Question

Describe soil and soil microbe contribution to the biogeochemical cycle. Define rhizospere?

Answer 1

Soil- the porus fine particles of rocks,formed by pedogenesis over a long period of time,it is the rich source of both organic and inorganic matters.

Formation of soil- 1.weathering of rocks

A.physical weathering

B.chemical weathering

C.biological weathering

Soil-microbe contribution in bio geochemical cycles:-Soil is mixed natural resource for various minerals as it is rich in organic and inorganic matters. Soil is essential part of various bio geochemical cycles, like:- nitrogen , sulphur, phosphorus cycles.

Soil is rich source of various microbes which are part of nitrogen cycle . Bacteria like Rhizobium present in root nodules of legumes able to fix atmospheric nitrogen in form of nitrogenous compounds by the process of biological nitrogen fixation. Some other microbes like nitrobactor, nitrocystis, nitrosomonas, pseudomonas helps in fixation of nitrogenous compounds in one or other forms.

1. Atmospheric nitrogen converted into ammonia by rhizobium,

2. Ammonia into nitrite by nitrosomonas,

3. Nitrite into nitrate by nitrobactor ,

4. Nitrate into atmospheric nitrogen by pseudomonas.

RHIZOSPHERE- the narrow region of soil- that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome.

As plant roots grow through soil they mostly release water soluble compounds such as amino acids, sugars and organic acids that supply food for the microorganisms.

Rhizosphere play an important role in regulating soil organic matter decomposition and nutrient cycling.

Rhizosphere processes are major gateways for nutrients and water.