Cropping method holds potential for cattle, trees


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Posted: 7/16/2009


It is common in Mississippi to see cattle grazing in pastures surrounded by trees, but researchers at Mississippi State University are looking into the feasibility of bringing it all into one field.

The goal of silvopasture systems is to use space and the growing season more effectively by combining trees or shrubs with forage and livestock production in the same acreage.

Rocky Lemus, MSU Extension Service forage specialist, said the system could become the predominate forestry practice in the state and the Southeast. One of the benefits of silvopasture is its flexibility.

"A producer could have pastures where trees and shrubs can be added or timberland where forages can be added," Lemus said. "In some cases, land on which neither exists in sufficient quantity to meet the land-use objective can be moved into a silvopasture system. Silvopasture can improve the overall economic performance of a farm enterprise by diversification."

Lemus said most commercially grown pines—loblolly, slash and long leaf varieties—are suitable for silvopasture systems. In addition to providing timber income to the landowner, these trees give wind protection and shade for livestock.

Many livestock owners who implement silvopasture systems use forages such as tall fescue, bahiagrass and Bermudagrass.

"Forage should be selected based on suitability for grazing, compatibility with the site characteristics and performance in the shade," Lemus said. "Some legumes, such as clover or vetch, can be incorporated in this system."

Livestock grazing should be closely managed in silvopasture systems. Grazing should not be allowed until the trees are tall enough and strong enough not to be damaged by the livestock. Many producers use the land between trees for hay production.

Henry Gordon is an MSU graduate assistant in forestry who has an agroforestry research project at the North Mississippi Branch Experiment Station in Holly Springs.

"We are growing these crops in research plots to determine their growth response in association with the pines," Gordon said.

He is working on an alley cropping system growing loblolly and short-leaf pine in rows, with either clover or soybeans, corn, milo or switchgrass in the alleys between trees. The trees are planted in either two rows or four rows with a 40-foot alley between sets of trees.

"Data shows that agroforestry plantings are probably more profitable over time than a regular forest plantation because with the crops grown in the alleys, you are making more money in between timber harvests than you would just by thinning the trees," Gordon said. "We’re working now to figure out what crops work best in these systems so people in Mississippi can use these silvopasture and agroforestry systems."

Other benefits of agroforestry systems include reduced runoff and erosion, improved water quality and nutrient cycling. These benefits can make the system more profitable by lowering inputs such as fertilizer into the system, increasing revenues from hunting leases and lowering environmental impacts.

Glenn Hughes, Extension forestry specialist, said there are opportunities in Mississippi for successful silvopasture, but he is interested in learning more about the quality of the timber produced in these situations.

"You can produce a lot of wood in a silvopasture system, but with the trees spaced very far apart, they can grow too fast for high-quality saw timber," Hughes said. "When trees grow closer together, the wood is stronger and more dense. The challenge for silvopasture is not in producing the maximum volume but in producing good-quality timber."

Saw timber is the high-value, desired product of pine tree production, and what cannot be sold as saw timber is marketed as pulpwood.

Hughes said foresters typically like to see a pine tree with four growth rings per inch for high-quality lumber. He has seen some trees grown in silvopasture settings that were 15 years old and 18 inches in diameter.

"Normally we try to speed up tree growth, but the question to me is, ‘What can we do to slow down the growth of our trees in this system?’" Hughes said.