Azolla

Azolla is a fast growing aquatic plant often observed in many water bodies. It itself is not much useful, except that it can add organic matter on decomposition. But an algae called Anabaena Azollae inhabits in the cavities of Azolla leaves and fix atmospheric nitrogen. Thus, Azolla leaves acts as excellent source of nitrogen, besides their capacity to act as source of organic matter.

Use of Azolla is standardised and recommended in paddy cultivation mainly due to aquatic condition prevailing in paddy fields. Before paddy seedlings are transplanted, Azolla is grown for 40 - 45 days in standing water and on full leaf growth, they are dried and incorporated in soil. Use of Azolla is reported to have increased the yields of paddy by 30 - 35%.