Various leguminous plants like Crotalaria juncea, Cassia mimusoides, Glycine max, Indigofera linifolia, Sesbania rostrata, Acacia nilotica, Leucena, Lathyrus and Mucuna are used as green manures.
They accumulate more than 80 Kg of nitrogen per hectare in the soil when grown as green manures. Azolla is an aquatic fern, which contains an endophytic cyanobacterium Anabaena azollae in its leaves.
It is used as a biofertilizer in rice field. Out of six species of Azolla, A. pinnata is widely employed as a successful biofertilizer in Indian rice fields. It adds 30 Kg of nitrogen per hectare where the yield is equivalent to that of urea or ammonium phosphate.
Mycorrhiza as biofertilizer
Mycorrhiza is a root inhabiting fungus found around or inside the
roots of many plants. It increases growth and yield and also provides protection to the roots against edaphic (soil) stresses, pathogen and pests.
Helps in the increased uptake of soil and mineral water solution by the plant root system. It provides many uses for the host plants eg. VAM (Vesicular Arbuscular Mycorrhiza) fungi. Mycorrhiza is of two types.
a. Ectotrophic mycorrhiza, which are found only outside the surface
of roots of plants. eg. Basidiomycetous fungi.
b. Endotrophic mycorrhiza, which are found inside the roots, in the
intercellular spaces and even inside the cell (intra and intercellular)
eg. VAM fungi.