180 



FOOD FOR PLANTS 



Percentage of Nitrogen Recovered in the Crops. 



Reference has already been made to the method 

 of calculating the percentage of nitrogen that is re- 

 covered in the crop. The recoveries for the four 



TABLE 2 



Percentage of Nitrogen Recovered from Different 

 Materials. 



different treatments covering the 20 years are 



shown in table 2. The averages for the period are as 

 follows : 



4B 32.69 per cent, (manure) 



8B 62.42 per cent. (Nitrate of Soda) 



17B 47.48 per cent, (ammonium sulfate) 



18B 48.69 per cent, (dried blood) 



This means that of 100 pounds of nitrogen applied 

 in the four different forms approximately one-third, 

 three-fifths, one-half, and two-fifths, respectively, are 



* First ten years, 

 t Second ten years. 

 i Twenty years. 



