FEEDING THE PLANT 



99 



which makes its most rapid growth during the summer 

 season, June, July and August. The conditions are 

 not favorable in the early spring months for the change 

 of organic nitrogenous matter in the soil into nitrates, 

 whereas during the hot summer months the conditions 

 are extremely favorable for the change. 



Hence, upon soils containing a reasonable amount 

 of vegetable matter, the application of nitrogen to 

 wheat and grass might result in a very large increase, 

 whereas its application to a corn crop might not be 



n 



ZSi 



39SSSS 'i^^mmtm 



Fig 27— Corn Crib on Scales 



At Iowa experiment station 



followed by a considerable increase, because in the first 

 case the conditions make it needful that the crop shall 

 have an abundance of nitrogen, and in the second case 

 the conditions favor the change of the nitrogen already 

 in the soil into an available form. So it is that on the 

 same soil, one crop might be benefited by the applica- 

 tion of nitrogen, while for another the application of 

 nitrogen would not be likely to cause a profitable in- 

 crease in yield. The crop grown, too, and its period 

 of growth, determine to some extent the form, as well 

 as the kind, .of element that should be applied. 



