18. Install Terraces |
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Long
slopes give runoff water a chance to build up momentum and energy,
increasing its power to slice into the land. One of the best ways
to shorten long slopes is with terraces.
Terraces are embankments, channels, or combinations of embankments
and channels constructed across a field slope. They channel runoff
water into a stable outlet, where it is carried safely away.
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Some
terraces have a grassed waterway outlet. . . |
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. . while other terraces channel runoff water to a storage section
where it is released slowly through a surface inlet and underground
pipe or tile. |
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There
are three basic types of terraces. With the broad-base terrace, all
slopes are designed to be farmed. These terraces are used on long,
uniform, gentle slopes up to 5 or 6 percent. Because the entire terrace
can be farmed, make sure the terrace slopes are not too steep for
your equipment. |
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With
a grassed-back-slope terrace, the back slope is graded to a steep
pitch and grassed. The front slope, which is farmed, is flattened
and is usually the width of your planter. Consider grassed-back-slope
terraces on slopes of 6 to 15 percent. |
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With
narrow-based terraces, the entire ridge is grassed instead of just
the back slope. The ridge is narrow, so only a small area of the field
is removed from production. Narrow-based terraces disturb less soil
than the other two types of terraces; therefore, they are often the
best choice when topsoil is shallow and subsoils less productive. |
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