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Nitrogen is shown to be one of the fundamental elements in the composition of living systems.
He is involved with the coordination and control of metabolic activities. However, although 78% of the atmosphere consists of nitrogen, the vast majority of organisms are unable to use it because it is in gaseous form (N2) which is very stable having little tendency to react with other elements.
Consumers get nitrogen directly or indirectly from producers. They take advantage of nitrogen found in amino acids. Producers introduce nitrogen into the food chain through the use of inorganic forms found in the environment, mainly nitrates (NO3) and ammonia (NH3+). The nitrogen cycle can be divided into some steps:
• Fixation: It consists in the transformation of gaseous nitrogen into substances usable by living beings (ammonia and nitrate). The organisms responsible for the fixation are bacteria, they remove nitrogen from the air causing it to react with hydrogen to form ammonia.
• Ammonification: Part of the ammonia present in the soil originates from the fixation process. The other comes from the process of decomposition of proteins and other nitrogen residues, contained in dead organic matter and excreta. Decomposition or ammonification is performed by bacteria and fungi.
• Nitrification: It is the name given to the process of converting ammonia to nitrates.
• Denitrification: Denitrifying bacteria (such as Pseudomonas denitrificans), are able to convert nitrates into molecular nitrogen, which returns to the atmosphere closing the cycle.
A widely used procedure in agriculture is “crop rotation”, which alternates the planting of non-legumes (maize, for example), which remove nitrogenous nutrients from the soil, with legumes (beans) that return these nutrients. to the middle.