and measuring effectiveness. These

guides should be available in the NRCS Field

Office Technical Guide. Information

about different plants can also be

obtained from the USDA plants data-

base at www.plants.usda.gov.

In addition to selecting plants adapted to the

climate and soil, plants need to be selected that

have the greatest potential for meeting land-

owner objectives. The primary objective is to

select plants that will provide the desired level

of wind protection in a reasonable length of time

(within 10 years). This means selecting species

that will give the appropriate level of density

and optimum height for the site. For example,

conifers need to be considered if optimum year-

round wind protection is desired. If wildlife is

desired, select appropriate plants for the

desired animals or birds.

Productive Windbreaks

For most of the other agroforestry practices, e.g.,

Alley Cropping and Silvopasture, a market- able

product is typically produced from the woody

component. Windbreaks have historically been

a conservation practice providing benefits to the

adjacent area by reducing wind impacts. The

trees and shrubs in a windbreak have rarely

been managed to sell a product. In older

windbreaks planted in the 1930’s and 1940’s,

plants were chosen that could provide fruit for

home consumption and trees were cut for use as

fence posts and rough lumber on the farm. The

concept of producing usable products from

windbreaks and other conservation practices

has recently been revived and promoted in

Productive Conservation: Growing Specialty

Forest Products in Agroforestry Plantings.

For

example, nut and fruit producing plants

could be incorporated into a windbreak design

with the intent of harvesting the fruits/nuts as

a product. The harvesting would not impact the

other benefits of the windbreak. Some

commonly harvested fruits include

chokecherry, highbush cranberry, sand cherry,

currants, Corneliacherry dogwood, jostaberry,

Nanking cherry, chokeberry, buffaloberry,

pawpaw, persimmon, and many others. All are

harvested for home consumption, but many are

also gathered for commercial use as fresh fruit,

jams, jellies, syrups, juices, concentrates,

confections and wines.

A second possible enterprise could be

decorative woody florals. Any woody plant

species that has a colorful or unusually shaped

stem, bud, flower, fruit or even leaf can become

a decorative floral product. Some plant

examples include stems from red and yellow-

stemmed dogwoods; and curly, pussy, flame and

basket willows. Even though the stems of these

plants will be harvested, most of them will re-

sprout from the roots restoring their value as

part of the windbreak.

With any of these concepts, careful advanced

planning is needed. Some unique challenges

include understanding available markets,

timing of harvest, perishability of the product,

available labor, wildlife pressure, year-to-year

production, etc. Once these issues have been

resolved, thought is needed to decide how to

incorporate the plants into the windbreak

design. If the plants that will be harvested are

primarily shrubs, the design can be fairly easy

since shrubs typically are included in the outer

or inner rows which will make access easier.

Growing specialty forest products in wind-

breaks can provide supplemental income while

at the same time improve the environment.

Another advantage is that the windbreak will

receive more management care and could

result in a longer lasting planting. Success will

only occur if the grower is a skilled manager

and an effective marketer.

Windbreak Plant Materials

Select plants adapted to:

Climate

Soils

Select to meet objectives:

Foliage density characteristics

Height potential

- Wildlife needs

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Windbreak Site Preparation,

Planting and Maintenance

Site Preparation

Site preparation is an important first step to

ensure successful survival of the trees and

shrubs in the windbreak. The goal is to

maximize the amount of moisture at the site

and to minimize the potential for weed

competition. The type of site preparation used

depends on the soil and existing vegetation at

the site. With sandy soils, care must be given to

avoid wind erosion problems. On sloping sites,

precautions must be taken to prevent water

erosion. Site preparation can be accomplished

either mechanically (e.g., tillage equipment

including chisel plow, disc, rototiller, or

scalper), chemically (pre and/or postemergent

herbicides) or a combination of both.

In arid areas where trees are difficult to grow

shrubs or tall native grasses may be used to

provide crop protection, to control wind erosion,

and to capture snow for crop production.

Maintenance

The goal is to maintain the health and vigor of

individual trees and shrubs while maintaining

the overall structure of the windbreak as an

effective wind barrier. With proper care, a

windbreak will serve a long life of protection.

Planting

Tree planting methods include using either a

tree planting machine or hand planting tools.

For both methods, some key techniques need

to be followed:

• Do not plant on hot, windy days.

• Prevent roots from drying out.

• Do not plant when the temperature is

freezing or below.

• Plant seedlings in a vertical position with

root collar 1” below soil surface.

