Potash removed in Crops.
The amount of potash removed by the different crops from the soil will be considered in a subsequent chapter. We need only say here that the class of crops which remove the largest quantity are the root crops, especially mangels. The loss is least in the case of the cereals. The amount of potash contained in the straw of cereals is about three times the amount of that removed in the grain.
Potash removed in Milk.
Lastly, we may refer to the potash removed in milk, which, on an average, may be taken at 10 lb. per annum for each cow.
Potash Manures.
Of potash manures the chief are the sulphate and the chloride, or, as it is commercially known, the "muriate." The chief source of potash manures are the Stassfurt deposits already referred to. Wood-ashes have also been used in large quantities in the past (chiefly as a potash manure), and in some parts of the world are still used. A considerable source of artificial potassic manures is the refuse manufacture of sugar-beet, such a large industry in Germany. Potash occurs as a constituent of certain other manures, more valuable for nitrogen and phosphoric acid, such as guano and dried blood.
FOOTNOTES:
[126] According to Boguslawski and Dittmar, the total amount of potash calculated as sulphate of potash in salt water equals 1141 × 1012 tons.
[127] See Storer's 'Agricultural Chemistry,' vol. ii. p. 291.
[128] See Appendix, Note I., p. 220.