PLANT FEEDING. 



21 



pounds or 20 pounds in a ton. When a range is given in 

 guaranteed percentages make the calculations on the 

 lowest percentage, since in all probability that most 

 nearly represents the actual composition. By "money 

 value" is here meant the actual market cost of the plant 

 food elements in the fertilizer, not its real value as 

 based on the increased value of the crop due to its use. 

 This latter may be out of all proportion to the actual 

 cost of the fertilizer whether mixed at home or factory 

 made. This latter or real value will depend upon the 

 degree in which the percentages of the different food 

 elements are suited to the given soil and crop. 



WHEAT 



CORN 



OATS POTATOES DAIRY COTTON 



SEVEN OF OUR LEADING FARM PRODUCTS. 



When sold off the farm just so much plant food is sent away. The relative 

 proportions are shown above and apply to nitrogen, phosphorus and potassium 

 in a ton of each product. 



64. What is the money value of plant food in a fer- 

 tilizer containing 



Phosphoric acid 7 to 8 per cent, 

 Nitrogen 1.60 to 2 per cent, 

 Potash 2 to 2.75 per cent? 

 Commercial value, $30. 



Solution: When the percentages are multiplied by 20 we ob- 

 tain the number of pounds in a ton, and when this is multiplied 



