N2 has a strong triple covalent bond, and higher plants do not have the ability to break this bond directly. The availability of nitrogen to plants can be a limiting factor in agricultural production. As a result, producers will often add nitrogen to the soil to meet nitrogen requirements for crops. The process where molecular nitrogen is changed into ammonia or nitrate is known as nitrogen fixation. This can be done through industrial processes.
Producers can then add a chemical fertilizer to soils to provide a source of nitrogen.
However this can be costly and over-application can lead to waste and pollution. There are also natural processes which result in nitrogen fixation. Certain microorganisms can also fix nitrogen. These microorganisms contain enzyme systems that can catalyze chemical reactions to break the N2 triple bond. The relationship between the plant and the bacteria is known as a symbiotic relationship since both the plant and the bacteria benefit from their relationship.