• Prepare a trench or hole deep and wide

enough to permit roots to spread out

naturally; avoid “J rooting” - prune roots as

needed to prevent J roots.

• Pack soil firmly around roots to eliminate

air pockets.

• W

eed/grass control: Weeds need to be

minimized usually for the first three to five

years in a band about three to four feet on

each side of the rows of trees or shrubs.

The area between the rows can be planted

to an annual cover crop (e.g., grain/forage

sorghum, oats, corn, millet, wheat, rye, or

sunflowers) which can help control weeds,

provide wildlife cover, and protect young

tree seedlings from soil or wind abrasion.

• Supplemental irrigation: Irrigation (e.g.,

hand, drip, sprinkler, furrow or flood) is

not a substitute for good site preparation

and weed/grass control. Irrigation should

be used when soil moisture conditions are

extremely dry at planting time or during a

prolonged drought after planting.

• Replanting: Replant all trees and shrubs

that have failed in order to fill in the gaps

in the windbreak. Replant annually for at

least three years after the initial planting

and continue until a full stand of trees is

attained.

Site preparation

•

Maximize moisture

•

Minimize competition

•

Match the site

•

Be timely

•

Care for plants

•

Plant at correct depth

Windbreak maintenance

•

Weed/grass control for the first 3 to 5

years with optional cover crop between

rows

•

Use supplemental water to ensure early

survival and development

•

Replant to fill gaps

•

Protect from animals and pests

•

Use corrective thinning and pruning

•

Do not fertilize (cost prohibitive)

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• Animal Protection: Establish appropriate

fencing to prevent livestock and large mam-

mal damage. Controlling small mammals

can include repellents, traps, special

fencing, and seedling protectors (e.g.

photodegradable plastic tubing or mesh

netting). Consult with local and state

game/wildlife specialists for control

measures for your area.

• Pest control: Periodic inspection of the

crops and trees is recommended to

detect and identify possible pests. These

inspections and in some cases the use of

pheromone traps will help determine when

corrective action is warranted.

• Pruning: Hail, wind or snow storms often

cause breakage of limbs and sometimes

the main trunk(s) of the trees and shrubs.

Remove broken limbs and tops.

• Fertilization: Generally, fertilization of

windbreaks is not recommended. It is not

practical, economical, or feasible, in most

cases. The only situation where fertilization

may be justified would be a small, high-

valued windbreak planted on soils that have

obvious soil nutrient deficiencies. Apply

fertilizer according to soil test results.

Summary

Windbreaks protect crops, soil, and livestock

while also improving air and water quality,

broadening biodiversity, and beautifying the

landscape. One of the keys to the successful

windbreak is recognizing what the landowner

wants to accomplish through its application

on the landscape. The next step is to then

under- stand the properties of a successful

windbreak. And finally, choose species to plant

in the wind- break that will enable it to work as

expected. With a little planning upfront, a

windbreak can provide a variety of benefits

from improving crop production to

maintaining livestock health.

Non-Agroforestry Uses of

Windbreaks

Windbreaks for Homes

Benefits

Windbreaks reduce energy consumption by

reducing air infiltration into buildings resulting

in less heat loss and by reducing the amount of

snow removal from roads and around buildings.

Des

ign Tips

• For wind protection only, the tallest row

needs to be 2-5H (H = planned height of the

tallest row) from the primary area needing

protection.

• However, for wind and snow protection, the

most windward row needs to be 100 to 200

feet from the windward edge of the primary

protection area. The distance between the

area needing protection and the wind- ward

row varies with the amount of space needed

for snow storage.

•

Once this critical distance is met, check to

see if the area needing protection is still in

the 2-5H zone, i.e. a house. Areas and objects

more than 10H from the windbreak will

receive reduced wind protection.

To protect structures, the windbreak

should have a density ranging from 60 to 80

percent during the period requiring

maximum protection. To achieve the mini-

mum level of this density range, plant at

least three rows of trees and shrubs with at

least one row being a conifer.

• Extend the windbreak a minimum of 100

feet past structures needing protection to

accommodate wind turbulence at the end of

the windbreak and end-drifts of snow.

• Locate access roads from 100 to 500 feet

from the ends of the windbreak. If a lane

must cut a windbreak, it should cut through

the windbreak at an angle to prevailing

winds to prevent funneling of wind and

snow drifting.

