Soil Organic Matter

Soil Organic Matter - SOIL
ORGANIC
MATTER
 SOM
...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: SOIL
ORGANIC
MATTER
 SOM
 Peat
–
Isle
of
Lewis,
Scotland
 SOM
 •  Especially
in
“O’
and
“A”
 –  Nutrients
 •  Important
for
 –  Support
micro
and
 macro
organisms
 –  CEC
 •  They
are
part
of
SOM
 –  Holding
water
 –  Tilth….
 –  FormaGon
of
peds
‐
 structure
 –  Most
of
this
next
week
 Carbon
cycle
 •  We
will
cover
this
next
 week
in
detail
 •  Greenhouse
effect
 •  Global
warming
 •  Carbon
sink
 –  Soils
have
the
highest
%
 of
C

 Carbon Cycle CO2 O2 CO2 CO2 Litter Organic Horizons Soil Reactions Crop Residues Animal Manure CO3, HCO3 Microbial Activity Microbial Activity tion liza inera Carbon Dioxide M Leaching Losses Interconnected
to
other
cycles
 •  Especially

 •  Oxygen

O
 •  Sulfur

S
 •  Hydrogen
H
 •  Nitrogen
N
 •  Potassium

K
 •  Phosphorous

P
 This diagram illustrates how connected life on Earth is. SOM •  Soil Organic matter encompasses all organic components of a soil: –  Fresh residues –  Decomposing organic matter •  ACTIVE –  Stable organic matter •  humus –  Living organisms Fresh Residues •  Up to 15% of organic is fresh residue •  Comprised mainly of litter fall •  Much can be recognized as plant residue matter Decomposing Organic Matter •  Plant material is transformed from one organic compound to another mainly by organisms in the soil •  Organisms create –  by-products, wastes, and cell tissue •  Compounds released as waste by one organisms can often be used as food by another –  recycle STABLE ORGANIC MATTER HUMUS •  Newly-formed humus: combination of •  a) resistant materials from the original plant tissue, and •  b) compounds synthesized as part of the microorganisms' tissue which remain as the organisms die. (Fluvic and Humic Acid) •  humus is resistant to further microbial attack-
 Leaf Humus Living Organisms – Soil Ecosystem Soil ecosystem Insects Birds Animals Fungi Animals Organic Matter: waste, residue, and metabolites of plants, animals, and microorganisms Worms Bacteria LIFE
 •  Many
soils
are
teeming
 with
life,
especially
in
 the
O
and
A
horizons.
 •  Microbes,
plants
and
 animals
live
in
the
soil;
 •  
some
of
each
are
 •  Soil
ecology
is
the
study
 beneficial
while
others
 of
interrelaGonships
of
 are
harmful
to
higher
 soil
organisms.
 plants
and
animals.
 •  Animals
present
depend
 on
the
 –  Climate
 –  VegetaGon
 –  Soil
type
 Fauna
‐
flora
 KINGDOMS
OF
LIFE

 ‐
6
KINGDOMS
 Prokaryotes
 •  An
organism
whose
cells
contain
no
nucleus
or
 certain
other
internal
structures
characterisGc
 of
the
cells
of
higher
organisms.
 Eukaryotes
 •  An
organism
whose
cells
are
characterized
by
 a
nucleus
with
chromosomes,
mitochondria,
 and
other
complex
internal
structures.
 Eukaryote
 1)
ARCHAEOBACTERIA
 •  Prokaryote
‐
unicellular
‐
old
bacteria
 •  single
celled
 •  extreme
living
condiGons
 1)
ARCHAEOBACTERIA
 extremophiles
 2)
EUBACTERIA
 •  Prokaryote
‐
unicellular
‐
true
bacteria
 •  Cyanobacteria
 –  prokaryoGc
organisms
without
organized
chloroplasts
but
having
 chlorophyll
a
and
oxygen‐evolving
photosynthesis;
sGll
commonly
 called
blue‐green
algae.
 –  NOT
ALGAE
 –  aquaGc,
eucaryoGc
one‐celled
or
mulGcellular
plants
 •  over
3
billion
years
old
 2)
EUBACTERIA
 Greek,
eu
=
true]
The
 commonly
occurring
 prokaryotes
that
live
in
 water
or
soil,
or
within
 larger
organisms;

