34 FARM ARITHMETIC. 



2. How many pounds each of nitrogen, phosphoric 

 acid and potash are removed from the farm when a ton 

 of butter is sold? 



3. How much butter was sold from your place last 

 year, and how many pounds or ounces of the elements 

 of plant food were contained in it? 



4. If a farmer sells 20 hogs averaging 150 pounds 

 each, how many pounds of nitrogen are taken away with 

 them? How many pounds of phosphoric acid? Of 

 potash ? 



5. How many hogs were killed on your farm last 

 year, or sold from it, and what was the total weight of 

 nitrogen in all of them together? Of phosphoric acid? 

 Of potash? 



ANSWERS TO ABOVE QUESTIONS. 



1. In one pound of butter there is 0.02 of an ounce of 

 nitrogen, 0.03 of an ounce of phosphoric acid, 0.005 of 

 an ounce of potash. 



2. In one ton of butter there are removed of nitrogen, 

 2.5 pounds; of phosphoric acid, 3.75 pounds; of potash, 

 0.6 pounds. 



4. With the 20 hogs are sold of nitrogen 60 pounds, 

 of phosphoric acid 244 pounds, of potash 4.7 pounds. 



The answers to these questions show how much less 

 loss in fertility there is when the corn, or at least a 

 part of it, raised on the farm, is fed to animals at home. 

 If the grain is all sold the needed elements of plant 

 food must, of course, be bought in the form of com- 

 mercial fertilizer. Let us see how much this amounts to 

 in dollars and cents. 



The cost of the three principal elements of plant food 

 varies considerably because there is such a large number 



