Increasing crop yield with shelterbelts

If there was a way to improve your crop yields while also protecting your farmyard from harsh winds, would you be interested?

If the answer is yes, then the solution is to start planting rows of trees, known as shelterbelts, around your home.

Crop yield increases in fields adjacent to shelterbelts have been reported in many studies. These increases occur because of reduced wind erosion of topsoil and wind damage to crops, improved microclimates and better snow (moisture) retention.

"Studies from Saskatchewan, Manitoba, and North and South Dakota reveal that fields protected by mature shelterbelts develop an average yield increase of three and a half per cent for wheat and up to six and a half per cent for alfalfa," explained Laura Poppy, shelterbelt specialist with Agriculture and Agri-Food Canada's (AAFCs) Shelterbelt Centre in Indian Head, SK.

"These figures include land taken out of production for shelterbelt planting and the competition of the shelterbelt with the crop, two factors which can partially offset gains in yield," Poppy continued. "Percentage yield increases due to shelterbelts are usually higher in drier regions or in drier years as well. Yield increases can be optimized by the selection of appropriate tree species, good shelterbelt design and maintenance, and the use of responsive crops."

Poppy said that mature shelterbelts should occupy less than five per cent of the total field area. Land requirements can be minimized by selecting tree species with upright, narrow growth, such as green ash. These trees give the most protection relative to the area of land occupied. If sprawling shelterbelts are already present, the overhanging branches can be pruned to limit land occupation.

Competition from tree roots with adjacent crops can be reduced by avoiding tree species with extensive, shallow root systems. Green ash, caragana, pine and Siberian larch are relatively noncompetitive, while poplar is more so. Competition can also be minimized by regularly cutting roots (root pruning) at a distance from the shelterbelt of approximately the height of the tree, to a depth of 60 cm.

"The primary purpose of the shelterbelt must be determined before it is designed," Poppy explained. "Ideally, shelterbelts should trap snow in wide, shallow drifts, reduce soil erosion and create a microclimate that increases crop yield. Very porous shelterbelts are required for even snow trapment, while denser belts are necessary for effective reduction of erosion and to create a better microclimate. Generally, tall, long-lived trees planted in rows perpendicular to prevailing winds and combined with fields that are narrow can be expected to provide the greatest yield increases."

Crops differ in their responsiveness to shelter. Winter wheat, barley, rye, alfalfa and hay are highly responsive to protection, while spring wheat, oats and corn respond to a lesser degree. By combining proper tree species selection, good shelterbelt maintenance and responsive crops, shelterbelts can be expected to improve yields and increase profits.

The Shelterbelt Centre works in partnership with industry to make Canada the world leader in food safety, environmental stewardship, research and innovation. The CCAF supports the goals of Agriculture and Agri-Food Canada's Agricultural Policy Framework (APF), which puts the necessary programs in place to bring long-term security and sustainability to Canada's agricultural sector.