Explanation

Nitrogen fixation refers to the process of converting atmospheric nitrogen (N2) into a usable form for plants.

This can happen through several methods: 

Atmospheric fixation:

• This occurs naturally when lightning strikes, breaking the strong nitrogen-nitrogen triple bond and creating nitrogen oxides that can dissolve in rainwater.

Industrial fixation:

• This involves using high-temperature and pressure processes, like the Haber-Bosch process, to convert nitrogen into ammonia.
• This method is crucial for industrial agriculture. 

Biological fixation:

• This process is carried out by certain bacteria, such as those found in the root nodules of legumes (like peas and beans), or free-living bacteria in the soil.
• These bacteria can break down the nitrogen molecule and convert it into ammonia or other usable nitrogen compounds.