EXPERIMENT STATION BULLETINS. 



729 



The daily and monthly average temperature of the second year, Decem- 

 ber 1, 1912 to November 30, 1913, are contained in Tables 1 to 12, in- 

 clusive. Beginning with the data of the month of December it will 

 readily be seen that at the commencement of the month all the various 

 types of soil at the three different depths had practically the same magni- 

 tude of temperature and had not yet reached the freezing point. The 

 temperature at all three depths in every soil diminished gradually until 

 December 12 when the upper 6-inch depth began to freeze. At this date 

 the 6-inch depth of only the sand and gravel froze, that of the loam and 

 clay froze one day later and peat ten days later. It will be noted, how- 

 ever, that while the peat at the 6-inch depth froze ten days later than 

 that of the other soils its temperature during this time was only a few- 

 tenths of a degree higher. The temperature at the 6-inch depth of all the 

 soils remained at or slightly below 32°F until January 3, when it rose in 

 all of them a few tenths of a degree but it fell again at or below 32°F on 

 January 29. Between February 4 and 14 the temperature at the 6-inch 

 depth of all soils was several degrees below zero and on February 13 

 reached its minimum for the winter. At this date the average tempera- 

 ture of the various soils at this upper depth was as follows : gravel 22.43°, 

 sand 19.60°, loam 23.30°, clay 23.93°, and peat 20.50°F. It is of great 

 interest, therefore, to note that all these diverse classes of soil had prac- 

 tically the same average temperature during this period of cold weather 

 in spite of their great difference in heat conductivity, water content, etc. 



