118 ■ The Potato 



age, ground bone and sulphate of ammonia that drill well. 

 The cost of home mixing may be one dollar a ton, more or 

 less, sometimes under fifty cents. A tight wagon box or 

 barn floor, screen, measure and shovel are the only belong- 

 ings needed if enough is mixed so that batches are made 

 up of one or more bags of each material. If less, scales 

 are needed. Dealers do not like to sell materials in small 

 quantities, but by clubbing together farmers can buy car- 

 load lots. 



Most of the phosphoric acid in factory-mixed fertilizers 

 comes from acid phosphate. The value is the same from 

 any source if acid treated. If not so treated, as in tankage 

 or ground bone, it is slower to become available. Most of 

 the potash comes from muriate and kainit, which differ but 

 little in their action ; some comes from sulphate. Fertil- 

 izers vary mostly in the value of the nitrogen. The higher- 

 grade factory-mixed fertilizers are more certain to have 

 high-grade nitrogen than the low-grade cheaper mixtures. 



Before the great European war, the prices of fertilizers 

 had remained fairly constant for a number of years. The 

 experiment stations in the northeastern states usually 

 value the best grades of nitrogen at 15 to 18 cents a pound, 

 soluble phosphoric acid in acid phosphate and potash in 

 muriate at about 5 cents. These prices are ton lots of 

 the best materials bought for cash in large markets. 

 Buyers of car-lots usually purchase enough cheaper to 

 cover the cost of freight to country points at these prices. 



Lack of knowledge of fertilizers among farmers has led 

 to a failure to appreciate the fact that it is the cost a pound 

 of the plant-food which the fertilizer contains and its 

 quality that determines the actual value of any fertilizer, 

 not the price a ton. Many farmers look too often at 

 the cheapest, regardless of the analysis. For example, 



