The atmosphere contains about 80% Nitrogen gas but nitrogenIn this form cannot be used by plants Which process convert atmospheric nitrogen to a useful form for plants

The atmosphere contains about 80% nitrogen gas but nitrogen in this form cannot be used by plants. The process which convert atmospheric nitrogen to a useful form for plants is known as nitrogen fixation.

Explanation:

The process which convert atmospheric nitrogen to a useful form for plants is known as nitrogen fixation. The three major ways of nitrogen fixation are; by bacteria living in the soil, by lightning and by industrial methods. The majority of nitrogen fixation is done by symbiotic bacteria (eg: Rhizobium living in leguminous plant nodules) or free-living non-symbiotic bacteria (cyanobacteria, azotobacter etc). The nitrogenase enzyme in these bacteria converts gaseous nitrogen into ammonia. The soil living bacteria, such as nitrobacter convert this ammonia into nitrites and then nitrates, which are the biologically useful forms that can be absorbed by plants. The conversion of ammonia into nitrate is called nitrification.

When lightning occurs, the enormous energy produced by lightning flash breaks apart the nitrogen in the atmosphere into nitrogen atoms, which combines with atmospheric oxygen to form nitrates. During rain, these nitrates get dissolved and upon reaching the ground get released into the soil. Some chemical plants also manufacture fixed nitrogen for fertilizers.