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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 −).
Plant nutrition is the study of the chemical elements and compounds necessary for plant growth and reproduction, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element is part of some essential plant constituent or metabolite .
However, the excessive or inefficient use of nitrogen fertilizers can lead to environmental problems such as nitrogen leaching, runoff, and emissions of nitrogen oxides (NOx). [4] Nitrogen leaching occurs when nitrogen compounds, primarily nitrates , move through the soil profile and enter groundwater, potentially contaminating drinking water ...
Nitrogen and potassium are also needed in substantial amounts. For this reason these three elements are always identified on a commercial fertilizer analysis. For example, a 10-10-15 fertilizer has 10 percent nitrogen, 10 percent available phosphorus (P 2 O 5) and 15 percent water-soluble potassium (K 2 O). Sulfur is the fourth element that may ...
A nutrient cycle (or ecological recycling) is the movement and exchange of inorganic and organic matter back into the production of matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic.
Although nitrogen makes up most of the atmosphere, it is in a form that is unavailable to plants. Nitrogen is the most important fertilizer since nitrogen is present in proteins (amide bonds between amino acids), DNA (puric and pyrimidic bases), and other components (e.g., tetrapyrrolic heme in chlorophyll). To be nutritious to plants, nitrogen ...
Some nitrogen originates from rain as dilute nitric acid and ammonia, [44] but most of the nitrogen is available in soils as a result of nitrogen fixation by bacteria. Once in the soil-plant system, most nutrients are recycled through living organisms, plant and microbial residues ( soil organic matter ), mineral-bound forms, and the soil solution.
It is essential that plants uptake nitrogen from the soil or rely on symbionts to fix it from the atmosphere to assure growth, reproduction and long-term survival. Another way nitrogen affects soil respiration is through litter decomposition. High nitrogen litter is considered high quality and is more readily decomposed by microorganisms than ...