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All plants require sufficient supplies of macronutrients for healthy growth, and nitrogen (N) is a nutrient that is commonly in limited supply. Nitrogen deficiency in plants can occur when organic matter with high carbon content, such as sawdust, is added to soil.〔http://whatcom.wsu.edu/ag/compost/fundamentals/needs_carbon_nitrogen.htm〕 Soil organisms use any nitrogen to break down carbon sources, making N unavailable to plants.〔 This is known as "robbing" the soil of nitrogen. All vegetables apart from nitrogen fixing legumes are prone to this disorder. Nitrogen deficiency can be prevented in the short term by using grass mowings as a mulch, or foliar feeding with manure, and in the longer term by building up levels of organic matter in the soil. Sowing green manure crops such as grazing rye to cover soil over the winter will help to prevent nitrogen leaching, while leguminous green manures such as winter tares will fix additional nitrogen from the atmosphere. ==Symptoms== Some symptoms of nitrogen deficiency (in absence or low supply) are given below : #The chlorophyll content of the plant leaves is reduced which results in pale yellow colour. Older leaves turn completely yellow. #Flowering, frutings, protein and starch contents are reduced. Reduction in protein results stunted growth and dormant lateral buds. 〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「nitrogen deficiency」の詳細全文を読む スポンサード リンク
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