Soil Biology & Ecology
Part 2 – 118 | Unit 2.3
Assessment Questions Key
Assessment Questions Key
- What is soil?
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minerals (sand, silt, clay, and nutrients), pore
spaces, water, gases, organic matter, living
organisms, and plants
- What forms of life exist in soil ecosystems?
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isopods, mollusks, insects, insect larvae,
worms and many small vertebrate animals
such as gophers, ground squirrels, moles, etc.
- How would you define a “healthy” agricultural
soil?
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chemical properties which has the capacity
to sustain biological productivity, maintain
environmental quality, and promote plant,
animal, and human health. This would
include many of the following general
characteristics:
a) adequate rooting depth for the crop(s) to be
grown
b) a 3–5% organic matter content
c) maintains stable soil aggregates
d) allows for rapid water infiltration without
soil erosion
e) a low bulk density (good structure with
minimal compaction)
f) pH between 6 and 7
g) an extractable nutrient profile within the
optimal range of physiological tolerance for
the crops to be grown
h) good water holing capacity and well-drained
i) high soil biological diversity and activity (soil
respiration)
j) adequate supplies of labile organic matter
with potentially mineralizable nitrogen
k) seasonal soil temperatures from 60–85ºF
4) What is a soil food web?
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(producers, consumers and decomposers)
in a soil ecosystem interacting among and
between trophic levels5) What might be some negative effects of
the long-term practice of monoculture
cropping and the use of synthetic chemical
fertilizer and pest control agents on the soil
ecosystem?
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reduction in nutrient- and water-holding
capacity, reduction in soil biological diversity
and activity, increased pest and disease
incidence