 Archaebacteria
and
 Eubacteria
differ
from
 each
other
in
their
 metabolic
abiliGes,
the
 composiGon
of
their
 membranes,
and
the
 structure
of
their
 ribosomes.
 3)
PROTISTA
 •  Eukaryote
‐
unicellular
and
mulGcellular
‐
simple
 organisms.
 •  •  •  •  •  •  protozoans
‐
amoeba
‐
ciliates
‐
flagellates
 dinoflagellates
 diatoms
 nanoplankton
 foraminifera
(Forams)
 radiolarian
 protozoans
‐
amoeba
‐
ciliates
‐
 flagellates
 dinoflagellates
 diatoms
 Nanoplankton
 foraminifera
(Forams)
 radiolarian
 4)
FUNGI
 •  Eukaryote
‐
unicellular
and
mulGcellular
‐
 simple
organisms
‐
consumers.
 •  mushrooms
 •  yeast
 Fungi
 mycellium
 5)
PLANTS
 •  Eukaryote
‐
mulGcellular
‐
photosynthesize
‐
 producers
mainly
 6)
ANIMALS
 •  ‐
Eukaryote
‐
mulGcellular
‐
consumers.
 Macrofauna
‐
microfauna
 Macrofauna
‐
microfauna
 diversity
 diversity
 •  Grasslands
have
higher
 #’s
of
animals
but
less
 diversity
than
forests
 Red
–
high
diversity
 Producers
‐
consumers
 Autotrophs
 •  are
producers;
 •  
they
make
organic
 compounds
from
 inorganic
C,
mostly
from
 CO2
 •  An
autotroph,
or
 producer,
is
an
organism
 that
produces
complex
 organic
compounds
(such
 as
carbohydrates,
fats
and
 proteins)
from
simple
 inorganic
molecules
using
 energy
from
light
(by
 photosynthesis)

 •  OR
inorganic
chemical
 reacGons
 (chemosynthesis).

 PRIMARY
PRODUCERS

 •  PLANTS
are
the
main
 PRIMARY
PRODUCERS

 –  of
organic,
C‐based
 molecules
 •  photosynthesize
 Photosynthesis Light CO2 H 2O 6 CO2 + 12 H2O + Light O2 C6H12O6 (sugar) H 2O C6H12O6 + 6 O2 + 6 H 2O Through the process of photosynthesis, plants absorb CO2 from the atmosphere, transform it into plant carbon, and sequester it in either above- or below-ground biomass and/or soil carbon. Photoautotrophs
 •  such
as
higher
plants
 and
most
algae,
obtain
 their
energy
from
light.
 Chemoautotrophs
 •  such
as
nitrifying
and
S‐ oxidizing
bacteria,
 obtain
energy
from
 minerals.
 Heterotrophs
 •  are
consumers
and
 decomposers,

 •  using
the
organic
 compounds
made
by
 autotrophs.
 Chemoheterotrophs
 •  including
humans
and
 fungi,

 •  eat
or
decompose
 previously
made
organic
 compounds
for
energy;
 •  they
can't
make
their
 own
organic
 compounds.
 Consumers
&
decomposers
 •  This
material
is
then
 altered
by
 •  HERBIVORES
‐
eat
live
 plants
 •  CONSUMERS
and
 DECOMPOSERS
of
C.
 •  but
most
are
 DETRITIVORES
‐
eat
the
 dead
material
(plants
 and
animals)
‐
detritus
 Producers
‐
Consumers
 PRIMARY
CONSUMERS

