Symbiotic Biological Nitrogen Fixation

Describe the process of symbiotic bilogical nitrogen fixation.

Nitrogen fixation is

Hydroponics|Nitrogen Metabolism|Biological Nitrogen Fixation|Nodule Formation|OMR

Nitrogen Fixation | | Biological nitrogen Fixation | | Abiological nitrogen Fixation

Mechanism OF biological Nitrogen Fixation | | Rhizobium and legume symbiosis

What is meant by biological nitrogen fixation ? List atleast two organisms involved in biological nitrogen fixation.