STD 12 - 8. microbes in human welfare — Biology STD 12 Science — Question

b
(b) : Azolla plays a very important role in rice production. Azolla and its nitrogen­fixing partner, Anabaena, have been used as green manure to fertilise rice paddies and increase production. With the help of Azolla, rice can be grown year after year, several crops a year, with little or no decline in productivity; hence no rotation of crops is necessary.