POTATOES 351 



such a fertilizer should contain a proportionately small amount of 

 nitrogen, but should be very rich in potash. Whatever the soil, 

 the potato crop seems to be benefited by a heavy application of 

 potash. A fertilizer carrying 3 or 4 per cent of nitrogen, from 

 6 to 8 per cent of phosphoric acid, and from 8 to 10 per cent of 

 potash is the usual combination ; but, as suggested above, it should 

 be the aim of the grower to obtain his nitrogen supply through the 

 use of leguminous crops rather than by purchase in the form of a 

 chemical. There may be an exception to this in localities with very 

 short growing seasons, in which case quick-acting forms of nitrogen, 

 such as nitrate of soda or sulphate of ammonia, would be preferable 

 to the slower-acting organic forms. If it is desired to buy the in- 

 gredients separately and combine them at home, the following 

 formulas will be found fairly satisfactory : 



I. Nitrogen in the form of dried blood containing 13 per 



cent nitrogen .'.. . . ... . . 600 Ib. 



Phosphoric acid in the form of i6per cent acid phosphate. 1000 Ib. 

 Potash in the form of high-grade sulphate of potash con- 

 taining 50 per cent potash 400 Ib. 



This mixture contains 3.9 per cent nitrogen, 8 per cent available 

 phosphoric acid, and 10 per cent potash. 



II. Nitrogen in the form of sulphate of ammonia containing 



20 per cent nitrogen 200 Ib. 



Nitrogen and phosphoric acid in the form of dried fish 

 scrap containing 8 per cent nitrogen and 8 per cent phos- 

 phoric acid 500 Ib. 



Phosphoric acid in the form of 16 per cent acid phosphate. 900 Ib. 

 Potash in the form of high-grade sulphate of potash con- 

 taining 50 per cent potash 400 Ib. 



This mixture contains 4 per cent nitrogen, 9.2 per cent available 

 phosphoric acid, and 10 per cent potash. 



III. Nitrogen in the form of nitrate of soda containing 16 per 



cent nitrogen 200 Ib. 



Nitrogen, phosphoric acid, and potash in the form of cotton- 

 seed meal containing 7 per cent nitrogen, 2 per cent phos- 

 phoric acid, and 2 per cent potash 600 Ib. 



Phosphoric acid in the form of 16 per cent acid phosphate . 850 Ib. 

 , Potash in the form of high-grade sulphate of potash con- 

 taining 50 per cent potash 350 Ib. 



This mixture contains 3.7 per cent nitrogen, 7.4 per cent avail- 

 able phosphoric acid, and 9.4 per cent potash. 



