170 



SOILS AND MANUEES 



WEIGHT AND AVERAGE COMPOSITION OF FARM CROPS, IN LBS. PER ACRE 

 continued. 



The total quantity of nitrogen, phosphoric acid and 

 potash contained in the crops of an ordinary four- course 

 rotation may be estimated approximately as follows : 



These figures do not include the ingredients contained 

 in the stubble and root portions of the hay and corn crops 