 •  typically
animals
that
 feed
on
the
plant
 majer
–
alive
OR
dead
 and
decaying
plant
 majer
 •  Use
energy
stored
in
 plant
residue
 HERBIVORE
 •  typically
animals
that
 •  Use
energy
stored
in
 feed
on
alive
plant
 plant
residue
 majer
 •  nematodes,
insect
 •  PROBLEM
–
as
we
may
 larvae,
termites,
ants
 want
that
material…
 •  physically
ajack
the
 plant
majer
by
chewing
 and
tearing
Gssue
and
 moving
the
material
 DETRITIVORE
 •  typically
animals
that
 feed
on
dead
plant
 majer
 •  Most
soil
organisms
   Especially
fungi
and
 bacteria
 •  Use
energy
stored
in
 plant
residue
 •  Residue
broken
down
to
 simple
sugars.
 Consumers
 •  living
and
dead
add
to
 the
soil
 •  as
they
use
the
C
they
 also
decompose
it
 •  Energy
is
eventually
 released
by
consumers
 as
heat,
and
C
is
 returned
to
the
 atmosphere
as
CO2
 during
respiraGon.
 Consumers
 •  ProGsts,
fungi,
and
 bacteria
can
also
be
 primary
consumers,
 oken
chemically
 degrading
Gssues
 SECONDARY
CONSUMERS

 •  Predators
that
eat
the
 primary
consumers
 •  Carnivores
 –  CenGpedes.
Mites.
 Spiders.

Nematodes,
 snails
 –  ‐
humans…
 •  MicrophyGc
feeders
if
 they
eat
microflora

 •  e.g.
eat
colonies
of
 fungi
and
bacteria.
 Producers
‐
consumers
 TERTIARY
CONSUMERS

 •  eat
secondary
 consumers
 •  E.g.
ants
eat
spiders
and
 mites.

Birds…
 •  And
so
on
up
the
food
 chain.
 Producers
‐
consumers
 DECOMPOSERS
 •  release
C
as
CO2
 •  UlGmate
decomposers
 are
the
soil
microbes,
 including
bacteria,
fungi
 and
acGnomycetes,
which
 break
down
detritus
and
 primary,
secondary
and
 terGary
consumers.
 •  They
are
responsible
for
 recycling
nutrients.
 •  BUT
‐

consumers
are
 decomposers
and
 decomposers
are
 consumers

 •  We
define
the
 microorganisms
as
 decomposers
IF
they
 are
most
closely
related
 to
the
ulGmate
release
 of
the
nutrients
 Final
detriGvores…
 •  They
excrete
enzymes
 •  minerals
released
and
 e.g
PROTEASE
for
 added
back
to
the
soil
 proteins;
CELLULASE
for
 (again)
‐
in
inorganic
 cellulose
which
react
 form
called
 with
the
organic
 MINERALIZATION
 material
to
form
 –  Heat
 –  CO2
(
returned
to
the
 atmosphere)
 •  CYCLING
OF
C
 atmosphere‐plants‐ consumers‐ decomposers
–
 atmosphere
 •  without
it
there
would
 be
no
CO2
in
the
 atmosphere.
 ANIMALS

 •  Microanimals
 •  Microfauna
 •  less
than
0.2
mm

 •  are
microscopic.
 1)

NEMATODES
 •  microscopic
worms
‐
 most
abundant
soil
 animal
 •  thread
‐
like,
small

‐
 thinner
than
a
cojon
 thread
‐
unsegmented.
 •  feed
on
dead
o.m.,
 other
micro‐animals,
or
 are
plant
parasites.
 •  Can
enhance
or
destroy
 acGvity
of
fungi
or
 bacteria
 •  some
grazing
sGmulates
 growth
‐
overgrazing
 kills
colonies
 •  BUT
‐
A
problem
for
 crops
 •  nematodes
may
live
in
 soil
and
feed
on
roots
 (ectoparasites)

 •  or
live
inside
plants
 (endoparasites).

 •  

 •  ParasiGc
nematodes
can
 cause
galls
or
stunGng,
 and
transmit
diseases.
 •  e.g.
carrot
worm,


 pineapple
in
hawaii
 •  SOLUTION

 •  
grow
a
non
host
crop
 •  
OR
plant
marigolds
or
 canola
(rapeseed)
 Beneficial‐
to
whom??
 •  Spray
contains
 beneficial
nematodes
 onto
a
tree
wound
to
 control
lesser
peachtree
 borer.

