Author
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Van Donk, Simon |
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Submitted to: Meeting Proceedings
Publication Type: Other Publication Acceptance Date: 5/25/2004 Publication Date: 6/3/2004 Citation: Van Donk, S.J. 2004. Wind erosion control. Proceedings of 2004 Spring Field Day, Kansas State University Northwest Extension Center, Colby, Kansas. p.22-24. Interpretive Summary: Technical Abstract: Wind erosion can be controlled by reducing the wind at the soil surface or by creating surface conditions that are more resistant to the wind. Control can be accomplished by maintaining vegetative residue on the soil surface, employing barriers and strip cropping, utilizing stable soil aggregates, roughing of the land surface and reshaping the land. Conditions are conducive to wind erosion when the soil surface is smooth, loose, dry and finely granulated, when vegetative cover is sparse or absent, and when the susceptible area is large. Wind erosion control is usually needed in areas with low and variable precipitation and frequent droughts, and where high winds prevail. Erosion control is not only needed to conserve soil but also to protect crops that are easily damaged by moving soil particles. Vegetation or vegetative residue to protect the soil The importance of vegetative protection on the land cannot be overemphasized. On unprotected fallow fields, vegetative cover can best be maintained by practicing no-till or stubble-mulch farming. Stubble mulching is a form of subsurface conservation tillage where the soil is tilled without inversion. Tillage tools, such as chisels, field cultivators, sweeps or blades, are used. Weeds are controlled with cultivation and/or herbicides. The level of protection provided by stubble mulching is proportional to the kind, quantity and orientation of crop residue maintained on the soil surface. Excessive use of tillage implements that bury crop residue are the major cause of inadequate vegetative cover for erosion control on cropland. Also, tillage operations that flatten crop residue must be minimized. Standing residue is 5 to 10 times more effective in controlling wind erosion than flat residue. No-till farming has increased significantly in the United States in the past few decades. With no-till a crop is planted directly into a seedbed that has not been tilled since the harvest of the previous crop. Only the immediate seed zone is disturbed and no additional tillage occurs. Many studies have shown that a no-till program virtually eliminates erosion problems. No-till producers in eastern Colorado and southwestern Nebraska assert that wind erosion is zero on their fields. A cover crop produces vegetative protection against wind and water erosion. Cover crops are usually planted when protective residue is inadequate and winter and spring winds are high. Cover crops are also planted between rows to provide protection for vegetable or other crops that are highly susceptible to abrasive injury in the seedling stage. Cover crops are best suited to humid and higher rainfall areas or irrigated land. In many of the semiarid and arid areas of the Great Plains, cover crops are not practical because they compete for limited soil moisture. Generally, cover crops are used in these dry non-irrigated areas only to control erosion on erosion-susceptible knolls or where low residue crops have been grown. Barriers, strip cropping, etc. Windbreaks and wind barriers contribute to wind erosion control by reducing windspeed, mostly on their leeward side. They decrease the field length along the erosive wind direction. The main effect of reducing downwind field length is a reduction in breakdown of clods and crust by abrasion from saltating (hopping) particles. The effect of any barrier in reducing the rate of soil movement depends on the wind velocity and direction, the threshold velocities needed to initiate soil movement, and the barrier shape, width, height and porosity. For planning purposes, the distance of 10 barrier heights has been widely accepted as the minimum protected area on the leeward side of barriers. The rate of soil movement by wind is proportional to the cube of the wind speed above the threshold. Consequently, a small decrease in wind speed could still result in a signific |
