1. Based on the size
Based on its size, the soil organisms or biological soil bodies were categorized into three groups, namely (1) Makrobia land, if the size above 10 mm, (2) Mesobia, if the size of 0,2- 10 mm, and (3) Microbes, if the size of <0.2 mm (200 mm).
2. Based on How to Acquire Energy
Based on how to obtain energy, soil microorganisms can be divided into two groups, namely (1) phototroph which microorganisms obtain energy from sunlight, and (2) kemotrof that microbes obtain energy from oxidation of inorganic compounds, such as compounds of N (ammonia and nitrite), sulfur, iron or simple carbon compounds, and methane. Also based on the carbon source used, soil microorganisms can be classified into two groups: (1) ototrof or litotrof the group of microorganisms that use CO2, HCO3, CO3 as the carbon source, and (2) heterotrophic or organotrof the group of microorganisms that use organic C as a carbon source.
Microflora belonging phototroph include algae, blue-green bacteria (cianobactery), violet and green bacteria. Microflora belonging fotohetotrof is non-sulfur purple bacteria, and heliobakteri ie bacteria forming endospores, bascilus and clostridium.
Microflora belonging kemoototrof include NH4 + oxidizing bacteria (Nitrobacter), and oxidizing nitrite. Kemoototrof microflora group can be divided into two groups: (1) those that use CO2 include nitrosomonas bacteria, sulfur oxidizing bacteria (Thiobacillus thiooxidans), Fe-oxidizing bacteria (Thiobacillus ferrooxidans) and (2) the groups using HCO 3, for example Pseudomonas sp. While the microflora that includes a group of bacteria perombak kemoheterotrof is cellulose.
3. Based on Existence in Soil
Based on the presence in the soil, soil microorganisms are divided into two major groups: (1) microbial otokton (autochtonous) the microbial local soil-specific soil and or endemic, for example bacteria Azospirillum halopraeferen are always found in soil high salt content (copy), (2) microbial zymogen that microbial growth is influenced by the special treatment such as the addition of fertilizers, organic matter and soil management. In addition it is also known that microbes trasien microbes whose presence in the soil is as a temporary resident. Microbes trasien generally a microbe that is inserted into the ground either intentional or unintentional.
4. Based on the particular function
Based on the specifications of its function, soil microorganisms are classified into two main groups, namely
(A) specific microorganisms in the soil functional if its function is specific, such as bacteria nitrosomonas and nitrobacter role in nitrification, Rhizobium bacteria that play a role in the fixation of N-free, endomikoriza that play a role in the provision and uptake of P by plants.
(B) non-specific microorganisms are functional if not specific role, for example, microbial decomposers of organic material.
5. Based on Its Effect on Plant Growth
If it is associated with the growth of plants, the soil microorganisms are grouped into three groups, namely, (1) the beneficial biota, (2) adverse biota, (3) without the influence of biota. If in a country, where groups of beneficial microorganisms in the soil dominant in number, then good plant growth. If the group mikroornanisme adverse dominant presence in the soil, plant growth will be ugly.
For the purpose of that beneficial soil microorganisms amount can be maximized, and that harm can be minimized, and that without the influence of microbes can be utilized, so that growth and crop production can be optimized, the development of biological and biotechnological soil becomes important to be developed as the basis for organic farming.
Figure 1. Organic Farming 34. Using Manure