Blue-green algae increase the concentration of which substances in the soil?

What is the main source of biofertilizers?

The best biofertilizer for paddy (rice) cultivation is:

Identify the correct statements regarding mycorrhiza:
$(1)$ Many members of the genus $Glomus$ form mycorrhiza.
$(2)$ It is responsible for all mineral absorption from the soil.
$(3)$ Such associations show benefits against drought and salinity in plants.
$(4)$ Mycorrhiza is a symbiotic association between fungi and roots of higher plants.

Which one of the following is not used in organic farming?

Which of the following is a biofertilizer reported to increase rice production by more than $50\%$?