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Two designs for protecting a structure from

snow

• Traditional multi-row windbreak: A

basic farmstead windbreak consists of

three to eight rows of both conifers and

deciduous trees and shrubs. Conifers or

shrubs should be located on the windward

side with tall deciduous species in the

center. A row of shrubs on the interior or

leeward side completes the design.

• Modified twin-row, high density wind-

break: In areas with frequent heavy snows

consider adding a row or two of shrubs

50 feet to the windward side to trip snow

before it reaches the main windbreak. An

auxiliary planting of shrubs on the leeward

side of the windbreak can also add good

emergency cover for wildlife. This can be

supplemented with a food plot between the

main windbreak and the auxiliary planting.

For more information, visit "Windbreaks

for Rural Living" at

www.nfs.unl.edu/documents/

windbreakruralliving.pdf

Windbreak designs for snow

Community Windbreaks

Planned community windbreaks can provide

extra protection for the entire development and

be an economic gain for the developer and

homeowner from increased property values.

Windbreaks in the rural-urban interface can

also reduce potential conflicts, such as blowing

dust, privacy, odors or noise between land uses.

High quality windbreaks between agriculture

and communities can prevent windblown soil

and snow. Sediment in the yard, dust in homes

and pesticide drift can be great aggravation to

both rural and urban homeowners. For more

information see Working Trees for

Communities,

https://www.fs.usda.gov/nac/documents/wor

kingtrees/brochures/wtc.pdf

Windbreak Design

To Protect Homes and Outbuildings

Windbreaks for protecting structures such as

the farmstead, roads and other buildings:

Position the windbreak as close to

perpendicular to the most troublesome wind

direction. “One-leg” windbreaks are sufficient

if winds come from one direction only, but a

“two-leg” or network of windbreak(s) provides

greater protection for variable wind directions.

Plan for 60-80 % density for maximum

protection. Locate windward row 100 - 200

feet from area needing protection. In areas

with variable winds, multiple-leg windbreaks

provide greater protection to the field or

farmstead than single-leg windbreaks.

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Living Snow Fences

Benefits

Blowing and drifting snow jeopardizes public

safety and emergency services, interrupts

businesses, increases road maintenance costs

and causes wildlife mortality. Living snow fences

are more cost-effective than structural barriers,

can meet many additional objectives, and provide

a wide array of benefits beyond snow control.

Design Tips

• To achieve maximum snow accumulation,

the windbreak density should range from

60 to 80 percent.

• The most windward row should be a

minimum of 100 feet from the area being

protected to prevent inappropriate snow-

drifts. This distance will vary (100 to 300

feet) depending on the location and sever-

ity of winters.

• A trip row of shrubs or dense conifer can

be located 50 to 100 feet windward of the

main windbreak to create a snow trap.

• For protecting roads, allow plenty of room

for the leeward drift by locating the wind-

ward row of the windbreak 200 to 300 feet

from the center of the road.

Below: Integrate windbreaks into an overall landscape

design to achieve multiple objectives.

Refer to the windbreak design for snow figure

for more guidance about snow behavior

adjacent to different windbreak designs.

• Go to Working Trees: Living Snow Fences,

https://www.fs.usda.gov/nac/document

s/workingtrees/brochures/livingsnowfe

nceforweb.pdf, and Windbreaks for Snow

Management, https://nfs.unl.edu/

documents/windbre aksnowmgmt.pdf,

for more information.

Windbreaks for Livestock Odor

Reduction

Benefits

Windbreaks (or vegetative environmental

buffers - VEBs) placed around livestock

production facilities can help mitigate the

movement of odors and dust generated by

these operations. Urban expansion has placed

many more people into closer contact with

agricultural operations. Large scale livestock

confinement production has led to increased

concentrations of odor emissions travelling

across highly modified landscapes relatively

devoid of natural barriers. Windbreaks alone

will not prevent these odor problems but can

help reduce negative visual perceptions and

the detection of smell by neighbors and

surrounding communities.

Design Tips

• Windbreaks should

consist of at least one to three

rows of conifer and

deciduous species.

• Two to three rows of

trees can provide an ideal 60

percent windbreak density

(or 40 percent porosity) for

odor control.

• Shrubs are generally

planted in the outside or

inside rows, followed by

conifers with deciduous

hard- woods towards the

middle or along the

downwind side where they

can grow more efficiently.

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• Tree varieties and placement for the wind-

break should be managed to maximize odor

interception and dilution of air, and reduce

odor leaving the source.

