4 o 



Potash Fertilisers. 



[APRIL, 



POTASH FERTILISERS: 



THEIR VARIETIES, COMPARATIVE VALUE, AND 

 APPLICATION. 



The more usual potash fertilisers are Kainit, Muriate of 

 Potash and Sulphate of Potash, together with " Potash Salts " 

 of varying percentages, and Blast Furnace Flue Dust. All 

 potash manures should be valued according to their content of 

 potash (K 2 O), but in the case of muriate of potash the percent- 

 age of chloride of potash (KC1) and in the case of sulphate of 

 potash the percentage of sulphate of potash (K 2 S0 4 ), are 

 sometimes quoted. Invoices, however, should always state the 

 percentage of potash (K 2 0). 



In order to compare the values of the different forms of potash 

 manures, it is customary to divide the price per ton by the 

 percentage of potash. The result is called the " unit price," 

 which forms the best basis of comparison. On the basis of the 

 market prices shown below, the " unit prices " will be found to 

 work out as follows : — 





Potash K a O. 

 Per cent. 



Price 

 Per Ton. 



Unit Price. 







£ s. d. 



5. d. 



Kainit 



14 



700 



10 



Potash Salts 



30 



12 15 



8 6 



*Muriate of Potash, 80 per cent. 





KC1 = 



50 



20 17 6 



8 4 



* Sulphate of Potash, 90 per cent. 









K 2 S0 4 = 



49 



23 7 6 



9 6 



* To reduce chloride of potash (KC1) to potash (K 2 0), multiply by 94 

 and divide by 149. To reduce sulphate of potash (K ;2 S0 4 ) to potash, multiply 

 by 94 and divide by 174. The reason for this rule is that it takes 149 lb. of 

 KC1 or 174 lb. of K 2 S0 4 to supply 94 lb. of K 2 0. 



Fertilising Value. — The relative quantities of each manure to 

 be applied will depend mainly on the percentage of potash, 

 though there may be reasons, referred to below, for preferring 

 one form of potash to another. 



Sulphate of potash, it will be noticed, is 3 J times as rich in 

 potash as kainit, and, therefore, 3 J cwt. of kainit would need 

 to be used in place of 1 cwt. of sulphate of potash, and, con- 

 versely, where 1 cwt. of kainit is required, only 32 lb. of sulphate 

 would be needed. 



This can be expressed in tabular form. By reading the 

 following columns downwards the amount in pounds of any one 

 manure equal to 1 cwt. (112 lb.) of any other manure can be 



