200 SOILS AND FERTILIZERS 



270. Inspection of Fertilizers. In many states 

 laws have been enacted regulating the manufacture 

 and sale of commercial fertilizers, and provision is 

 made for inspection and analysis of all brands offered 

 for sale. The label on the fertilizer package must 

 specify the percentage amounts of available nitrogen, 

 phosphoric acid and potash. Inspection has been 

 found necessary in order to protect the farmer and the 

 honest manufacturer. As the result of inspection and 

 analysis occasionally a fraud is revealed like the fol- 

 lowing : 7I 



Natural plant food, $25 to $28 per ton. 

 Composition. Per cent. 



Total phosphoric acid 22.21 



Insoluble " " 20.81 



Available " " 1.40 



Potash soluble in water. 0.13 



Actual value per ton, $1.52. . 



271. Mechanical Condition of Fertilizers. When 

 a fertilizer is purchased, its mechanical condition 

 should be considered. The finer the fertilizer, as a 

 rule, the better it is for promoting crop growth. 

 Some combinations of plant food produce fertili- 

 zers which become so hard and lumpy that it is diffi- 

 cult to crush the lumps before spreading. The 

 mass must be pulverized so that it may be evenly dis- 

 tributed, otherwise the plant food will not be econom- 

 ically used. A fertilizer that passes through a sieve 

 with holes 0.25 mm. in diameter is more valuable and 

 can be used to better advantage than one of the same 

 composition with particles 0.5 mm. in size. 



272. Forms of Nitrogen in Commercial Fertilizers, 