• Where site and facility conditions merit

and allow, place plantings (not necessarily

windbreaks) around the entire perimeter

of the odor source.

• Even a site with a windbreak on one side

that is strategically placed and designed

can make a difference.

• For more information see Windbreaks: A

“Fresh” Tool to Mitigate Odors from

Livestock Production Facilities,

https://lib.dr.iastate.edu/nrem_pubs/163/

Windbreaks for Wildlife Benefits

Benefits

With careful design, windbreaks provide

nesting habitat for a wide variety of birds (up to

57 species) and other wildlife. Windbreaks can

also produce needed food as well as protective

cover when the wildlife forage in adjacent

areas. Shelter from predation and escape cover

as well as emergency cover from severe

weather e.g., blizzards can be provided.

Design Tips

•

Windbreaks can be given a more natural

look and still provide excellent wildlife

habitat and wind protection.

Connecting Habitats - Where appropriate,

select the windbreak site that connects to a

larger habitat block such as a river corridor,

woodlot, wetland, woody draw, or similar

area.

• Herbaceous Cover - Consider planting or

leaving herbaceous vegetation such as a

mixture of grasses and legumes, standing

grain, or crop residues as a border (20 to

50 feet wide) along the edges of the wind-

break. If grasses or legumes are used, they

should be separated from the new tree

planting to avoid competition. This strip

of cover can provide nesting, loafing, and

foraging cover for a number of species.

• Winter Cover - Adding a shrub row 50 to

100 feet windward of the main windbreak

as a snow trap results in greater wildlife

protection on the leeward side of the main

windbreak. Use species that will provide

good thermal protection in the winter such

as cedar and spruce.

• Food - Select species that may have high

food value for a variety of wildlife. Planting

food plots or fruit-bearing shrubs on the lee

side of windbreaks provides food in an area

protected from wind and possibly warmed

by the sun, points that are particularly

important in cold months.

• For more information see Windbreaks and

Wildlife,

https://extensionpubs.unl.edu/

publication/9000016363670/windbreaks-

and-wildlife/

Quail find excellent habitat in field windbreaks.

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Success Stories

Paul Huenfeld, Nebraska Producer Using Wind-

breaks with Organic Farming

“Organic farming and trees were just a natural

fit, like a hand and a glove, as far as I was

concerned. We needed buffers around the farm.

We also really value the importance of habitat

for the insects and the predators, and we see

that along the trees where we can plant grass

and legumes is an excellent source of habitat for

the different species of wildlife.”

Claud Launius, Retired cotton producer, Malden

Plain, Mo.

Claud Launius is a retired cotton farmer in the

sandy soil area of “the Bootheel” of Missouri

known as Malden Plain. “We were having a lot of

trouble with blowing sand in the spring of the

year; it was blowing and hurting our cotton

pretty bad--killing some of it.” Then, Natural

Resources Conservation Service (NRCS)

District Conservationist Phil Gurley told

Launius about crosswind trap strips, and

said he could get switchgrass seed

through the Missouri Department of

Conservation. Launius installed some on an

80-acre field in 1989. Although some cotton

farmers have used wheat and rye to slow the

wind, switchgrass grows to 6 or

8 feet and Launius says it keeps the wind up in

the air. “In the spring, it’s windy when the

cotton plants are babies, and that’s the worst

time. If they get up to 6 or 8 inches tall they can

defend themselves; but when they’re short,

with just two leaves, wind and sand can just cut

them off. It’s like a baby that gets sick--they

don’t grow like they ought to until they get well

again. That’s cotton, it’s like any plant.” When

Launius retired he rented his land, and his ten-

ant has kept up the wind strips.

Launius added four rows of switchgrass in

strips with 24 rows of cotton. He figures he

might have gone with 36 rows of cotton to 4

rows of switchgrass, “but I’d be afraid to tear

any of it up.” Besides, he’s doing better with the

68 acres than he did with the original 80 acres.

“Our yields have increased a half-bale per acre

or more because the plants aren’t getting hurt.

They just sit there and grow; the weather

doesn’t bother them. We really like it.” Launius

is surprised that others aren’t planting

switchgrass wind traps, but thinks they just

don’t want to give up those 4 rows of cotton

ground. He notes that there are other benefits

beyond protecting the cotton plants and

boosting production. “It’s doing really well for

quail and other animals, such as rabbits. By

hiding in the switchgrass, the quail run the

hunters crazy. The grass is really thick and it

keeps get- ting thicker and thicker.” To

maintain it, every other 4-row strip is burned

every other year; that makes the switchgrass

“stool out” more, and then it has millions of

seeds on it –”and that’s what quail and wildlife

like.”

