T. Lyttleton Lyon and James A. Bizzell 





TABLE 8 {cont 



inued) 











Maize, 1908 





June 2 to 22 



June 23 to 

 July 6 



July 7 to 27 



July 28 to 

 August 10 



Plat 



711 



720 



711 



720 



711 



720 



711 



720 



Temperature (Fahrenheit) . . 

 Nitrates (parts per million) . . 



66.8° 

 40 



65.9° 

 31 



69.2° 

 62 



69.8° 

 102 



69.4° 

 182 



69.8° 

 211 



72.2° 

 162 



71.1° 

 136 



In the year 1907 the nitrates were fairly constant in amount through- 

 out the season in these plats, in spite of changes in soil temperature. 

 This is probably because of the heavy draft of the timothy crop on the 

 soil nitrates. In 1908 the nitrates increase in quantity up to July 27, 

 although the average temperature from July 6 to that date is practi- 

 cally constant. From July 28 to August 10 there is a marked rise in 

 temperature in both plats, but it is accompanied by a decrease in nitrates. 

 The temperatures reached in these plats are^not high enough to hpve any 

 depressing effect on nitrification, as has been demonstrated by many 

 experiments. 



In diagrams I (page 20), V (page 42), VI (page 52), and XVI (page 

 64) are shown the daily mean air temperatures, and in some seasons the 

 daily soil temperatures, and the nitrate contents of the soil for the years 

 1908, 1910, 1911, and 1912. In the unplanted soil the nitrates usually 

 increased in the spring with the rise in temperature. This continued 

 until July, after which there was apparently little relation between tem-- 

 perature and nitrate content until late autumn. For instance, in 1911 

 and 1912 there was a decrease in the temperatures from the first half 

 of July to the end of August, while the nitrate content of the unplanted 

 soil increased steadily during that period. The planted soil cannot be 

 said to show any consistent relation between temperature and nitrate 

 content during midsummer. 



Experiments with maize in which other plants were sown 

 In 1907 and 1908 certain plats were planted to maize, between the rows 

 of which the seeds of other plants were sown broadcast. A part of each 

 plat was not planted to maize, but when the other seed was sown between 



