Atmospheric nitrogen can only be used by most living things after it has been converted to nitrates with the help of nitrogen-fixing bacteria during the process of nitrogen fixation converted to nitrates with the help of nitrogen-fixing bacteria during the process of nitrogen fixation, converted to ammonia by bacteria of decay converted to ammonia by bacteria of decay, taken in by plants through the lenticels by nitrogen fixation taken in by plants through the lenticels by nitrogen fixation, combined with carbon dioxide to form protein