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Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that can fix nitrogen gas (N 2) depend on the ability to assimilate nitrate or ammonia for their needs. Other organisms, like animals, depend ...
Plants are made up of four main elements: hydrogen, oxygen, carbon, and nitrogen. Carbon, hydrogen, and oxygen are widely available respectively in carbon dioxide and in water. Although nitrogen makes up most of the atmosphere, it is in a form that is unavailable to plants.
Plants that contribute to nitrogen fixation include those of the legume family—Fabaceae— with taxa such as kudzu, clover, soybean, alfalfa, lupin, peanut and rooibos. [45] They contain symbiotic rhizobia bacteria within nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. [64]
Nitrogen is the most critical element obtained by plants from the soil, to the exception of moist tropical forests where phosphorus is the limiting soil nutrient, [36] and nitrogen deficiency often limits plant growth. [37] Plants can use nitrogen as either the ammonium cation (NH 4 +) or the anion nitrate (NO 3 −).
Even though nitrogen is a necessary element for life, too much of it in water can have negative effects on aquatic ecosystems and endanger human health. Agricultural runoff, where fertilizers containing nitrogen compounds can seep into rivers, lakes, and groundwater, is one of the main sources of nitrogen in water.
Nitrogen fertilizer being applied to growing corn in a contoured, no-tilled field in Iowa.. Nutrient management is the science and practice directed to link soil, crop, weather, and hydrologic factors with cultural, irrigation, and soil and water conservation practices to achieve optimal nutrient use efficiency, crop yields, crop quality, and economic returns, while reducing off-site transport ...
Reverse fuel cell [79] technology converts electric energy, water and nitrogen into ammonia without a separate hydrogen electrolysis process. [80] The use of synthetic nitrogen fertilisers reduces the incentive for farmers to use more sustainable crop rotations which include legumes for their natural nitrogen-fixing ability.
In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in a maximum overall photosynthetic efficiency of 3 to 6% of total solar radiation. [1]