72 



T. Lyttleton Lyon and James A. Bizzell 



Nitrates in the late-planted maize plats are shown in Diagram XXI. 

 Owing to the late planting — July 5 — the nitrates never fall very low and 

 are highest in August; this is another indication that the time of year is 

 not the controlling factor in the maximum nitrate content. Following the 

 harvest of this maize on August 20 there is a decrease in nitrates. 



The nitrates under potatoes are shown in Diagram XXII. As in pre- 



60 

 50 

 40 

 30 

 20 

 JO 



%L^NG ^UNE JULY 



AUGUST SEPT 



O 



DIAGRAM XXIII. 



Relative nitrate content of soil under oats, cultivated after 

 harvest, 1912 



vious years the maximum nitrate content occurs in July, and the ni- 

 trates decrease from that time until the close of the season. 



The oat plats, represented in diagrams XXIII and XXIV, show the 

 characteristic declme in nitrates, except m the plats on which maize was 

 planted after the oats were harvested. In these plats there was a slight 

 rise of nitrates in September; but, since the maize grew only five or six 

 inches high, the effect on the nitrates was unimportant. 



