Which fungus is taking part in the formation of mycorrhiza?

Which organism is highly useful for soil fertility?

Farmers have reported over $50\%$ higher yields of rice by using which of the following biofertilizer?

Which of the following is used as biofertiliser?
$I.$ Cyanobacteria
$II.$ Yeast
$III.$ Symbiotic bacteria
$IV.$ Free living bacteria
Choose the correct option.

The phosphorus-rich fertilizer obtained from sea birds along the coast of Chile and Peru is:

Which one of the following is not a biofertiliser?