Labeling of Chemical Fertilizer
The labeling of fertilizers varies. In most countries the macronutrients are labeled with an NPK analysis (in Australia, "N-P-K-S" adding sulfur).
The three numbers on the fertilizer label represent an analysis of the composition by weight. These three numbers correspond to nitrogen, phosphorus, and potassium (N-P-K) and always appear in that specific order. When a 4th number is included, it indicates the sulfur content (N-P-K-S).
While the number for "N" represents the percentage weight of nitrogen, in some European countries, the other two components are not for the analysis of the element, but rather, the analysis of the "available" or "soluble" form of the element. In traditional chemical analysis, the tests used treated the sample so as to measure the equivalent P2O5 and K2O. For instance, some potassium-bearing rocks do not count as having available potassium.
Similarly the number for "P" in some countries is actually the weight of an equivalent quantity of P2O5 whereas in others (including Australia) it refers to elemental phosphorus. In order to calculate the weight of P in the formulation, the weight of P2O5 can be multiplied by 0.44 to compensate for the weight of the oxygen in the molecule. For example, a bag of 10-10-10 has 10 pounds of nitrogen, 10 pounds of P2O5, but only 4.4 pounds of P.
Likewise, the number for "K" in Europe can refer to the weight of an equivalent quantity of K2O, whereas in Australia it refers to elemental potassium. In order to calculate the weight of K in the formulation, the weight of K2O can be multiplied by 0.83 to compensate for the weight of the oxygen in the molecule. For example, a bag of 10-10-10 has 10 pounds of K2O, but only 8.3 pounds of K.
As an example, the fertilizer potash (in modern times, muriate of potash or potassium chloride) is composed of 52% potassium and 48% chlorine by weight; chemical analysis of 100g of potassium chloride (KCl), would show 63g of equivalent potassium oxide (K2O) when done in the manner of fertilizer analysis. The percentage yield of K2O from the original 100g of fertilizer is the number shown on the label. A potash fertilizer would thus be labeled 0-0-63, and not' (except in Australia and some other countries) ' 0-0-52.
Read more about this topic: Fertilizer
Famous quotes containing the words labeling, chemical and/or fertilizer:
“Although adults have a role to play in teaching social skills to children, it is often best that they play it unobtrusively. In particular, adults must guard against embarrassing unskilled children by correcting them too publicly and against labeling children as shy in ways that may lead the children to see themselves in just that way.”
—Zick Rubin (20th century)
“If Thought is capable of being classed with Electricity, or Will with chemical affinity, as a mode of motion, it seems necessary to fall at once under the second law of thermodynamics as one of the energies which most easily degrades itself, and, if not carefully guarded, returns bodily to the cheaper form called Heat. Of all possible theories, this is likely to prove the most fatal to Professors of History.”
—Henry Brooks Adams (1838–1918)
“...I was confronted with a virile idealism, an awareness of what man must have for manliness, dignity, and inner liberty which, by contrast, made me see how easy living had made my own group into childishly unthinking people. The Negro’s struggles and despairs have been like fertilizer in the fields of his humanity, while we, like protected children with all our basic needs supplied, have given our attention to superficialities.”
—Sarah Patton Boyle, U.S. civil rights activist and author. The Desegregated Heart, part 1, ch. 19 (1962)