COMMERCIAL FERTILIZERS 107 



129. The use of potash. Potash fertilizers are used in the 

 United States mainly in mixed fertilizers and on special crops, 

 such as potatoes and tobacco, which require much potassium 

 in their growth. In European countries near the potash mines 

 they are used more extensively on general crops. The forms 

 having the widest use are the chloride and sulphate of potash, 

 which are perfectly soluble and the potassium readily available 

 to plants. The rate of application of either of these varies for 

 different uses from twenty-five to two hundred pounds per acre. 



. 45. Fertilized and unfertilized garden crops 



The crops at the right were fertilized, those at the left were not. (Photograph from 

 Rhode Island Agricultural College) 



130. Mixed fertilizers. Large quantities of fertilizer are 

 placed on the market as " mixed" fertilizers. When fertilizers 

 contain nitrogen, phosphorus, and potassium, they are known 

 as "complete" fertilizers. It is common to sell fertilizers of 

 this sort under such names as " grain growers," " potato ferti- 

 lizers," "lawn fertilizers," and "wheat growers." As a rule, 

 the proportions of the elements contained in such fertilizers are 

 planned in an attempt to bring the largest money return from 

 these respective crops when grown on poor soils (Fig. 45). 

 Fertilizers are also often sold under trade names, such as 

 "Anchor Brand," "Ox Brand," or "Western Brand." Since 

 it is impossible for the same fertilizer to be best for all soils, 

 and since farmers often do not know the needs of their soils, 