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University of Missouri Center for Agroforestry

Economic Incentives

There are several agencies offering programs

that can be used to establish and maintain

windbreak practices on private land. The USDA

Farm Service Agency (FSA) offers three

programs that may be used for windbreaks

and shelterbelts: the Conservation Reserve

Program (CRP), the Continuous Conservation

Reserve Program (CCRP), and the Conservation

Reserve Enhancement Program (CREP). Each of

these programs is designed to take environ-

mentally sensitive and highly erodible land out

of production by offering a soil rental payment,

a cost-share for the establishment of various

conservation practices and other financial

incentives to landowners who offer to set aside

their land.

Of these three programs, the CCRP program

offers direct benefits to landowners

establishing a windbreak/shelterbelt. CCRP is

a voluntary program that focuses on funding

conservation practices (CP) protecting

environmentally sensitive land. Landowners

with eligible land who wish to enroll that land

in the CCRP may sign- up at any time during

the year. NRCS Standard 380 identifies the

guidelines for establishing a windbreak for the

CCRP. For more information, contact your local

USDA/FSA office.

The USDA/NRCS has four main programs that

offer funds for tree planting and agroforestry.

They are the Environmental Quality Incentives

Program (EQIP), the Wildlife Habitat Incentive

Program (WHIP), and the Conservation

Stewardship Program (CSP). In

conjunction with the funding programs

noted, the USDA/NRCS also provides

technical assistance to landowners who

are interested in conservation planning

and application.

The USDA National Institute of Food

and Agriculture supports the

Sustainable Agriculture Research and

Education (SARE) program. Of the three

funding types available through SARE, only

one, the producer grant, is aimed at the

landowner. Landowners who submit

accepted proposals can receive up to

$15,000 to establish and maintain

the sustainable practice that they propose.

See chart (next page) for a listing of

incentives offered by these federal agencies

or consult the UMCA publication “Funding

Incentives for Agroforestry in Missouri.”

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Additional Resources

Windbreak Resources – USDA National Agroforestry Center

https://www.fs.usda.gov/nac/practices/windbreaks.shtml This page has many windbreak references;

we suggest starting with the 11 publications listed under the Windbreak Series heading starting with

How Windbreaks Work. The Agroforestry Notes also provide some specialized information.

NRCS Windbreak Information

NRCS State Windbreak/Shelterbelt Establishment Practice Standards and Specifications:

https://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/programs/?cid=nrcs144p2_027140

I llinois

Illinois Windbreak Manual – Illinois Department of Conservation, Extension and NRCS:

http://web.extension.illinois.edu/forestry/iwm_complete.pdf

Iowa

Planning Farmstead Windbreaks - Iowa State Extension

https://store.extension.iastate.edu/product/Farmstead-Windbreaks-Planning

Farmstead Windbreaks: Establishment, Care and Maintenance - Iowa State Extension

https://store.extension.iastate.edu/product/Farmstead-Windbreaks-Establishment-Care-and-

Maintenance

Minnesota

University of Minnesota, Morris “Selecting Trees and Shrubs in Windbreaks”

https://morrisonswcd.org//?s=windbreaks

Missouri

Using Windbreaks to Reduce Odors Associated with Livestock Production Facilities – USDA NRCS-MO

– IS- MO380: www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_010805.pdf

Nebraska

Windbreak Design – University of Nebraska Extension NEBGuide G1304:

http://nfs.unl.edu/documents/windbreakdesign.pdf

Wisconsin

Windbreaks: Trees as Technology for Protecting Wisconsin’s Topsoil – University of Wisconsin:

www.cias.wisc.edu/crops-and-livestock/windbreaks-trees-as-technology-for-protecting-wisconsins-

topsoil/

Windbreaks That Work – Wisconsin Department of Natural Resources: dnr.wi.gov/topic/

forestmanagement/ documents/pub/FR-070.pdf

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Additional Resources, cont'd

In Print:

Brandle, J.R., L. Hodges, J. Tyndall, and R.A. Sudmeyer. 2009. IN: North American Agroforestry: An

Integrated Science and Practice (H.E. Garrett, Editor). 2nd Edition. Agronomy Society of America, Madison,

WI. Pp. 75-105

Brandle, J.R., L. Hodges, and B. Wight. 2000. IN: North American Agroforestry: An Integrated Science and

Practice (H.E. Garrett, W.J. Rietveld and R.F. Fisher, ed’s.). Agronomy Society of America, Madison, WI. pp.

