"Harmony with land is like harmony with a friend; you cannot cherish his right hand and chop off his left. That is to say, you cannot love game and hate predators; you cannot conserve the waters and waste the ranges; you cannot build the forest and mine the farm." Aldo Leopold

David Countryman, ISU Forestry (retired)
Graduate Research Assistant:  John C. Murrow

Many highly erodible acres in and out of the Conservation Reserve Program could potentially meet conservation compliance standards by applying the practice of contour tree buffer strips.

To apply contour tree buffer strips to a specific area, rowcrop strips are established and maintained as parallel, contour strips that contain no pointrows when farmed with standard farm equipment. The width of these parallel strips are determined by machinery width and maximum slope distance of rowcrop allowable to control soil erosion. Between the strips of rowcrop are strips of grass with contour rows of trees. The tree strips vary in width to accommodate the natural lay of the land. 

Schematic of contour tree buffer strips.

This practice has many advantages. Soil erosion is reduced from rowcropping the entire slope. Because the rowcrop strips are wide enough that trees do not close them over, rowcrops are permanently maintained in the strips to provide an annual income from the property. Weak terraces tend to form as the grass and tree strips filter sediment eroded from the rowcrop strips. The tree strips also provide wildlife corridors and aesthetic diversity in the area. Mixing conifers in the tree strips provides winter thermal cover for wildlife and provides training trees for high value hardwoods. Planting high-value hardwoods in the tree strips provides long-term economic gains from the sale of sawlogs and veneer while the agricultural crops provide an annual income.

Strip cropping area. Trees not yet visible in grassy areas.

Preventing erosion by keeping soil at the production site on sloping land, prevents nonpoint pollution in streams and lakes caused by soil particles and associated chemicals. The result is a more sustainable and environmentally sound food and fiber production system.

Economic Analysis of Contour Tree Buffer Strips Using Present Net Value
An economic analysis compared contour tree buffer strips with rowcropping, terracing, conventional tillage, contour strip-cropping, and the Conservation Reserve Program.  Four tree species were analyzed:  Black walnut, Red oak, White oak, and ash.  Sensitivity analyses were carried out on land values, real interest rates, and the projected costs and revenues associated with different scenarios.

Without subsidies, contour tree buffer are economically competitive with all practices evaluated except:

• tree plantations at $1,183 per hectare land value.
• row cropping at $2,223 per hectare land value.
• strip-cropping at $3,263 per hectare land value.

Land owners who have one or more of the following problems and/or goals should consider the contour tree buffer system as an additional alternative:

• Land that is highly erodible.
• Land that is of low value.
• Land that has low crop yields.
• Landowners who have high land stewardship values.
• Landowners with long range investment objectives.
• Landowners who want to improve water quality.
• Landowners who want to add diversity to the landscape and provide areas for wildlife.