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2. Soil Fundamentals
Compaction
Compaction restricts the movement of
water and air so there is both reduced
water infiltration and reduced drainage. In a
compact soil, pores between soil particles
are generally micropores; roots will not
grow well and water is held tightly. As a
consequence, there is generally a less healthy
soil microbiome.
In New Mexico and Colorado, compaction
can be an issue for wet soils rich in clay.
Dry sandy soils are not as vulnerable to
compaction, based on their moisture and
texture. Good soil structure (aggregation)
and vegetation cover can also help prevent
compaction. In this context, soils in New
Mexico and Colorado are vulnerable to
compaction, as some lack good aggregation
due to naturally low organic matter and clay
content, and to sparse vegetation cover.
Either a penetrometer or a shovel can be
used to identify a compacted soil layer. It is
important to conduct a penetrometer test
when the soil is at field capacity (see P43), as
the reading on the penetrometer increases as
the soil dries. You can also gauge compaction
by knowing your soil texture, bulk density, and
infiltration rate. A compacted soil layer will
have few or no roots and will often appear
smooth and shiny when cut through.
(For further information about terms and
concepts in this paragraph, see “Soil water
component,” below.)
Glossary
Compaction
the term for limited soil pore space caused
when soil aggregates are pushed together
or degraded.