44 



T. Lyttleton Lyon and James A. Bizzell 



TABLE 15. 



Nitrates in Each Foot of the Upper Four Feet of Soil 

 (Parts per Million) 





Depth 



May 12 



July 28 



August 17 



September 9 



October 17 



Crop 



-d 





^ 





■a 





"0 





■o 



































7 





■a 





■o 





■o 





-0 







C3 





C3 



-S 



s 



S 



c3 



■g 



cS 









a 





P. 





a 





0. 





a 









a 



S 



a 



s 



a 



E 



a 



s 





S 



Maize 



1 



66 



67 



174 



92 



201 



167 



236 



273 



309 



167 



Maize 



2 



34 



25 



55 



47 



49 



43 



79 



100 



64 



57 



Maize 



3 



25 



17 



41 



26 



44 



34 



47 



56 



43 



33 



Maize 



4 



1 



21 



15 



44 



31 



42 



24 



45 



72 



50 



40 



Total 



146 



114 



314 



196 



336 



268 



407 



501 



466 



297 



Potatoes 



95 



34 



155 



145 



164 



135 



110 



130 



35 



145 



Potatoes 



2 



39 



19 



50 



44 



63 



49 



52 



60 



29 



42 



Potatoes 



3 



30 



20 



37 



35 



44 



38 



28 



38 



25 



38 





4 



1 



31 



18 



35 



31 



42 



36 



28 



29 



27 



37 







Total 



195 



91 



277 



255 



313 



258 



218 



257 



116 



262 



Oats 



97 



49 



106 



84 



96 



154 



84 



170 



153 



211 



Oats 



2 



32 



27 



37 



33 



39 



48 



28 



47 



51 



53 



Oats 



3 



16 



12 



21 



23 



28 



35 



20 



46 



27 



28 



Oats 



4 



31 



22 



22 



23 



25 



30 



22 



40 



28 



33 



Total 



176 



110 



186 



163 



188 



267 



154 



303 



259 



325 



foot, as would be the case if the augmented nitrate content of the surface 

 foot was due to an upward movement of the nitrates. On the other 

 hand, the surface and second feet usually increase or decrease in nitrates 

 on the same dates, indicating a downward movement of the nitrates. 

 It would appear from these figures that in the main the nitrate content 

 of the surface foot is determined by the rate of nitrification and by the 

 removal of the nitrates, by various means, from that layer of soil. 



The average nitrate content of the maize, potato, and oat plats for the 

 season bears no definite relation to the quantities of nitrogen removed 

 in the crops. In Table 16 the yield of dry matter and of nitrogen in the 

 crops and the average nitrate content of the soil are given. 



As usual, the nitrate content is highest under maize, next under pota- 

 toes, and lowest under oats. As the nitrogen removed from the soil by 

 the maize crop was less than that absorbed by either of the others, the 

 higher nitrate content of the soil might be considered to be due to that; 

 however, as the potatoes removed more nitrogen than the oats and yet 

 the nitrate content under the potatoes is higher than that under the 



