DESCRIPTIONS OF AGROFORESTRY PRACTICES IN MINNESOTA

Six agroforestry practices are commonly used in Minnesota: windbreaks, silvopastoral systems, forested riparian buffers, forest farming, alleycropping, and achieving whole farm diversification with trees and shrubs. All of these practices combine environmental protection with sustainable and profitable production.

Windbreaks (Field, Farmstead and Community Windbreaks, Living Snow Fences, and Timberbelts)

Windbreaks are plantings of single or multiple rows of trees or shrubs in farm fields to minimize negative impacts from excessive wind. There are a variety of agroforestry practices that fit this description, for example, field windbreaks protect wind-sensitive crops, control wind erosion, provide wildlife habitat and travel corridors, and increase crop yields. Farmstead windbreaks protect farmsteads from driving wind, snow, dust, pesticide drift, and noise. Community windbreaks provide wind and snow protection and recreational opportunities for small towns and neighborhoods.

Windbreaks can also function as living snow fences to capture and disperse snow more evenly across cropland and prevent drifting over roads and driveways. Shrubs used in living snow fences and windbreaks can include species that produce saleable products, such as wild plum, pussy willow, corkscrew willow, yellow twig and red osier dogwoods, hazelnuts, elderberry, chokecherry, nanking and sand cherries, and many others. All of these plants produce products in demand by the food and floral industries, providing producers with additional sources of income as well as environmental benefits.

Timberbelts are a very new and exciting technology borrowed from New Zealand. Timberbelts are multiple row windbreaks that are planted with commercially valuable trees for eventually harvest for wood products (timber and pulpwood). Timberbelts work doubly hard for the farmer, producing saleable wood products while protecting crops from wind damage and stress and increasing yields.

Forested Riparian Buffers

Riparian buffers consist of strips of perennial vegetation (tree/shrub/grass) planted between crop or pastureland and streams, lakes, wetlands, ponds, or drainage ditches. Riparian buffers reduce runoff and non-point source pollution from agricultural activities on adjacent lands by trapping sediment, filtering excess nutrients, and intercepting and degrading pesticides. They can also stabilize streambanks, protect floodplains and flood control structures (as "waterbreaks"), enhance wildlife habitat, and provide a harvestable and saleable product such as timber and pulpwood, fruits, nuts, floral products, etc. Forested riparian buffers qualify for the Conservation Reserve Program Continuous Sign-Up cost-share and annual land rental payments.

Forest Farming

This practice produces commercially valuable specialty forest crops under a canopy of trees. These crops are sold for medicinal, ornamental handicraft, or culinary uses. Shade tolerant crops such as ginseng, golden seal, wintergreen, bloodroot, mayapples, decorative ferns, balsam boughs, shiitake and morel mushrooms, birch bark, as well as fruit and nut crops are intensively cultivated under a forest cover that has been modified to provide the correct level of shade. Specialty products can also be produced in other agroforestry systems such as windbreaks and forested riparian buffers. Markets exist for many of these products, though they may be of a niche nature that may be difficult to access by the newcomer. Depending on the crop and the production and marketing skills of the landowner, forest farming can provide considerable annual/regular income either before, or as an alternative to, harvesting the trees for wood products.

Silvopasture

This practice combines trees with forage (pasture or hay) and livestock production. The trees provide shade and wind shelter for grazing livestock, and can provide additional income when the trees (or tree products) are harvested. Trees and shrubs in silvopastoral systems can also trap and better distribute snow across the fields, minimizing winter injury to forages, and improving groundwater recharge and water availability in drier areas. Some nut and fruit orchards may also be grazed or hayed to produce income before the trees begin bearing. Silvopasture is different from traditional forest or range management because it is intentionally created and intensively managed.

Alley Cropping /Tree Intercropping

Alley cropping combines trees, planted in widely spaced single or grouped rows, with adjacent agricultural or horticultural crops cultivated in the wide alleys between the trees. High-value hardwoods such as oak, walnut, and ash, or fast growing species such as hybrid poplar are potential species for ally cropping systems. Annual crops (e.g., row crops, forages and vegetables) cultivated between rows of nut or fruit trees (e.g., black walnut) provide extra income before the trees come into bearing and early in the long-term timber rotation. Alley cropping provides an opportunity to convert marginal cropland to woodland, while continuing to earn income from annual crops during the first years of the planting.

Whole Farm Diversification with Woody Crops

Farm diversification requires that we take a holistic, landscape view. Diversifying a farm with woody crops involves intentionally integrating trees into the farming system using practices that are designed specifically for the conditions and needs of a specific piece of land. Such plantings meet the "4-I's" criteria for agroforestry, but on a larger, landscape scale. For example, converting 40 acres of marginal agricultural land to a hybrid poplar, hazelnut, or Christmas tree plantation introduces trees and shrubs into the whole farm system. These woody perennials enhance biodiversity, diversify producer income sources as well as risk, may generate greater profits than annual crops, and create a more integrated, interesting, and visually appealing land use system that is environmentally, economically, and socially sustainable.

diversified sources of income and less risk profits from valuable specialty crops and forest products such as timber, firewood, fruit and nuts, forage, and craft supplies higher product quality (reduced wind damage and abrasion from blowing soil) increased crop yields by up to 15% over the entire field, including the area occupied by windbreaks1 better livestock protection, production, and survival, with up to 10% increased weight gains, and improved milk production by 8-20%2 reduced irrigation needs, from 3-22%3 increased property values from 6-12% in the urban fringe simply by having trees and shrubs3 improved financial returns from on-farm value-added activities reduced ditch cleaning and snow removal costs lower (up to 30%) farmstead heating and cooling bills1 less soil loss from wind erosion (by 50-100%)3

¹"Conservation Trees for Your Farm, Family, and Future" by the National Arbor Day Foundation"
²"Agroforestry: Working Trees for Agriculture" published by the USDA Forest Service
³Windbreak Technology: Economics of Windbreaks, NRCS, 1997. pp 13-3

better ability to "harvest" water through improved snow management less blowing soil, dust, and odors, and a 10-20% reduction in noise1 improved water quality—vegetation acts as a natural filter and reduces stream-bank erosion, sediment, and chemical/nutrient inputs improved game and non-game fish and wildlife habitat greater biological and aesthetic diversity increased recreational and hunting opportunities

¹ Windbreak Technology: Economics of Windbreaks, NRCS, 1997. p 13-3

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