by

Charles R. Fenster and Ron Gaddis

Crop Management Specialist and Conservation Engineer. respectively, Nebraska cooperative Extension Service. Reprinted with permission.

CAUSES OF WIND EROSION

Unprotected soil is subject to wind erosion. Any occurrence that leaves the soil bare sets the stage for soil movement.

Wind erosion is caused by a strong, turbulent wind blowing across an unprotected soil surface that is smooth, loose, dry and finely granulated. Very fine particles can simply be suspended in the air stream and carried long distances. Slightly larger soil particles may hop along the surface-now in suspension, now dropping to the ground. Still larger particles are rolled along the soil surface. Loose soil particles can drift along, bombarding and dislodging still more particles with the same effect as sand blasting.

Unprotected soil surtlaces can result from the removal of plant materials after harvest of crops such as sugar beets, field beans and potatoes and from bare grain and fallow fields. Land that is recently leveled is especially vulnerable to wind erosion, as is overgrazed rangeland. The removal of crop residue for feed as well as shelterbelt removal have led to serious wind erosion in a number of areas. Marginal acres put into cropland in regions of low rainfall contribute to ideal wind erosion conditions.

AN OUNCE OF PREVENTION

The most effective control of wind and water erosion is to maintain cover on the soil surfacethroughout the year, especially during those periods when winds are apt to be dry and of high velocity. Increasing surface roughness and maintaining clods on the soil surface of cultivated land is at best only a temporary measure. More permanent control measures include strip cropping or maintaining a cover of residue and plant growth on the entire soil surface. Use of stubble mulch, reduced tillage and other management methods minimize wind erosion.

Each tillage operation causes some loss of soil moisture and residue. The need for weed control sometimes causes farmers to till or cultivate the field until niost of the residues are dissipated. The use of subsurface tillage tools and other reduced tillage practices will control many of the weeds without destroying a large amount of the residue. However, under wet and cool conditions, weed control can be difficult with subsurface tillage Many broadleaf weeds can be controlled with a timely application of herbicides.

Strip cropping, employing narrow strips, is effective in the sandy areas of the state to inhibit wind erosion. The best protection against wind erosion is a good protective cover to growing plants or residues. If no cover exists, farmers have no choice except emergency control by using tillage or mulching.

A POUND OF TEMPORARY CURE?

Once soil drifting has started, it is difficult to completely stop the damage. On the other hand, prompt action may prevent a small blow spot from damaging the entire field or other fields.

'Mulching. Wind erosion can be controlled by mulching with manure or plant material such as straw, hay, corn or sorghum stalks. About 2,500 pounds of plant residue per acre is needed to control areas which already have considerable wind erosion.

Residues can be spread by hand, manure spreader or power box. Distributing one half bale of straw every 20 feet will give adequate residue coverage. A mulch treader or rotary hoe will help spread the residues uniformly. Straw residues can be anchored with a stubble puncher or disc set straight. Redrilling (with seed if time of year is right) or using a chisel plow with chisels spaced about 30 Inches apart can also be used to anchor residues.

The residues should be anchored at right angles to the prevailing winds. A north-south orientation is suitable In Montana where prevailing winds are from the west or heavy manure will generally hold without anchoring. Emergency tillage is a last resort method, though it can be effective if carried out properly. The purpose of emergency tillage is to provide 2 roughened, cloddy surface resistant to wind erosion. Surface roughness reduces the wind velocity at the surface and provides traps to catch the windblown soil particles.

Chisels are the most common type of tool to roughen the soil and bring clods to the surface. In growing wheat, 2-inch chisels spaced 3 feet apart 2nd operated 4 to 6 inches deep will usually bring sufficient clods to the surface to reduce wind erosion. This operation frequently saves the wheat. However, if the whe-it is destroyed or on bare ground, chisels 4 to 6 inches wide, spaced 30 inches apart and operated at a depth of4 to 5 inches is generally effective in stopping erosion. This operation brings clods to the surface and creates a rough surface on medium and fine textured soils. Loose, sandy soils require a different type of tillage More drastic measures are needed 2nd the resulting surface roughness is more short lived. A moldboard lister spaced 40 to 50 inches apart may be needed to obtain sufficient clods and surface roughness. The first listing should be shallow-not more than 4 to 5 inches in depth. Later listings, if necessary, should be progressively deeper. One can split the middle~or work In the old furrows. All operations should be carried outacross the direction of the prevailing wind. Some other pointers:

1. A sufficient area upwind should be tilled-not just the presently blowing area.

2. For row crops it may be necessary to compromise by following the row pattern Instead of the prevailing winds. If some old crop stubble remains, the emergency tillage tool should be used between the old rows to leave as much stubble in the rows as possible.

3. The tractor speed and running depth should be varied as needed to bring clods up from the furrows. The best clods come from moist soil.

Remember, the best way to controlling wind erosion is maintaining a protective cover of growing plants or crop residues on the soil surface.