soil biology and organic matter. i.overview a.soil is….. minerals (the body) organisms (the life)...
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Soil Biology and Organic Matter
I. Overview
A. Soil is…..
• Minerals (the body)
• Organisms (the life)
Vital to soil formation and development
I. Overview
A. Soil is…..
• Minerals (the body)
• Organisms (the life)
Vital to soil formation and development
B. Teems with life• 1 million bacterial in each cubic cm of topsoil• 1 million earthworms per acre• More Biomass beneath our feet than above
II. Plants (Macro and Micro)
III. Animals (Macro and Micro)
II. Plants
A.Microflora
Why important?
II. Plants
A.Microflora
Why important?
•Most crucial life forms in soils (by far, the most abundant in number)
II. Plants
A.Microflora
Why important?
•Most crucial life forms in soils•They generate their energy by breaking down complex organic tissue, thereby freeing vital nutrients for other plants.•(Without these critters, these nutrients could be locked up indefinitely in complex organic compounds)
II. Plants
A.Microflora
•Bacteria
Single celled organisms;Greater number of organisms present than all others combined
II. Plants
A.Microflora
•Bacteria
oHeterotrophic – derive energy by consuming complex organic debris (leaves, roots, stems, animal tissue)—releases ammonium for plants
Requiring organic compounds of nitrogen and oxygen for nourishment
Rhizobium Bacteria—fix Nitrogen from air (Legumes)
II. Plants
A.Microflora
•Bacteria
oHeterotrophic – derive energy by consuming complex organic debris (leaves, roots, stems, animal tissue)—releases ammonium for plantsoAutotrophic – oxidize inorganic materials (sulfer, iron, carbon, ammonia).—releases nitrate and nitrite.Producing complex organic nutritive compounds from simple inorganic sources by photosynthesis
A. Microflora
• Actinomycetes (Act-tin-o-my-ce-tes)o Single-celled organisms slightly larger
than bacteria (fine, thread-like)o Decompose complex organic materials
in later stages in conversion to humus.o Capable of producing antibiotics
A. Microflora
• Fungio Heterotrophic organisms capable of
decomposing highly-resistant and complex organic compounds.
o Dominant flora when pH is less than 5
also…mycorrhizae fungus (Mi-cor-rizie)
Extension ofPlant roots
A. Microflora
• AlgaeSimplest green plant (needs sun and water)
Blue-Green Algae most common
Aids in adding organic matter
Old ham sandwich residue from GeologyClub fridge……
A. Microflora
Factors Limiting Microflora
• Adequate supply of organic matter
• Temperature (Peat Bogs too cool, desert too hot)
• Moisture
• pH (6-8 optimal—Rizobium bacteria very sensitive)
• Oxygen Availability (most microflora aerobic)
Whereas microflora are affected by the ambient temperature and moisture, MACROFLORA tend to form in response to climate, parent material, and slope conditions.....
II. Plants
B. Macroflora
•Grasses
•Shrubs
•Trees
Function:
•Produce an array of complex organic materials (leaves, roots, stems, bark, wood, seeds)—affect soil chemistry, water retention, pH, organic matter, etc.
Function:
•Produce an array of complex organic materials (leaves, roots, stems, bark, wood, seeds)—affect soil chemistry, water retention, pH, organic matter, etc.
•Aid in rock weathering and soil formation
•Protect soil from erosion
III. Animals
A.Microfauna
Protozoa (amoebae, ciliates, flagellates)
Single-celled organisms, need moisture (dormant when dry)
“grazers, eat bacteria”—digestion aids organic decomposition.
