MIKROORGANISME

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MIKROORGANISME BAHAN ORGANIK TANAH
AGROTEKNOLOGI
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(No Transcript)
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In 1 teaspoon of soil there are
Bacteria 100 million to 1 billion
Fungi 6-9 ft fungal strands put end to end
Protozoa Several thousand flagellates amoeba One to several hundred ciliates
Nematodes 10 to 20 bacterial feeders and a few fungal feeders
Arthropods Up to 100
Earthworms 5 or more
Travis Gugino - PSU
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Soil Organisms

• Significance/Fungsinya
• 1. Decomposition of plant and animal residues
• 2. Release of nutrients and inorganic elements
  which feed plants and cause mineral weathering
• 3. Synthesis of new organic compounds
• 4. Humus formation to increase cation exchange
  and structure
• 5. Nitrogen fixation

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Soil Organisms Cont.

• Kind
• 1. Plant
• 2. Animal
• Plants ( bacteria, actinomycetes, fungi, algae)
• 1. Bacteria
• 1. Very small single celled organisms
• 2. Multiply by elongation and dividing into 2
  parts
• 3. Millions or even billions per gram of soil

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I. Classification of Bacteria (Heterotropic)

• A. Heterotropic obtain their carbon and energy
  from various organic compounds
• 1. Nitrogen fixing derive their nitrogen in
  gaseous form from the atmosphere or they can
  obtain their nitrogen from Ammonia or Nitrates
• a. Non Symbiotic - those that are free living
• 1. Anaerobic organisms - those not needing
  free oxygen for respiration

Dont need Host Plant
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• Clostridium
• More common in forest soils
• Optimum Reaction pH 6.9 - 7.3
• no fixation below pH 5.0
• 2. Aerobic- need free oxygen
• Azotobacter
• More common in agriculture soils
• Very sensitive to acidity
• pH below 5.5 to 6.0 no fixation

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b. Symbiotic - live on host plant to mutual
advantage Rhizobium - Find on nudules -
Nitrogen from the air c. Aerobic Bacteria-
requiring combined Nitrogen Bacillus
mycoides - Cause denitrification d.
Anaerobic Bacteria - which require combined
Nitrogen - Nitrates ---------- Nitrites,
ammonia - Sulfates ---------- Sulfites,
sulfides
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Classification of Bacteria (Autotrophic)

• B. Autotrophic- derive their carbon primarily
• from CO2 of the atmosphere and their
• energy from the oxidation of inorganic
• compound or simple compounds of
• carbon

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Cont.

• 1. Bacteria using nitrogen compounds as an
  energy source
• a. Nitrosomes
• - oxidize ammonium Nitrite
• - NH4 NO2-

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Cont.

• b. Nitrobacter
• - Oxidize Nitrite to Nitrate
• - NO2- NO3-
• - little or no activity below a pH of 6.0
• - little or no activity below a temp of 65oF
• 2. Bacteria using sulfur or sulfur compounds as
  energy sources.
• a. Thiobacillus
• S O2 H2O H2SO4

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SOIL MICROORGANISM
Bacteria
UBC EM facility
Pseudomonas
Arthrobacter
CIMC
Bacillus
Travis Gugino - PSU
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II. Actinomycetes

• Unicellular micro-organisms
• Transitional between the bacteria and fungi
• Effect of soil pH
• a. Sensitive to acid soil- no activity below pH
  5.0, optimum activity between 6.0 - 7.5
• Heterotropic Feeders- breaks down organic matter
  and humus liberating nutrients, especially
  nitrogen
• form NH3

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Actinomycetes
Paul R. August
Streptomyces
Travis Gugino - PSU
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Nitrogen Cycle
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III. Fungi

• Heterotropic organisms
• Fungi will tolerate a wide pH range
• abundant in acid soils where bacteria and
  actinomycetes offer only limited competition
• Activities of Fungi
• Decompose organic residues

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Fungi Cont.

• Micorrhiza- fungus roots
• more common in forest soils
• fungal roots form a mat around the absorbing root
  while others penetrate the root cells
• Symbiotic relationship- help with nutrient
  absorption by increasing absorptive surface
• Pine seedlings will not grow well without them

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Microorganisms
Fungi
Aspergillus
Trichoderma
K.J. Kwon-Chung
PSU Em facility
D.C. Straney
Fusarium
Travis Gugino - PSU
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Mycorrhizae
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IV. Algae

• minute plants which are photosynthetic
• found in surface soils but in low amounts
• Blue green types are important in wet soil
• fix nitrogen in rice paddies
• give off oxygen to the water

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Soil Macro Animals

• Include- rodents, insects, millipedes,
  centipedes, earthworms
• Earthworm- most important macro animals
• may pass as much as 15 tons of dry earth per acre
  through their bodies
• Micro-organisms and the nitrogen cycle
• Organic matter of mineral soils
• Source- remains of plants and animals

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Nematodes
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Many beneficial effects from activities of
microorganisms

• Microorganisms produce
• Plant growth hormones
• Stimulate plant growth hormones
• Compete with disease organisms

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• SOIL ORGANIC MATTER
• (BAHAN ORGANIK TANAH)

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Soil ComponentsThe 4 parts of soil
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Soil Organic Matter

• SOM consists of a broad spectrum of chemical
  classes, including amino acids, lignin,
  polysaccharides, proteins, cutins, chitins,
  melanins, suberins, and paraffinic
  macromolecules, as well as organic chemicals
  produced by humans.

