FERTILIZER PRACTICE 571 



are to be added, especially potatoes and garden crops, 

 it is desirable to drop only a portion of the fertilizer with 

 the seed, the remainder having been broadcasted by ma- 

 chinery and harrowed in earlier. 



479. Fertilizing crops. Three primary considerations 

 must be observed in the actual utilization of fertilizers: 

 (1) the percentage of nitrogen, phosphorus, and potash 

 suited to the crop and the soil ; (2) the availability of the 

 carriers; and (3) the amounts to be applied. It is evi- 

 dent, due to so many factors that are difficult to control, 

 that fertilizer formulas for different crops on particular 

 soils are difficult to determine. In fact, such data can 

 never be more than merely suggestive. Further, the 

 best quantity of a mixture to apply, even though it is 

 perfectly balanced, is a figure that can only be approxi- 

 mated. Probably the largest percentage of the fertilizer 

 waste that occurs annually can be charged to this factor. 

 Many farmers make the mistake of applying too much 

 fertilizer. As a consequence, any information along such 

 lines can only be suggestive, rather than literal, it being 

 understood that the general formulas suitable to various 

 crops, and the quantities ordinarily applied, are subject 

 to wide variations. 



The fact that there are so many mixtures on the market 

 in this country for the same crops would be rather amus- 

 ing, did it not so strikingly expose the ignorance of the 

 manufacturer as well as the gullibility of the public. 

 Recognizing the need of standard formulas subject to 

 change according to local conditions, Van Slyke 1 has 

 offered the following for general use : 



Slyke, L. L. Fertilizers and Crops, p. 528. New 

 York. 1912. 



