CHAPTER VII 



FIG. 41. 



PHOSPHATE FERTILIZERS 



225. Importance of Phos- 

 phorus as Plant Food. - 



Phosphorus in the form of 

 phosphates is one of the 

 essential elements of plant 

 food. None of the higher 

 orders of plants can complete 

 their growth unless supplied 

 with this element. The il- 

 lustration (Fig. 41) shows an 

 oat plant which received no 

 phosphorus compounds, but 

 was supplied with all the 

 other elements of plant food. 

 As soon as the phosphoric 

 acid stored up in the seed 

 had been utilized, the plant 

 ceased to grow, and after a 

 few weeks, died of phosphate 

 starvation, having made the 

 total growth shown in the 

 illustration. All crops de- 

 mand their phosphorus com- 



Oat Plant grown without pounds at an early stage o f 



development. Wheat takes 

 198 



Phosphates. 



