14 



Fl-KTILITV AND I'lvRTlLI/.l'K HINTS 



1. The available supply of plant food. 



2. The physical condition of the soil. 



3. The biological condition of the soil. 



I. The Plant Food Supply. — It may be surprising to know that 

 most farm soils, even those that produce poor crops, are abund- 

 antly supplied with plant food.* 



Chester of the Delaware Agricultural College, states:^ An 

 average of the results of 49 analyses of the typical soils of 

 the United States showed per acre for the first eight inches of 

 surface, 2,600 pounds of nitrogen, 4.800 pounds of phosphoric 

 acid and 13,400 pounds of potash. The average yield of wheat 

 in the United States is 14 bushels per acre. Such a crop will 



Plant Food Removed by Crops in Pounds Per Acre. 



Crop 



Wheat, 20 bu 



Straw 



Total 



Barley, 40 bu ■ • • ■ 

 Straw 



Total 



Oats, 50 bu 



Straw 



Total 



Corn, 65 bu 



Stalks 



Total 



Peas, 30 bu 



Straw 



Total 



Flax, 15 bu 



Straw 



Total 



Meadow hay . . . . 

 Red clover hay • • 

 Potatoes, 300 bu. 

 Mangels, 10 tons 



WeTght >^J'-S^" 



1,200 



2,OCO 



1,920 

 3.000 



1,600 

 3,000 



2,200 

 6,000 



1,800 

 3.500 



2,000 



4,oco 

 18,000 

 20,000 



25 



900 I 39 

 1,800 15 



Phosphoric p^^^^j^ 



12-5 



7-5 



9 



1-5 



9-5 



Bowker, Plant Food. 



Bui. 47, Minnesota Experiment Station. 



