The answer is - it can not be taken out of the atmosphere.
The nitrogen, even though makes for about 78% of our atmosphere, and is by far the most abundant gas in it, we can not use it because it can not be taken out of the atmosphere as it is. If we take nitrogen in the form as it is in the atmosphere it is useless for both, humans and plants. It has to go through a process of ''fixation'' first before we can actually use it in our food.
Explanation:
Weathering is the breaking down or dissolving of rocks and minerals on Earths surface. Once a rock has been broken down, a process called erosion transports the bits of rock and minerals away. Water, acids, salt, plants, animals, and changes in temperature are all agents of weathering and erosion.