Symbiotic and nonsymbiotic nitrogen fixation in grassland and forest and its importance in soil

The data with regard to nitrogen fixation by legumes and non legumes (nodulated) showed that cultivation of peas in pastures field fixed atmospheric N₂ in the range of 400–500 kg ha⁻¹ with maximum fixation through leucaena leucocephala. Among the non legumes (nodulated), alnus and casuarineas species had prominent place in N₂ fixation varying from 60–160 kg ha⁻¹ year⁻¹. On an average, Azotobacter species fixed 10–50 kg N₂ under various environmental conditions. Higher efficiency of N₂ fixation was noticed in Azotobacter and Beijerinckia isolates from soils of grass lands than counterparts of other types of kothikorh profile (Kangra, HP) under Cedrus deodara depicted variable amount of N₂ fixation as was observed in associate nitrogen fixing bacteria. As mentioned, application of Rhizobium biofertilizer alone or in combination with Azotobacter proved useful in increasing nodulation and growth of seven forest species. The efficiency of inoculants was further enhanced due to pelleting of inoculated seeds with lime. The use of Azotobacter culture promoted the growth of Querus serrata and mulberry seedlings.