40 T. Lyttleton Lyon and James A. Bizzell 



and the protein nitrogen content of the crop on certain dates, the amounts 

 of nitrogen removed by the plants on these dates may be calculated; 

 and on the basis of weights and analysis at final harvest, the proportion 

 of the total nitrogen acquired by the plant may be deduced for any of 

 the dates on which the cuttings were made. Estimated in this way 

 the maize plants had absorbed 43 per cent of their nitrogen on July 24 

 and 63 per cent on August 8. In 1889 the maize was planted on May 12 

 and was mature by September 24. It had acquired 53 per cent of its 

 total nitrogen on August 2, 50 per cent on August 17, and 67 per cent 

 on August 31. The figures for 1889 are somewhat contradictory, as the 

 proportion of nitrogen taken up on August 17 was less than that on 

 August 2. The figures, as a whole, indicate that at least 50 per cent of 

 the nitrogen utilized by Pride of the North maize in this locality in an 

 average year is absorbed by the end of July. Referring to Table 3, it 

 will be seen that on July 27 the nitrate content of the soil under maize on 

 the unfertilized plats was 194 parts per million, while that on the culti- 

 vated soil on which no plants grew was 181 parts per million. Even as 

 late as August 10 the nitrate content under the maize on these plats was 

 181 parts per million, and on the unplanted soil it was 191 parts per million. 

 It is to be expected that there would be a large accumulation of nitrates 

 in the cultivated and uncropped soil, but why this should be true of the 

 soil carrying a heavy crop of maize, practically one half of the nitrogen 

 of which had been absorbed, it is difficult to understand. The formation 

 of nitrates during this period must have proceeded with tremendous 

 activity if nitrates were the source of nitrogen supply for the crop. 



Some conditions indicate that maize, at least during part of its period 

 of growth, utilizes nitrogen rather largely in forms other than as nitrates. 

 Ammoniiication apparently never proceeds more rapidly than nitrifi- 

 cation in this soil, which would bar that form of nitrogen as a very con- 

 siderable source of suppl3^ Organic nitrogen in some of its soluble forms 

 is the only remaining alternative. The great benefit derived by maize 

 from the application of farm manure suggests the possible use of nitrogen 

 in this form. 



During the later growth of the maize plant there is a large falling-off 

 in the nitrate content of the soil under the plants as compared with that 

 in the unplanted soil. This indicates either that nitrates are absorbed 

 by maize in large quantities during the period of growth in which it is 



