Synopsis:
Wind erosion control is typically needed in areas with low and variable precipitation and frequent droughts, and where high winds, high temperature and consequent high evaporation are common conditions, such as in southern Alberta. Potential average annual erosion rates from wind erosion are predicted using the wind erosion equation E= f(I, K, C, L, V) where I is the soil erodibility index, K is the soil-ridge-roughness factor, C is the climactic factor, L is the unsheltered, weighted travel distance of the wind across a field and V is the equivalent vegetated cover. Wind erosion can be controlled with one or more of the following five basic principles of wind erosion control:
· Reduce field widths along the prevailing wind direction by strip cropping or establishing wind barriers and thereby reducing wind velocity and avalanching
· Establish and maintain vegetation or vegetative residues to protect the soil
· Produce, or bring to the soil surface, stable aggregates or clods large enough to resist the wind force;
· Roughen the land surface (as with furrows) to reduce the wind velocity and trap drifting soils
· Level or bench land to reduce effective field widths and erosions rates on slopes and hilltops where converging streamlines of windflow cause increased velocity and wind force.
Windbreaks and wind barriers contribute to wind erosion control by reducing windspeed on their leeward side and by decreasing field length in the erosive wind direction. If trees are used as a windbreak, single row plantings are common and are as effective and use less land than multiple row plantings. Erosion protection is thought to extend to 10 times the height of the tree species used as a windbreak. Perennial grass barriers are also effective for controlling wind erosion, trapping snow and reducing evaporation on dryland cropping areas. Data presented in the paper suggests a maximum distance between perennial grass barriers of 9m if barriers are oriented perpendicular to the erosive wind force. Strip cropping is another effective method to control wind erosion. It is accomplished by dividing a field into narrow strip where strips of erosion resistant crops or standing stubble are alternated with other crops or unprotected fallow fields. Width of strips depends on soil texture and varies from 6m for sand to 131m for silty clay loam. Other windbreaks and windbarriers include artificial barriers such as snow fencing, board walls, earthen banks, and rock walls are used for wind erosion control but on a limited basis due to high cost for materials and labour.
Conclusions:
Windbreaks and windbarriers contribute to wind erosion control by reducing windspeed on their leeward side and by decreasing field length in the erosive wind direction. If trees are used as a windbreak, single row plantings are common and are as effective and use less land than multiple row plantings
Thresholds/Learnings:
If trees are used as a windbreak, single row plantings are common and are as effective and use less land than multiple row plantings. Erosion protection is thought to extend to 10 times the height of the tree species used as a windbreak
