Simplify the following text for a Grade 7 native English-speaking person.
Original: The conversion of nitrogen ( N2 ) from the atmosphere into a form readily available to plants and hence to animals and humans is an important step in the nitrogen cycle , which distributes the supply of this essential nutrient . There are four ways to convert N2 ( atmospheric nitrogen gas ) into more chemically reactive forms :
Simplified: Nitrogen fixation is needed to change the nitrogen in air ( N2 ) into forms that can be used by life .