Nitrogen fixation is the process of converting nitrogen gas from the air into compounds that plants can use to grow. While nitrogen makes up about 78% of the air we breathe, plants can't use it in that form. They need it transformed into different chemical compounds first, and that transformation is nitrogen fixation.

Certain bacteria perform this vital process naturally. Some live in the soil, while others live in special bumps called nodules on the roots of plants like beans, peas, and clover. These bacteria act like tiny chemical factories, taking nitrogen from air pockets in the soil and converting it into ammonia and other compounds that plants can absorb through their roots. Without nitrogen fixation, most plants couldn't get enough nitrogen to make the proteins they need to grow.

Farmers have known for centuries that planting beans or peas makes soil more fertile for next year's crops, though they didn't understand why until scientists discovered nitrogen fixation. Today, factories also perform nitrogen fixation artificially to make fertilizers, helping farmers grow more food. This industrial process, called the Haber-Bosch process, mimics what bacteria do naturally but requires tremendous heat and pressure.