79-118.

Brandle, J.R., D.L. Hintz and J.W. Sturrock. 1988. Windbreak Technology. IN: Agriculture, Ecosystems

and Environment, 22/23. Elsevier Science Publishers. Amsterdam, The Netherlands. 598 pp

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University of Missouri Center for Agroforestry

What are the advantages of windbreaks for:

•

Cattle

•

Soil

•

Crops

2. How far from the windbreak will crops benefit with increased yields?

Compare and contrast the uses for single-row and multiple-row windbreaks.

4. When considering whether to use single or multiple row windbreaks, what factors

should be considered?

When deciding between deciduous and coniferous species, what factors will also be

used when writing out the management plan?

Putting in a windbreak will cause a farmer to take acres out of production. How can you

persuade a farmer that putting a windbreak in will be beneficial in the long run?

What financial assistance programs are being funded through state or federal programs

to help landowners with the cost of putting windbreaks up on their property?

A number of features must be analyzed prior to the placement of a windbreak. List four

of these features.

For further thought:

Like any other aspect of agroforestry, windbreaks can provide advantages and

disadvantages to the landowner. How do you work with the landowner to see past the

disadvantages and not focus on the negative?

EXERCISE: REVIEW OF WINDBREAKS

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What are the advantages of windbreaks for cattle, soil and crops?

Pro

perly designed windbreaks have been shown to increase crop yield for a wide variety of

crops. Decreases in wind speed protect downwind crops, decreasing evapotranspiration and

increasing water use efficiency. Decreasing wind speed enhanced soil stability and is the primary

basis for the installation of windbreaks dating back to the Dust Bowl of the 1930’s. During the

winter, cattle use energy to keep warm, increasing their feed requirement. Windbreaks moder-

ate winter temperature extremes, reducing cold stress. Windbreaks also improve calving success

rates.

2. How far from the windbreak will crops benefit with increased yields?

e rule of thumb is that crop yields are improved out to 10-15H.

Compare and contrast the uses for single-row and multiple-row windbreaks.

Sing

le-row deciduous windbreaks are designed to improve snow distribution across a crop field

to improve moisture for early season crop growth. They are also used surrounding orchards to

still the air and improve pollination and/or speed up crop maturation. They may also be used as

a visual screen along roads. Other windbreak applications depend on multiple-rows of decidu-

ous and coniferous trees and shrubs, combined and configured for specific purposes (i.e., crop

production, animal protection, snow fences).

When considering whether to use single or multiple row windbreaks, what factors

should be considered?

The purpose of the windbreak dictates the design.

When deciding between deciduous and coniferous species, what factors will also be

used when writing out the management plan?

Both conifers and deciduous trees bring different attributes to the function of the windbreak.

Deciduous trees are more porous to wind movement, and are less effective in slowing wind

speeds. Conversely, deciduous windbreaks reduce wind velocity further downwind. Conifers

provide much more wind blockage, critical to protect cattle from wind and snow and roads and

buildings from snow buildup.

Putting in a windbreak will cause a farmer to take acres out of production. How can you

persuade a farmer that putting a windbreak in will be beneficial in the long run?

A re

alistic assessment of the farmers’ goals and objectives, coupled with a similar assessment of

the entire farm and cropping system, will lead to the diagnosis that may include establishment

of windbreaks. Evidence of windblown soil erosion and associated crop damage, need for cattle

protection or protection of buildings and roads, may all lead to this diagnosis. Once the diagno-

sis includes windbreaks, the next step is to explore cost share programs that may help to offset

establishment costs. Visits to other landowners that have functioning windbreaks, will be very

effective in addressing farmer concerns.

EXERCISE KEY

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What cost share programs are being funded through state or federal programs to help

landowners with the cost of putting windbreaks up on their property?

IP and CCRP both provide cost share for windbreak installation. (see “Funding Incentives for

Agroforestry in Missouri” for a thorough discussion of available cost share programs).

A number of features must be analyzed prior to the placement of a windbreak. List four

of these features.

ight, density, orientation, length, width, uniformity, cross sectional shape.

EXERCISE KEY, con’t

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University of Missouri Center for Agroforestry

Notes