 •  

 2)
PROTISTA
 •  Protozoa
are
one‐celled

 •  form
a
numerous
and
 diverse
group
of
soil
 microbes;
over
250
 species
have
been
 found.
 ProGsta
 •  They
live
in
the
water
 around
soil
parGcles,
 eaGng
bacteria
and
 occasionally
some
fungi,
 algae
or
o.m.,
which
 may
hasten
the
 turnover
of
readily
 available
nutrients.
 •  Larger
and
more
 structure
to
the
cells
 than
bacteria
 3)
ALGAE
 •  EukaryoGc
cells
‐
nuclei
 and
membrane
 •  They
are
usually
 photosyntheGc
so
live
 near
the
surface.

 •  Like
it
moist
 •  Can
turn
a
soil
green
or
 orange
in
sufficient
 numbers.
 •  usually
1‐10
billion
per
 m3
 fungi
 4)
BACTERIA

 •  simple
single
celled,
very
 small,
‐
most
are
less
than
 1/25,000"
in
diameter.
 •  Present
in
immense
 populaGons
(up
to
2
 quinGllion
[2
x
1018]
in
2/3
 acre),
though
their
 numbers
fluctuate
widely
 with
different
 environmental
condiGons.
 Bacteria
 •  binary
fission
for
 reproducGon
‐
 someGmes
as
oken
as
 every
20
minutes
 •  can
reproduce
very
fast
 in
favorable
condiGons

 Some
problems
 •  BUT
puts
tremendous
 strain
on
the
nutrients
 available,
and
waste
 products
accumulate
and
 become
toxic.
 •  Bacillus
cereus
is
a
 bacteria
commonly
found
 in
soil.
 Bacteria
 •  Many
are
beneficial
but
 •  C.
perfringens
is
one
of
 many
are
harmful
to
 the
most
common
 plants.
 bacterium
responsible
 for
food‐borne
illnesses.
 •  Anaerobic
bacteria
 need
a
saturated
soil,
 while
aerobic
bacteria
 need
the
O2
of
a
well‐ drained
soil
 Bacteria
 •  Most
bacteria
prefer
 the
same
moisture
 levels
as
plants.
 •  Most
beneficial
 Bacteria
 •  Bacteria
usually
like
high
 Ca,
pH
6‐8
 •  70‐100oF
(so
killed
by
 sterilizaGon).

 •  But
there
are
excepGons
 to
each
‐
some
prefer
very
 low
or
high
pH,
or
 extreme
cold
or
some
 heat.
 FixaGon
 ‐
make
available
to
plants

 •  Autotrophic
bacteria
 obtain
energy
by
 oxidizing
minerals
such
 as
N,
S
and
Fe,
and
get
 their
C
from
CO2.These
 are
very
important,
as
 they
are
responsible
for
 nitrificaGon,
S
oxidaGon
 and
N
fixaGon.
 •  Heterotrophic
bacteria
 obtain
both
energy
and
 C
from
o.m.


 •  These
decay
plant
 material
and
cause
 ammonificaGon.
 •  N‐fixing
bacteria
live
 free
in
soil
or
in
root
 nodules.

The
bacteria
 obtain
CHO
from
their
 hosts'
roots;
in
return,
 they
give
some
of
their
 N
to
the
host
 •  These
bacteria
are
host‐ specific,
so
if
you
decide
 to
inoculate
your
 legumes
with
them,
be
 sure
to
use
the
right
 kind.
 •  Many
bacteria
are
 harmful
to
plants,
being
 especially
bad
in
wet
 years;

 •  they
dry
out
easily
and
 travel
in
water,

 •  plants
remain
sok
so
 easier
to
ajack
longer.
 •  Bacteria
that
 decompose
o.m.
 compete
with
crops
for
 N
when
fresh
o.m.
is
 added
to
a
soil.
 •  Blue‐green
"algae"
are
 proGsts,
not
true
algae.
 5)
ACTINOMYCETES
 •  Soil
acGnomycetes
=
ray
 fungi
=
thread
bacteria
 resemble
both
fungi
 and
bacteria.
 •  Like
fungi,
they
have
a
 profusely
branched
 mycelium,
but
with
 thinner
filaments.

