CHAPTER IX 



THE POTENTIAL PLANT FOOD: ITS STORES AND 

 NATURE 



Just as soon as it was determined that a mere chemical 

 analysis of the soil would not reveal the element or ele- 

 ments lacking therein, a study of the way in which dif- 

 ferent crops used the food elements was undertaken. 



A CROP THAT CALLS FOR MUCH NITROGEN 



Corn makes heavy demands on the nitrogen stores and does best when in 

 rotation with the legumes 



This study soon showed that all plants used the same 

 kinds of food, incorporating these foods in their body 

 tissues, and, also, that these foods were used by the 

 different plants in varying proportions: some using a 



