Microbe Population in Soil

b.stev

The process of the degradation

of organic material in the

soil and the microbes that

perform these processes

DISCUSSION:

85% dead matter

10% roots of living plants

5% microbes soil & animals

SOILSOIL organismsorganisms that degrade materials:

microbes/ ants/ wormsAnts/ beetles/ microarthropods

Composition of SOIL is:

1. Structures easy to decompose ie:sugars/starch/protein

2. 10 weeks - leaves decompose cellulose (insoluble carbohydrate of

plants)

30 weeks: stem material thinner lignan (complex structure of

wood)

3. 10 years – waxes/ phenols/ lignan

4. HUMUS HUMUS - result of compounds that resist

decomposition and have accumulated in soil

(Soil Health, 2008)

DEGRADATION is a

series of steps that:

break the molecular structureof the organic matter into

smaller & smaller components.

THEN: mineral nutrients are released to the soil

1. chemical alteration occurs2. physical fragmentation3. release of mineral nutrients

3 steps in degradation of organic

matter

(Soil Health, 2008)

ESPECIALLY common microbe in SOIL –

Actinomyces, (genus) SOME strictly DON’T utilise O2

OTHERS can utilise O2 OR chemicals

this MICROBE produces an enzyme – geosmin,

this is the distinct smell given to

TOPSOILTOPSOIL tolerates dry conditions when other microbes can’t

THESE minerals in soil aid the

microbes metabolism; by enabling

the transfer of

electrons within the reactions that

occur

(Soil Health, 2008)

Type & amount of organic matter

Their ability to ADAPT depends upon:

POROSITY

NUTRIENTS

pH 6.0-8.0

TEMPERATURE 15-30o C

contaminants

AVAILABLE O2

(Texas A and M University, 2008)

Other common Microbes in soil:

Bacillus (genus) SUBTILIS

Actinomycete (genus) STREPTOMYCES

Clostridium (genus) PERFRINGENS

MICROBES can quickly adapt &

reach high densities within soil

ORGANIC MATTER ORGANIC MATTER is

degraded by:

lack of replenishment

action of microbes (Wikipedia, 2008)

Bibliography

Soil Health. (2008). Soil organic matter. Retrieved September 21, 2008, from http//:www.soilhealth.com/organic-

Texas A and M University. (2008). Welcome to soil and crop sciences at Texas A and M University. Retrieved September 20, 2008, from http//: www.organiclifestyles.tamu.edu/soil/microbeindex.html - 32k -

Wikipedia. (2008). Soil life. Soil life – wikipedia, the free encylopedia. Retrieved September 24, 2008, from http//:en.wikipedia.org/wiki /Soil_life - 35k -