MINERAL MATTER FOR CORN LAND 



139 



The fertilizer applied should be planned to supply the 

 needed element or elements, rather than all elements. 

 Also, a certain element may be deficient a part of the season 

 but more plentiful at some other period. This is true of 

 nitrogen, which is often deficient in early spring, especially 

 on heavy clay soils, but may be more abundant by mid- 

 summer. 



The Ohio Agricultural Experiment Station reports an 

 experiment in which fertilizers were applied in arbitrary 

 quantities in comparison with plats on which " the three 

 fertilizing elements, nitrogen, phosphorus, and potassium, 

 are given in approximately the same ratio to each other 

 in which they are found in the plant." ' 



TABLE XXVIII 



Fertilizer Tests with Continuous Corn Culture at the 

 Ohio Agricultural Experiment Station. Average for 

 Sixteen Years, 1894-1909 



The ratio between the elements in the two mixtures and 

 that required by the plant is shown in the following state- 

 ment : — 



1 Ohio Agr. Exp. Sta., Circ. No. 104 ■• 3. 1910. 



