Terrestrial Environment Flashcards
Sorption
Sorption is the association of organic or inorganic
molecules with the solid phase of the soil.
Vadose zone
The vadose zone is defined as the unsaturated
oligotrophic (low in nutrients) environment that lies between surface soil and the saturated zone.
Viable microbes
All the microbes which have life are called viable.
Culturable microbes
Microbes which can be cultured on growth medium (agar medium).
Direct count
It includes viable as well as dead organisms.
Rhizosphere Effect
The distribution of microbes throughout the soil is not even. Microorganisms tend to cluster around the roots of higher plants. This phenomenon is referred to as the rhizosphere effect.
Note
Pore spaces in micro aggregates with neck diameter less than 6 µm have more microbial activity than pore spaces with larger diameter.
Nitrogen assimilation
Inorganic nitrogen compounds such as nitrates, nitrites and ammonia are converted into organic nitrogen compounds such as proteins and nucleic acids in the process of assimilation.
Nitrification
Nitrifying bacteria are responsible for the biological oxidation of ammonia. These bacteria are chemolithotrophs, obtaining chemical energy from the oxidation process. This energy is used to elaborate organic compounds from carbon dioxide.
Aerobic respiration
The process of destroying organic compounds with the aid of O2 is called aerobic respiration.
Bacteria population range
Culture able microbes may range from 10 7
to10 8 g-1 soil while total number of microbes can exceed 10 10
Bacteria have almost 10,000 species in surface soils.
Fungi population range
Number of fungi in surface soils usually range from 10 5 to10 7g-1
Algae population range
Algal population is high in surface 10 cm soil.
Typical algal population close to the surface soil
range from 5000 to 10,000
