EXPERIMENT STATION BULLETINS. 807 



From an examination of the above table it will be seen that as a 

 monthly average the soils covered with snow had a higher temperature 

 than the bare. Indeed, the soil covered with the uncompacted snow and 

 layer of vegetation did not freeze and its temperature was about 7°F 

 higher than that of the bare, while the plots with the compacted and un- 

 compacted snow were about 2 and 4°F warmer, respectively. 



The daily records show that whenever the air temperature fell very low 

 that of the bare soil also would go down many degrees lower than that 

 of the other soils. Thus, for instance, on January 30, which was a cold 

 day the average temperature ranged as follows in the various plots : bare 

 16.27°, compacted 18.37°, uncompacted 27.90°, and uncompacted with 

 vegetation 32.60°F. While the minimum temperature for the same day 

 ran as follows: bare 7.5°, compacted 15.60°, uncompacted 27.0°, and un- 

 compacted with vegetation 32.2 °F. The influence, there f core, of snow 

 upon soil temperature in the winter is very great. 



EFFECT OF TOPOGRAPHIC POSITION ON SOIL TEMPERATURE. 



Considerable is already known concerning the effect of topographic 

 position on soil temperature. Since, however, it was resolved to in- 

 vestigate the general subject of soil temperature as systematically and 

 thoroughly as possible in order to arrive at definite and safe conclu- 

 sions, a study of this phase was also conducted. This part of the in- 

 vestigation consisted in making observations on soil temperature at 

 various topographic positions, namely, at a south slope, north slope, top 

 of a hill, at a river bank, and at a low land. All these points were lo- 

 cated within a small area. The river was situated between the north and 

 south slope. The altitude and angle of these slopes were of medium 

 magnitude. The altitude of the hill, which was the top of the north 

 slope was also comparatively small. The soil of the low land was muck, 

 that of the other locations was a sandy loam. The temperature was re- 

 corded three times a day, daily except Sunday, at 3 inches depth, by 

 means of soil mercury thermometers. The surface of all these soils was 

 kept free from vegetation. The data obtained from this series of ob- 

 servations are presented in Table 89. On account of limited space only 

 the monthly maximum, minimum, amplitude and average temperature 

 are given. 



