Assertion: nitrogen | /r/HasProperty | fixed
Facets:
Source sentences:
text: Nitrogen is fixed, or combined, in nature as nitric oxide by lightning and ultraviolet rays, but more significant amounts of nitrogen are fixed as ammonia, nitrites, and nitrates by soil microorganisms.
text: After nitrogen has been fixed, other bacteria convert it into nitrate, in a process known as nitrification.
text: Nitrogen is "fixed" from the atmosphere by bacteria in the roots of certain plants such as clover.
text: Nitrogen has to be 'fixed' or bound into another form for animals and plants to use it.