Relations of Higher Plants to the Formation of Nitrates 49 



TABLE 17 (concluded) 



Average of first and second eight inches (continued) 



Plat 



Crop 



o 



IM 



O 



d 



D. 

 < 







o 

 o 



3 



O 



o 



>. 

 3 



1-5 



■* 



3 

 M 



< 



O 



CO 



3 

 M 

 3 



00 



u 



< 



2 



.a o 



c -g 



So 



0. 



o fe 



u 



o 



2206, 2214 \ 

 2406, 2414 / 



2206, 2214 \ 



2406, 2414 / 



2207, 2215 1 



2407, 2415 / 



2207, 2215 \ 



2407, 2415 / 



2208, 2216 \ 



2408, 2416 / 

 2208, 2216 \ 

 2408, 2416 / 



Potatoes 



29 

 27 

 21 



28 

 22 

 26 



22 

 27 



3 

 19 



3 

 19 



44 

 76 



6 

 40 



3 

 38 



27 



73 



6 



48 



4 



47 



29 

 84 



9 

 50 



8 

 43 



47 

 132 

 19 

 83 

 16 

 110 



49 

 102 

 20 

 74 

 12 

 70 



39 

 120 



Oats 



21 





96 



Oats, followed by maize 



17 

 75 







A study of the nitrates as recorded in Table 17 shows that the maize, 

 potatoes, and oats bear about the same comparative relation to the nitrate 

 content of the soil that they did in previous years. This characteristic 

 relationship between the crop and the nitrate content of the soil holds 

 also, with some variation due to the season, for the different stages of 

 growth of the plants. 



In the first eight inches there is no tendency for the nitrates under the 

 cultivated maize to run higher, at certain periods of growth, than the 

 nitrates in the unplanted soil; but under the maize on the scraped and the 

 late-planted plats the nitrates are higher during a part of the growing 

 season than in the unplanted sections of these plats. In the second eight 

 inches this is also the case. 



The effect of all crops, and especially of oats, in depressing the nitrate 

 content during the later stages of growth and afterwards is very marked, 

 even when the nitrates in the unplanted soil continue to increase late 

 into the autumn. 



The maize that was harvested on August 1 did not reduce the nitrate 

 content of the soil to the same extent after that date as did the maize 

 not harvested at that time, but there was no tendency for the nitrates 

 under the crop to increase relatively to the nitrates in the bare soil. This 

 may mean that the maize plant uses a considerable quantity of nitrate 



