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Conserve Valuable Soil Moisture With Less Tillage
4/24/2003
Ron F. Meyer
Area
Extension Agent (Agronomy)
Colorado State University
Extension
Golden Plains Area |
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Using no-till or ridge-till can save more than just fuel, labor,
and equipment costs. The savings in soil moisture can be just as important,
especially in a year when soil moisture and precipitation are
limited.
Often, tilled soil will dry to tillage depth. An average silt
loam soil can hold about 2 inches of available water per foot of soil. Tilling
6 inches deep and allowing the soil to dry to the tillage depth could result in
a loss of up to 1 inch of soil moisture with each trip. Shallower tillage, even
row crop cultivation, can still result in moisture losses of about ½
inch. By not tilling or cultivating, when weed pressures are low, moisture
losses can be minimized. New herbicide packages also allow less tillage.
Greater yet are the soil moisture losses from evaporation when tillage
destroys residue cover. Residue mulch reduces evaporation in several ways: by
reducing solar heating of the soil, by reducing drying winds from the soil
surface, by insulating the soil to keep it cooler, and by intercepting some of
the waters as it evaporates. Research has shown that a residue mulch can reduce
water losses from evaporation by as much as 3 inches during the season.
While flattened crop residue makes better mulch, standing residue is
preferred in crop production. Any residue that is standing up and still
anchored to the soil is more effective in keeping the wind off the soil
surface, reducing both wind blown soil losses and the dust storms common in the
spring. In addition, anchored standing residue doesn’t have to be cut or
handled during subsequent field operations and is far less likely to move with
the wind, or with surface water runoff. Unlike a flattened mat of residue,
which may keep the soil surface too cold and wet for planting, air movement
among the standing residue allows timelier field operations while maintaining
the benefits of residue.
Some say the soil needs to be tilled to
“open it up to let water in”. Unfortunately soil dries to the depth
of tillage so the initial water let into the soil just replaces what was lost,
rather than adding to the soil moisture reserve. Tillage also breaks up and
pulverizes the soil surface, making the soil prone to crusting from raindrop
impact.
Higher fuel costs this year also are a factor when considering
tillage. By switching to no-till or reduced-till, fuel use decreases and soil
moisture is held in place.
Source:
Paul Jasa, Extension
Engineer
University of Nebraska |
Page Created and Maintained by: Perry D. Brewer, Area
Extension Agent (Technology Education/Youth)
4/29/2003 |
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State University, U.S. Department of Agriculture, Kit Carson, Phillips,
Washington and Yuma counties cooperating. Extension programs are
available to all without discrimination. Where trade names are used, no
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