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SOIL ORGANIC MATTER

• Soil Organic matter
  encompasses all organic components of a soil
• Fresh residues
• Decomposing organic matter
• Stable organic matter
• Living organisms

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• Composition
• of green tissue 75 is water
• of dry matter in mature plants
• Sugars and starches 1-5
• Carbohydrates Hemicellulose 10-28
• Cellulose 20-50
• Fats, waxes, tannins, etc 1-8
• Lignin's 10-30
• Proteins Simples water soluble 1-15
• and crude protein

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Changes of Organic Compounds in the Soil

• I. Compounds Characteristic of Fresh Plant
  Tissue
• Decompose with difficulty Decompose easily
• Lignin Cellulose
• Fats Starches
• Oils Sugars
• Resin Proteins

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• II. Complex Intermediate Products of Decay
• Resistant compounds Decomposition compounds
• Resigns Amino acids
• Waxes Amides
• Oils and Fats Alcohols
• Lignin Aldehydes

III. Products of Soil-Decomposition
Processes Resistant complex Simple end
products Humus- a colloidal complex carbon
dioxide and water nitrates,
sulfates phosphates, calcium
compounds
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Rate of Decomposition

• - Burning process - oxidation
• 1. Sugars - Starches - simple proteins Rapid
• 2. Crude proteins
• 3. Hemicellulose
• 4. Cellulose
• 5. Lignins, fats, waxes Very Slow

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The Carbon Cycle
- cycle of life energy cycle
CO2
Animal
To Atm.
Farm Manure
Green Manure Crop Residue
Soil Reactions
CO3 , HCO3
Microbial Activity
Carbon Dioxide
Drainage losses CO2 Carbonates
Bicarbonates of Ca, Mg, K, Etc.
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Humus

• Humus is a mixture of complex compounds and is
  not a single material. These compounds are
  either (a) resistant materials (b) compounds
  synthesized within microbial tissue.
• Definition- Humus is a complex and rather
  resistant mixture of brown or dark brown
  amorphous and colloidal substances that have been
  modified from the original tissue or have been
  synthesized by various soil organisms

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Humus Properties

• 1. highly colloidal
• 2. amorphous (not crystalline)
• 3. cation exchange Cap. 150-300 me/100 gms.
• Clay 8-100 me/100 gms.
• 4. absorption of water from sat. atmosphere
  80-90 clay 15-20

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Carbon Nitrogen Ratio

• Carbon Nitrogen ratio fairly constant in soils
• in cultivated soils 10 or 121 is a common ratio
• in plant material Legumes 201
• Straw 901
• Sawdust 1501
• Thus it can be seen that organic matter contains
  large amounts of carbon and comparatively small
  amounts of nitrogen.

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Influence of Soil Organic Matter on Soil
Properties

• 1. Soil Color - brown to black
• 2. Influence on physical properties
• - granulation encouraged
• - plasticity cohesion reduced
• - H2O holding capacity increased

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• 3. High cation adsorption
• - 2 x 20 x clay
• - 30 - 90 adsorbing power of mineral
• soils
• 4. Supply and availability of nutrients
• - N, P and S held in organic forms
• - Manure (10 - 5 - 10)/ ton (5 - 1 - 5)
  N P K Available

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QUANTITY IN SOILS

• SOM in mineral soil up to 18 by weight
• Typically 0.5 to 5.
• SOM gt 18 in organic soils
• SOM about 50 C
• SOM (OC)(factor) where the factor 1.8 to 2.0
• For most estimations 2 is a good round number
• Older books use a factor 1.724

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How is SOM Measured?

• SOM is usually measured in the laboratory as
  organic carbon,
• Soil organic matter is estimated to contain 58
  organic carbon (varies from 40 to 58) with the
  rest of the SOM comprising of other elements (eg,
  5 N, 0.5 P and 0.5 S).
• A conversion to SOM from a given organic carbon
  analysis requires that the organic carbon content
  be multiplied by a factor of 1.72 (1.00/0.58).
• Thus, 2 SOM is about 1.2 organic carbon.

Testing for Soil Organic Carbon
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Walkley Black

• Oxidize SOM to CO2 using acid dichromate
• Assume C is in the zero oxidation state as in
  carbohydrates (CH2O).
• 3CH2O 16H 2Cr2(VI)O72- --gt 4Cr3 3CO2
  11H2O
• Titrate excess Cr2(VI)O72- with Fe2
• Not used much any more

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Components of SOM
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KESIMPULAN

• Roles of Soil organisms Decomposition of plant
  and animal residues, Release of nutrients and
  inorganic elements, synthesis of new organic
  compounds, Humus formation, Nitrogen fixation
• Soil organic matter all living organisms
  (microorganisms, earthworms, etc), fresh residues
  (old plant roots, crop residues, recently added
  manures), decomposing organic matter and stable
  organic matter (humus).
• Influence of Soil Organic Matter on Soil
  Properties Soil Color - brown to black,
  Influence on physical properties (granulation ,
  plasticity , H2O holding capacity ), High
  cation adsorption, Supply and availability of
  nutrients.
• SOM is usually measured in the laboratory as
  organic carbon, A conversion to SOM from a given
  organic carbon analysis requires that the organic
  carbon content be multiplied by a factor of 1.72
  (1.00/0.58).