Windbreaks for Iowa
Windbreaks have been a part of Iowa's forest since settlement.
During the 1930's, establishment of windbreaks for farmstead protection was very intensive; at one time, the goal of the windbreak program was to establish a demonstration windbreak in every township in the state to encourage additional windbreak planting. These windbreaks functioned into the 1960's, when, because of low energy costs and high farmland values, many of them were removed. Renewed interests in windbreaks surfaced during the energy crisis of the 1970's and continues today.
Windbreaks provide many benefits.
Windbreaks reduce wind speeds, control snow drifting and accumulation in farmsteads, provide wildlife habitat, enhance farmstead value, and provide a more pleasant environment. Reduced wind speeds in winter months provide monetary benefits. Homes or confinement buildings require 7 to 25 percent less fuel for heating. Livestock protected by a windbreak are 3-7 percent more efficient in conversion of feed to weight gain. Other benefits of windbreaks are measured in quality of life improvement.
Windbreaks should be properly designed and located for maximum benefits.
Some basis design considerations follow:
- Plant a minimum of three rows; additional rows up to 8-11 rows will improve protection and increase benefits.
- Incorporate conifers as the major tree in the windbreak where soil conditions allow. Deciduous trees are only 5-20 percent as effective as conifers.
- Locate on the north and west site of the property; avoid surrounding the farmstead with a solid barrier of trees.
- Use several different species in the windbreak; plant within rows in blocks to minimize competition caused by different growth rates. For example, one half of the first row could be Norway spruce with the other half blue spruce.
- The distance between all rows should be at least 20 feet; the spacing between trees/shrubs within a row will vary from 4 to 20 feet depending on mature size of the species.
- For optimum wind lift, plant the tallest trees inside and the shortest shrubs on the upwind (north and west) side of the windbreak.
- The inside row of the windbreak should be 50 feet away from the protected site (to minimize snow accumulation) or with wider windbreaks 100 feet from the outside rows. The greatest wind protection will occur closest to the windbreak. Protection becomes minimal at 15 to 20 times the height of the windbreak.
- If snow accumulation is a serious problem, use a double row of shrubs on the outside of the windbreak spaced at least 30-40 feet apart.
- Where possible, take advantage of contours and locate the windbreak uphill from the protected site; height is relative for most wind protection.
The standard L-shaped, square corner windbreak can be modified. Trees can planted in groups instead of rows. Corners can be rounded or merged together. The key for optimum protection is providing wind protection on the NW quadrant.