90 



FARM ARITHMETIC. 



257. This soil was analyzed by a chemist who found 

 that it contained in the upper layer 0.162 per cent of nitro- 

 gen, 0.249 per cent of phosphoric acid and 0.386 per cent 

 of potash. How many pounds per acre of each of these 

 elements of fertility did this upper layer contain? 



258. This chemist also analyzed the second layer and 

 found 0.092 per cent of nitrogen, 0.134 per cent of phos- 

 phoric acid, and 0.224 per cent of potash. How many 

 pounds of each did this second layer contain ? 



GETTING HUMUS INTO THE SOIL. 



The rape crop seeded at the last cultivation of the corn is now being plowed 

 under to keep up the humus supply of the land. Cowpeas, rye and crimson 

 clover are other good crops to use for the same purpose. 



259. What was the number of pounds each of nitro- 

 gen, phosphoric acid, and potash per acre in the 12 inches 

 of soil? 



260. A crop of wheat which yields 30 bushels per acre 

 removes from the soil by chemical analysis, as indicated, 

 48 pounds of nitrogen, 21.1 pounds of phosphoric acid, 

 and 29.8 pounds of potash. When wheat yields at this 

 rate, how many crops will the nitrogen in this soil supply? 



