Download The Soil Food Web Seasonal Microbial Activity

'-,
The Soil Food Web
Arthropods
Predators
Birds
Nematodes
Fungal- and
1 101
bacterial-feeders
Fungi
Mycorrhizal fungi
Saprophytic fungi
Plants
Shoots and
roots
Protozoa
Organic
Matter
Amoebae, flagellates,
and ciliates
o
Waste, residue and
metabolites from
Animals
Bacteria
plants, animals and
microbes.
I
First trophic level :
Second trophic level :
Third trophic level :
Fourth trophic level :
Photosynthesizers
Decomposers Mutualists
Pathogens, Parasites
Root-feeders
Shredders
Predators
Grazers
Higher level predators
Fifth and higher
trophic levels :
Higher level predators
Composting is a
Seasonal Microbial Activity
great way to "see"
soil organisms in
V
a
early
summer
Q
o
action, breaking
~ °
_
down manure on
,a
C
0)
v
d
v
\
late
summer
\
first
frost
last
frost
the farm or leaves
in the yard .
V
M
S:
January
Month
December
FIGURE 2-13
The rhizosphere . The mucigel is a mixture of gelatinous and other plant products, bacterial cells and;
their metabolic products, colloidal minerals, and organic matter, which together with other plant
exudates, lysates, and secretions form a gradient of carbon that is most concentrated near the root
surface and decreases with increasing distance away from the root . Because of this gradient, the
rhizosphere is a zone of intense microbial activity . Original drawing by Kim Luoma .
FIGURE 1-1
A soil habitat containing mineral soil particles (sand-Sa, silt-Si, and clay-C), organic matter (OM), water (W), plant
root with root hairs (R), and soil organisms (bacteria-B, actinomycetes-A, mycorrhizal spores and hyphae-My,
hyphae of a saprophytic fungus-H, a nematode-N, ciliate protozoa-CP, flagellate protozoa-FP, and a mite-M .) This
soil can be a habitat of enormous complexity and diversity even over small distances . For example, the actual size
of the soil in this drawing is < 1 mm in both directions yet may contain habitats that are acid to basic, wet to dry,
aerobic to anaerobic, reduced to oxidized, and nutrient-poor to nutrient-rich . Realizing this complexity and diversity
rho kpv tr tindarstandina soil microbiology . Original drawing by Kim Luoma . Used with permission .
A depiction of representative groups of soil microorganisms, showing their relative sizes . (Drawing courtesy of R . Weil)
FIGURE 10 .8
Diagram of ectomycorrhiza and arbuscular mycorrhiza (AM) association with plant roots . (a) The ectomycorrhiza association produces short branched rootlets that are covered with a fungal mantle, the hyphae of which extend out into the soil and
between the plant cells but do not penetrate the cells . (b) In contrast, the AM fungi penetrate not only between cells but into certain
cells as well . Within these cells, the fungi form structures known as arbuscules and vesicles . The former transfer nutrients to the plant,
and the latter store these nutrients . In both types of association, the host plant provides sugars and other food for the fungi and receives
in return essential mineral nutrients that the fungi absorb from the soil . [Redrawn from Menge (1981) ; Photo courtesy of R . Weil]
FIGURE 10 .16