Have
 fruiGng
bodies
too.
 •  Like
bacteria,
they
are
 unicellular,
of
similar
 size,
look
similar
when
 break
up
into
spores.
 •  But
they
tolerate
 drought
bejer
than
 bacteria
or
fungi.
 •  They
are
most
 abundant
in
moist,
well‐ aerated
soils.
 AcGnomycetes
 •  They
are
inacGve
below
 •  Large
acGnomycete pH
5.0,
so
diseases
they
 populaGons
are
found
 cause
can
be
controlled
 in
soils
that
have
been
 by
lowering
the
soil
pH.
 under
sod
a
long
Gme;
 only
bacteria
are
 •  Some
acGnomycetes
 present
in
larger
 are
important
 numbers.
 decomposers.
 6)
FUNGI
 •  Fungi
are
 nonchlorophyllous,‐
 eukaryoGc
cells
without
 photosynthesis‐
non‐ vascular
plant‐like
 organisms.
 •  over
700
species
‐
 includes
molds
and
 mushrooms
 •  can
be
primary,
 secondary
or
terGary
 consumers
 •  Many
fungi
are
 important
 decomposers,

the
most
 versaGle
decomposers
 of
o.m.;

 •  they
can
decay
even
the
 most
resistant
 compounds
such
as
 lignin,
 •  they
are
the
best
humus
 formers.
 •  1)
yeasts
–

 eukaryoGc
micro‐organisms
 classified
in
the
kingdom
 Fungi,
 anaerobic
soils
 •  2)
molds

 Molds
(or
moulds)
are
fungi
 that
grow
in
the
form
of
 mulGcellular
filaments
 called
hyphae.
 •  Many
types
are
most
 prolific
in
acid
soils
 because
bacteria
don't
 compete
well
in
acid
 soils.


 •  At
pHs
favored
by
most
 horGcultural
crops,
 bacteria
compete
more
 successfully
than
fungi.
 •  3)
mushrooms
‐
not
 truly
microscopic
 mushrooms
have
a
web
 of
MYCELLIUM
below
 the
ground
and
the
 mushroom
‐
spore
 producer

‐
above
the
 ground
the
mycellium
 are
someGmes
visible
 Mycorrhizae
 •  are
fungi
that
live
in
 close
associaWon
with
 roots.
 Mycorrhizae
 •  a)

They
help
plants
 obtain
nutrients,
 especially
P,
Zn,
and
Cu,
 so
are
very
important
in
 inferGle
soils
‐
they
are
 very
common
on
many
 forest
trees
and
on
 orchids.
 •  b)
Mycorrhizae
also
 help
plants
tolerate
 drought.
 Mycorrhizae
 •  c)
In
return,
the
host
 plant
gives
the
fungus
 CHO.
 •  d)
Mycorrhizae
are
also
 common
on
vegetable
 and
agronomic
crops.
 •  e)
Ectotrophic
 mycorrhizae
form
a
 mantle
around
roots,
 common
trees
(especially
 oak,
pine).
 •  f)

Endotrophic
 mycorrhizae
=
vesicular‐ arbuscular
(V‐A)
 mycorrhizae,
are
more
 common
on
field
crops,
 invading
roots,
and
on
 many
trees
(maple).


 •  g)
Mycorrhizae
are
 harmed
when
soils
get
 too
hot,
such
as
when
 surrounding
trees
are
 cleared
to
widen
a
road,
 thereby
exposing
the
 soil
to
sun.
 •  h)
Chemical
ferGlizers
 may
also
kill
 mycorrhizae.
 •  just
before
we
start
 with
the
 macroorganisms

 •  I
want
to
add
one
extra
 fact
about
the
micro
 •  FUNGI
‐
dominant
‐
 good
soil
 •  bacteria
dominant
‐
 usually
anaerobic
 condiGons
‐
waterlogged
‐
 putrefacGon
‐
toxins
‐
 methane,
formaldehyde,
 Hydrogen
sulfide
etc
 harmful
to
soil
animals
 and
retard
plant
growth
 they
are
slightly
bigger
 than
bacteria.
 •  But
fungi
cause
far
 more
plant
diseases
 than
any
other
 organism.

