The most abundant source of nitrogen is nitrogen gas (N2) that is found in the atmosphere.
However, plants can only absorb nitrates from
the soil, they cannot take in nitrogen gas. Your
lungs are not adapted to take in nitrogen gas
either. You get your nitrogen from eating plants
or plant eaters that got their nitrogen as nitrates
(NO3) in soil. But one category of living thing can
get nitrogen from the air and turn it into nitrogen.
Another population in the same category can
turn nitrogen compounds from dead organisms
back into nitrogen gas. IDENTIFY the name of the
population of organisms that can provide usable
nitrogen for all the other living things on earth,