Which one of the following is not a biofertilizer?

Which of the following is used as biofertiliser?

$I.$ Cyanobacteria

$II.$ Yeast

$III.$ Symbiotic bacteria

$IV.$ Free living bacteria

Choose the correct option

Agricultural chemicals include

Which of the following is not a symbiotic nitrogen fixing bacterium?

Azolla enriches rice fields with nitrogen due to its association with

A nitrogen fixing bacterium that forms a loose assocation with the roots of crop plants is