Soil
fungi
are
 oken
responsible
for
 root
rots,
lower
stem
 rots
and
seedling
 damping‐off.
 7)
PLANTSmicro
and
macro…
 •  Plants
must
be
 considered
as
soil
 organisms.
 •  Their
roots
and
other
 underground
organs
are
 in
constant
contact
with
 the
soil.
 •  They
help
break
parent
 rock
to
form
soil.
 •  They
granulate
soil
with
 their
exudaGons
and
 fine
roots.
 •  They
reduce
erosion.
 •  They
extract
water
and
 nutrients.
 •  They
put
nutrients
back
 and
contribute
to
o.m.
 when
they
die.
 •  They
serve
as
food
for
 other
soil
organisms.
 •  So,
there
are
usually
10
 Gmes
as
many
 organisms
in
the
 rhizosphere
as
in
the
 rest
of
a
given
soil.
 Macroanimals
 •  can
be
seen
with
the
 naked
eye.
 •  Very
large
soil
animals
 include
earthworms,
 gophers,
moles,
shrews,
 mice
and
prairie
dogs
 mix
soil
as
they
move
 around
and
dig
burrows
 •  Macroanimals
are
helpful
 in
turning
and
granulaGng
 the
soil,
mixing
in
o.m.,
 adding
their
feces,
and
 eaGng
bad
soil
animals.

 But
also
create
big
air
 pockets
around
roots,
eat
 roots
and
girdle
lower
 stems,
someGmes
eat
 large
parts
of
herbaceous
 plants,
and
create
ugly
 tunnels
through
lawns.
 1)

EARTHWORMS
 •  the
best
known
soil
 animal
and
are
 probably
the
most
 beneficial
soil
animals

 •  
only
a
few
‐ve’s
worms
 are
hermaphrodites
 •  eat
dead
plant
material
 and
microorganisms
 from
the
surface,
or
 within
the
soil
 •  they
make
their
way
 through
the
soil
by
 ingesGng
it

(2‐30x
their
 own
weight/day)
‐

and
 excrete
much
material.
 •  1)
mix
up
the
soil
 material
in
their
 digesGve
tract
‐
grinding
 lumps
into
smaller
 aggregates

‐
increase
A
 horizon
 •  2)
create
ferGle
casGngs

 •  produces
its
weight
/
 day
‐
on
surface
or
in
 soil
 •  higher
in
beneficial
 bacteria,
o.m.,
pH,
CEC,
 %
base
saturaGon,
N,
 available
P
and
K,
and
 exchangeable
Ca
and
 Mg
than
surrounding
 soil.
 •  3)

create
channels
 aiding
water
infiltraGon,
 root
penetraGon
and
 aeraGon
 •  4)

they
mix
and
 granulate
soils
by
taking
 o.m.
down
and
lower
 soil
upward.
 •  5)

they
improve
the
 size
and
stability
of
soil
 aggregates
‐
worm
 casGngs
are
stable.
 •  6)

Turf
grass
‐
+ve
‐
 reduces
compacGon
 and
thatch
formaGon‐ve
 ‐
casGngs
on
the
surface
 •  WORMS

‐
Favor
moist
 but
well
aerated
soils
 with
fresh

o.m.
for
 food
,
slightly
acid,
 some
Ca,
and
about
 50oF.
 •  most
acGve
in
Spring
 and
Fall
 •  acid
forest
soils
‐
1
 worm
/
meter3;

 grasslands
‐
30‐300
m3
 •  they
die
quickly
when
 exposed
to
ultraviolet
 light
so
they
eat
at
the
 surface
at
night
 •  they
can
drown
in
a
 heavy
rain
so
they
come
 to
the
surface
 •  dislike
sand
as
abrasive
 •  symbioGc
relaGonship
 with
bacteria
‐
they
 digest
material
that
 becomes
accessible
 then
to
bacteria
‐
the
 bacteria
digest
material
 for
worms
‐
and
the
 worms
eat
the
bacteria
 ‐
60%
protein
0%
fat!
 
