Emergency control strategies may be needed to control soil erosion this winter
February 23, 2010
Soil erosion has been very obvious this past month, due to many circumstances.
High winds lasting several days combined with longer term environmental conditions to cause a “perfect storm.” The 2009 crop year was cooler and wetter than normal. This resulted in:
· a delayed start and prolonged planting season,
· a longer growing season (almost a month behind by September) due to the slower accumulation of growing degree days,
· a delayed start of harvests, and
· a prolonged harvest season.
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All these factors delayed or prevented farmers from performing final operations to reduce or eliminate wind erosion through the winter. This includes roughing or ridging the ground or planting a winter annual crop like wheat with a goal of getting enough ground cover to prevent wind erosion.
The two-day windy blizzard at Christmas added to the concern. One day of wind is unusual, but two days and nights is even less common – and the winter season had just begun. Unfortunately, the storms returned and worsened the weekend of January 24-25 with gusts at Sidney measured over 60 mph. Wheat is in a passive or dormant state, and cannot recover to produce ground cover until it warms up.
Although soil erosion is best handled with a long-range plan that includes maintaining vegetative ground cover, reducing field widths, and planting wind breaks, when soil starts moving unexpectedly, or conditions suggest this may occur, emergency control strategies are needed. The following emergency control methods are available to reduce damage from wind-induced soil erosion that already has started or is anticipated:
· tillage to produce ridges and clods;
· addition of crop residue;
· application of livestock manure;
· irrigation to increase soil moisture;
· temporary, artificial wind barriers;
· and soil additives or spray-on adhesives.
The choice of method, or combination of methods, depends on severity of erosion, soil type, soil moisture, type of crop, stage of crop growth, and equipment or materials available.
Tillage is a commonly used method for emergency wind erosion control, but it should be viewed as a last resort, although it can be effective if done properly.
The purpose of emergency tillage is to provide a rough, ridged, cloddy surface more resistant to wind erosion. Surface roughness reduces wind velocity at the soil surface and helps trap windblown soil particles. Emergency tillage is only a temporary measure because clods readily disintegrate.
Where possible, use emergency tillage before soil blowing starts. Soil erodes more rapidly from abrasion by windblown soil particles than from wind that contains no soil particles. If erosion is anticipated because high winds are forecast, start emergency tillage on areas of the field most vulnerable to erosion before the wind reaches a critical speed. If soil blowing already has started, begin emergency tillage on the upwind edge of the eroding area. Tillage in a direction perpendicular to the expected wind direction is most effective.
An implement used for emergency wind erosion control should gently lift the soil, creating as many and as large of clods as possible. Disks and harrow-type implements with several ranks of closely spaced tines generally will not be effective, and should not be used.
For more information about the details of equipment types and operations, contact your local Extension office.
Emergency tillage can be used in a field planted to winter wheat. If wind erosion occurs, it is better to control the damage early using emergency tillage, rather than risk losing the entire crop. Use narrow chisel points spaced 4 to 6 feet apart, 4 to 6 inches deep. Tillage direction should be perpendicular or at an angle to the wheat row to minimize plant injury.
Before beginning emergency tillage operations, producers should check with their crop insurance agent.
Data from a five-year study at two sites in Kansas suggests this type of emergency tillage has minimal effect on potential yield, but can reduce the damage to growing wheat and can reduce soil loss in moderate erosion situations. This study found emergency tillage caused the most damage to wheat yields when the wheat had just emerged. The least yield reduction was found when the tillage was done in fields with wheat plants already tillered. Emergency tillage is not effective if clods cannot be brought to the surface, and is not possible after the soil has frozen more than 2 inches deep.
Drew Lyon is extension dryland cropping system specialist at the UNL Panhandle Research and Extension Center. Bill Booker and Karen Deboer are Extension Educators. John Smith is Machinery Systems Engineer.