Nitrogen is returned to the atmosphere in the process of

Through denitrification. Nitrates are converted back to N2 gas by denitrifying bacteria. N2 gas is also returned to the atmosphere through volcanos.Explanation:simple science

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.