Which of the following options includes biofertilisers ?

Options

A. Cowdung manure and farmyard waste
B. A quick growing crop ploughed back into the field
C. Nostoc, Oscillatoria
D. All of these

Answer

C

Explanation

Nostoc and Oscillatoria are nitrogen fixing cyanbacteria. They add organic matter as well as extra nitrogen to the soil. Cyanobacteria are very important and low-cost biofertilisers.