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Labeling of fertilizer
The labeling of fertilizers varies by country in terms of analysis methodology, nutrient labeling, and minimum nutrient requirements. The most common labeling convention shows the amounts of nitrogen, phosphorus, and potassium in the fertilizer. ==Labeling of macronutrient fertilizers== Macronutrient fertilizers are generally labeled with an ''NPK'' analysis, based on the relative content of the chemical elements nitrogen (N), phosphorus (P), and Potassium (K) that are commonly used in fertilizers. However, numbers used in this labeling scheme do not directly represent the source composition or absolute nutrient content of the fertilizer. The N value is the percentage of elemental nitrogen by weight in the fertilizer. The value for P is the fraction by weight of P2O5 in a fertilizer with the same amount of phosphorus that gets all of its phosphorus from P2O5. The value for K is analogous, based on a fertilizer with K2O.〔() 22 October 2014〕 For example, the fertilizer ''potash'' is a naturally occurring mineral consisting of nearly pure potassium chloride (''KCl''). As such, it contains one potassium atom for every chlorine atom, and is 52% potassium and 48% chlorine ''by weight'' (because of the difference in atomic weights of the elements). K2O is similarly 83% potassium. To have 52% potassium, therefore, a fertilizer that gets all its potassium from K2O would have to be 63% K2O (.52/.83 is .63). Pure KCl fertilizer would thus be labeled 0-0-63; because potash is less than pure (it contains other compounds that contain no potassium), potash is labeled 0-0-60.
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「Labeling of fertilizer」の詳細全文を読む
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