CHAPTER XI 



POTASH MANURES 



MOST of the ordinary crops remove considerable quanti- 

 ties of potash from the land, and any deficiency of this 

 constituent seriously impedes their growth. Natural 

 deficiency of potash is, however, of comparatively rare 

 occurrence, and under ordinary conditions of farming, a 

 large proportion of what is taken out of the land in the 

 crops, is returned in the farmyard manure. Potash 

 manures are not, therefore, so generally necessary, and 

 are not so extensively used as other kinds of artificial 

 manure. Nevertheless they often have a favourable 

 effect, and in some cases are practically indispensable. 

 They are all the more necessary since the use of phos- 

 phatic and nitrogenous manures has become so common. 

 Formerly, when no artificial manures were used, and 

 the sale of produce was more restricted, there was com- 

 paratively little loss. Nowadays, larger crops are raised, 

 more is taken out of the land, and if the margin of 

 available potash be naturally small, it may easily be 

 overpassed and productiveness thereby reduced. 



Potash. The term potash, as now used in agricultural 

 chemistry, always refers to the oxide of potassium (K 2 0). 

 In analyses of soils, manures, etc., the total quantities 

 of potassium compounds found are always so expressed. 

 Such a statement does not necessarily imply that the 

 potassium compounds exist in that form in the substance 

 analysed. For example, it may be said that a sample of 



