220 Practical Farming 



should always be in the form of a high-grade sulphate. 

 While the potash in the crude form of kainit is a sulphate 

 it is associated with such a large percentage of salt that 

 it acts as a chloride. Hence, only the high-grade sul- 

 phate that is comparatively free from chlorides should be 

 used in the preparation of a tobacco fertihzer. 



Of course, the amount of a fertilizer to be used will de- 

 pend very largely on the fertility of the soil, but the pro- 

 portions of the materials will be the same in any event. 

 We have seen a formula proposed for tobacco growers 

 which contains 8 per cent, of phosphoric acid, 2 per cent, 

 of ammonia, and 10 per cent, of potash. This is a badly 

 constructed formula, for while the percentage of potash is 

 all right the percentages of phosphoric acid and ammonia 

 are wrong. Two per cent, of ammonia would be a very 

 small percentage of nitrogen, since ammonia is a hydride 

 of nitrogen. The nitrogen should appear as nitrogen 

 and not as ammonia, for we want the actual amount of 

 nitrogen rather than that of ammonia to be stated. Then 

 the percentage of phosphoric acid is too high. The effect 

 of an excess of phosphoric acid in a tobacco fertilizer will 

 be shown in what the growers call a *'bony" leaf. The 

 plant needs nitrogen to some extent in the immediately 

 available form of a nitrate to start it off early, and the 

 greater part in the form of organic nitrogen to keep up 

 the growth by becoming available during the growth of 

 the crop. 



The following formula is the result of long and pa- 

 tiently investigated experiments, and in practice in the 

 bright cigarette types of tobacco, has proved to produce 

 the highest priced tobacco of the season: 



