Which of the following is free living aerobic and nonphotosynthetic nitrogen fixing bacterium

Aquatic fern which is an excellent biofertilizer

Symbiotic nitrogen fixation in root nodules of some legumes is caused by

Why are blue green algae not popular as biofertilisers ?

Which of the following are the part or example of symbiotic mutualistic association?

$I.$ Yeast

$II.$ Rhizobium

$III.$ Mycorrhiza

$IV.$ Oscillatoria

Biofertilisers include