Q. A water fern, which is used as a green manure in rice fields is

A) Salvinia
B) Mucor
C) Aspergillus
D) Azolla
Explanation

Azolla is cultivated in rice fields as it provides both green compost and fixed nitrogen to the crop. The use of Azolla in rice fields at the rate of 200 gm per square metre area can increase rice yield by 12.38%. Eexperiments have revealed that application of 10 tonnes of fresh Azolla biomass in one hectare, adds as much as 100 kg nitrogen.

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.