Topic: Comparison of Biofertilizer Types
| Feature | Rhizobium | Azotobacter | Azospirillum | Anabaena/Nostoc | Glomus (Mycorrhiza) |
|---|---|---|---|---|---|
| Organism type | Bacterium | Bacterium | Bacterium | Cyanobacterium | Fungus |
| Lifestyle | Symbiotic | Free-living | Rhizosphere-associated | Free-living (aquatic) | Symbiotic |
| Nitrogen fixation | YES (symbiotic) | YES (free-living) | YES (free-living) | YES (in heterocysts) | NO |
| Phosphorus uptake | NO | NO | NO | NO | YES (primary benefit) |
| Host requirement | Legumes only | Not required | Not required | Not required | Broad (many plants) |
| Primary crops | Pea, soybean, groundnut | Wheat, rice, vegetables | Cereals, grasses | Paddy (rice) fields | Broad range |
| NEET trap | Often confused with free-living | Often confused with Rhizobium | Often listed as symbiotic | Often confused with methanogens | Often credited with N2 fixation |
Critical Distinction for NEET:
- Mycorrhiza (Glomus) = PHOSPHORUS (not nitrogen)
- Rhizobium = NITROGEN (symbiotic, legumes only)
- Azotobacter = NITROGEN (free-living, non-legume crops)
- Cyanobacteria = NITROGEN (paddy fields, flooded conditions)