III. Animals
A.Microfauna
Nematodes (“eel worms”)
•More complex than protozoa
•Dine on decomposing organic matter, living soil animals, living plant roots
•Destructive to crops
III. Animals
A.Macrofauna
Ants and Earthworms
Major mixers of soil
Openings allow air and water movement
III. Animals
A.Macrofauna
Springtails, Mites, Mammals, Humans
“mix, mechanically alteradd organics…”
IV. Soil Organic Matter
A.Sources
IV. Soil Organic Matter
A.Sources
•Predominantly from plant tissue
•Animals (minor source)
•Earthworms, centipedes, ants process and move plant residues
IV. Soil Organic Matter
B. Humus Formation1. Term used for organic matter which has gone under extreme decomposition
Raw OrganicMatter Humus
Extensive decomposition
Great source of N, P, S
IV. Soil Organic Matter
B. Humus Formation
2. The ingredients of humus…
(N Compound)
(Humus)
Proteins—stores and slowly releases N in soilAlso find concentrations of P, S, and high CECAbility to absorb large volumes of water
IV. Soil Organic Matter
B. Humus Formation3. Carbon/Nitrogen relationships
Raw OrganicMatter Humus
Extensive decomposition
800 Carbons1 Nitrogen
10 Carbons1 Nitrogen
Why not use sawdust or raw vegetation?
Why not use sawdust or raw vegetation?•Raw vegetation invites large microbial population (they feed on C).•Compete for N, and make it less available to higher plant communities.
Why not use sawdust or raw vegetation?•Raw vegetation invites large microbial population.•Compete for N, and make it less available to higher plant communities.
•Decomposition of organics (CO2 gas), and many critters die and decompose. Nitrogen remains.•N fixed as protein in the microbes is now available to plants•Resultant humus is highly enriched in N relative to the original raw vegetation, and has a greater surface area (higher CEC)
So…should we add sawdust to a garden?
C:N = 400/1
C:N = 10/1
4. Carbon Cycle
IV. Soil Organic Matter
C. Amount and Distribution
C. Amount and Distribution
1. Influence of Climate and Vegetation
Metric tons of organic matter per ha of 1 meter depth
Wisconsin study of prairie vs. forestsoils.
Practical Implications•Clear and burn method of woodlands removes the majority of organics•Cropping grasslands reincorporates organic matter into the system
IV. Soil Organic Matter
C.Composting
1. (Compost)—organic material that has undergone significant biological decomposition
IV. Soil Organic Matter
C.Composting
1.(Compost)—organic material that has undergone significant biological decomposition
2.Benefits:
•Reduces volume of organic wastes by 5-10x.
•Heat generated during decomposition kills many disease-causing microbes
•Lowers C:N
•Serves as excellent soil conditioner
V. Soil Fertility
A.Fertilizers
V. Soil Fertility
A.Fertilizers
A. Fertilizers 5 – 10 – 5N P K
V. Soil FertilityA. FertilizersNitrogen
Sources: ammonium, nitrate
V. Soil FertilityA. FertilizersNitrogen
* darker, stronger leaves
V. Soil FertilityA. FertilizersNitrogen
* darker, stronger leaves* helps with uptake of other
nutrients
V. Soil FertilityA. FertilizersPhosphorous
Sources: ??
V. Soil FertilityA. FertilizersPhosphorous
* strengthens stems and roots
V. Soil FertilityA. FertilizersPhosphorous
* strengthens stems and roots* enhances flowering, and seed
production
V. Soil FertilityA. FertilizersPhosphorous
* strengthens stems and roots* enhances flowering, and seed
production* increases plant’s resistance to
certain diseases
V. Soil FertilityA. FertilizersPotassium (Potash)
V. Soil FertilityA. FertilizersPotassium (Potash)
* strengthens cell walls and stemsof plants.
V. Soil FertilityA. FertilizersPotassium (Potash)
Sources??
V. Soil FertilityA. FertilizersPotassium (Potash)
* strengthens cell walls and stemsof plants.
* helps in plant respiration and uptake of other minerals.
V. Soil FertilityA. FertilizersB. Organic Matter
V. Soil FertilityA. FertilizersB. Organic MatterC. Lime
D. Other Essential Element for PlantsFe, Cu, Zn Mg, Mn, B, Mo, Cl, S,