ARTHROPODS
 •  exsoskeleton
and
jointed
 legs
‐
insects
‐
very
 successful
for
600
million
 years
 •  springtails
and
mites
‐
live
 in
macropore
spaces
‐
 move
and
breakdown
 materials
 •  Springtails
‐
feed
on
dead
 plants,
animal
Gssue,
 feces,
humus
and
fungi
 •  they
do
spring!


1/25
mm
 in
size
‐
abundant
 •  mites
‐
similar
to
 spiders
,
vegetarians
 and
carnivores
‐
can
eat
 harmful
insects
 •  can
be
primary, secondary
or
terGary
 consumers
 •  millipeds
‐
many
legs
‐
 vegetarian
‐
on
dead
 organic
majer
‐
too
 many
is
bad
 •  sow
bugs
–
(woodlouse)
 decompose
o.m
‐
too
 many
is
bad
 •  cenGpedes
‐
less
legs
‐
 carnivores
esp
worms
 ants
and
termites

 •  Both
animals
transport
 soil
material
from
 underground
to
the
 surface
and
can
build
 hills
up
to
1
m.
in
height
 for
ants
and
6
m!
for
 termites
 •  1)

casGngs
not
as
ferGle
 as
worms
as
they
use
 more
of
the
nutrients
 •  2)

can
enrich
A
in
clays
 from
B
(
from
depths
of
 2
m
for
ants
to
3
m
for
 termites)
‐
soil
mixing
‐
 can
completely
 obliterate
the
soil
 horizon
differences
 locally
 •  3)
use
leaves,
rojed
 wood,

roots,
seeds,
 fungi
for
food
–
 consumers
some
grow
 fungi
for
food
 •  4)
create
channels
‐
aids
 irrigaGon
 RODENTS
/
MOLES
 well
‐
what
do
they
do
?
 SLUGS
AND
SNAILS

 •  may
also
feed
on
o.m.
 but
oken
chew
holes
in
 leaves
or
flowers
of
 healthy
plants,
or
eat
 enGre
seedlings.
 •  Others
ajack
plants'
 underground
parts
such
 as
bulbs.
 •  Snails
also
grind
up
 rocks
into
soil.
 5)
GRUBS

 •  e.g
may
fly
‐
round,
 white
2‐3
cm
‐
curls
 when
disturbed
feed
on
 grass
roots
‐
cause
dead
 patches
in
the
lawn
 •  BUT
‐
Many
large,
 ferocious‐looking
 beetles
are
predators
of
 harmful
insects
or
break
 up
large
detritus.
 •  Some
soil
insects,
such
 as
cicadas,
are
neither
 very
beneficial
nor
very
 harmful.
 •  In
summary,
soil
 organisms
work
 together
to
recycle
 carbon
and
minerals.

 There
is
an
enGre
 ecosystem
 underground!
 •  CYCLING
OF
NUTRIENTS
 ‐
exchange
between
the
 soil
and
the
living
parts
 •  plants
and
animals
 absorb
nutrients
‐
 organic
majer
‐
called
 IMMOBILIZATION

 •  plants
are
producers
 •  Microbes
digest
the
 majer
and
release
 nutrients
to
the
soil
–
 MINERALIZATION
 •  microorganisms
are
 decomposers
 •  CYCLING
‐
how
much
of
 this
is
done
 •  case
studies
have
 shown
up
to
86%
is
 recycled.
‐
N,
P,
K,
Ca
 •  we
will
look
at
each
of
 these
nutrients
 individually
over
the
 next
week
and
what
 they
are
needed
for
in
 plant
life.)
 •  really
quite
surprising
 so
much
nutrient
 recycling
 •  the
forests
can
easily
 survive
even
in
fairly
 unferGle
soils
 BUT
WHAT
OF
OUR
CROPPING
SYSTEM
 FOR
FOOD
 •  e,g,
corn
‐
takes
 abundant
nitrogen
from
 the
soil
and
this
is
not
 returned
‐
so
what
do
 we
do
‐
ferGlize
 •  arable
farms
‐
animal
 farms
‐
manure
can
aid
 recycling
 •  BUT
what
is
too
much
 manure
(disposal??)
or
 none
at
all
(ferGlize??)
 ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online