Immobilization refers to –

Correct option is B

· Immobilization: It is the conversion of inorganic nitrogen (N) into organic nitrogen by soil microorganisms.
· Process Overview:
· Soil microorganisms utilize inorganic nitrogen (e.g., nitrate, ammonium) for their growth.
· This nitrogen is then converted into organic forms and incorporated into microbial biomass.
· Importance of Immobilization:
· Prevents nitrogen loss from leaching or volatilization.
· Temporarily reduces plant-available nitrogen.
· Other Options Explained:
· (a) Conversion of organic N to inorganic form: Refers to mineralization, not immobilization.
· (c) Fixation by clay: Refers to physical binding of ions by soil clay particles.
· (d) Accumulation by plant: Describes plant nitrogen uptake, not immobilization.
· Therefore, Conversion of inorganic N to organic form (Option B) is the correct answer.