492 THE POTATO 



"The kainit and Thomas meal were applied in 

 the fall and the nitrate was strewn in the spring. 

 Instead of nitrate, sulphate of ammonia was also 

 used. No mention is made of superphosphates as 

 having been used in these experiments, although 

 farmers employ them to a very large extent. 

 Kainit is a mixture of sulphate of potash and sul- 

 phate of magnesia with variable proportions of 

 chlorure of magnesium and marine salt. The 

 useful substance in this combination is the potash 

 which is represented by a proportion of 12.96 per 

 100. As the chlorure of magnesium is a salt de- 

 structive to vegetation, the use of raw kainit is not 

 recommended. As a rule it is sold in prepared 

 form after having been calcined, whereby the 

 chlorure is eliminated. 



"Thomas meal is a fertilizer made from basic 

 slag. Concerning Chilean nitrate of soda it is 

 scarcely necessary to speak. In respect to this 

 fertilizer, C. V. Garola says that it is not an in- 

 dispensable fertilizer, and need not be employed 

 unless it furnishes a pound of azote at a cost in- 

 ferior to that of other fertilizers containing azote, 

 such as blood, horns, flesh, and, particularly, sul- 

 phate of ammonia. 



"Mr. Garola, already quoted, in his 'Ten Years of 

 Agricultural Experiments' says in regard to the ef- 

 fect of fertilizers upon the cultivation of potatoes : 

 'The potato is always very grateful for the ma- 

 nure that it receives. A strong manure, well pre- 

 pared, is the first condition to a good crop. By 

 using it to an extent of thirty tons (the author does 

 not state over what area) I have obtained an in- 

 crease of 88 per cent, in the yield; and a small dos- 

 ing of manure, completed by super-phosphate and 

 nitrate of soda, increased the crop by 105 per cent. 



