Biology XI: 12 Mineral Nutrition(4 Nitrogen Cycle)

Nitrogen Cycle Nitrogen Metabolism Nitrogen is a limiting nutrient in agricultural and natural systems as plants compete with microbes for nitrogen present in soil. Nitrogen fixation: Process of conversion of nitrogen (N2) into ammonia (NH3) Ammonification: Decomposition of organic nitrogen of plants and animals into ammonia The ammonia so formed may volatilise and re-enter the atmosphere, or some of the ammonia may be converted into nitrate by soil bacteria. These are the steps involved in nitrification.Nitrifying bacteria are chemoautotrophs. The nitrate so formed can be easily absorbed by the plants, and transported to leaves. In leaves, nitrate is reduced to ammonia to form the amine group of amino acids. Denitrification: Process of reduction of the nitrate present in soil to nitrogen. Carried out by bacteria like Pseudomonas and Thiobacillus