796 STATE BOARD OF AGRICULTURE. 



ture of the peat approached that of the other soils quite close so 

 that the difference was only about 1 or 2°F at both depths. From this 

 month on the various soils divided themselves into two distinct groups 

 as regards their temperature. The sand or untreated soil and the peat 

 maintained a low but almost equal temperature and the soils possessing 

 organic matter in percentages of 2.()S, ;i..32, 5.47, and <).!),") had a slightly 

 higher temperature hut also of practically equal magnitude. Thus, in 

 the month of July, when the highest average temperature was attained, 

 the various soils had the following degree of temperature at the 5 and 

 18-inch depths, respectivelv : 1.81% organic matter 77.01°, 7;iSf)°; 2.08% 

 78.47°, 75.16°; 3.32% 79.09°, 74.67°; 5.47% 79.17°, 74.01°; 6.95% 

 79.10°, 73.55°; and, peat 75.90°, 71.69°F. In this month the difference 

 in temperature between the sand and peat was greater than at any other 

 month during the summer and fall. The above division or order con- 

 tinued, with small variation, until October, and then the magnitude be- 

 came more or less equal in all the soils. From October until December, 

 the end of the year, all the soils had approximately the same average 

 temperature. 



The data for the third year or cycle are contained also in Table 83. 

 The results of this year reveal exactly the same principles as those of 

 the second year just discussed and consequently need no detailed con- 

 sideration. 



The results of the fourth year are represented at the bottom of Table 

 83. These records differ from those of the previous years in that they 

 were obtained at 3 and 6-inch depths instead of 5 and 18. Even then, 

 however, the order and behavior of the average temperature at these 

 upper depths agree with those of the lower depths of the preceding years 

 and consequently reveal practically the same principles. 



It should be noted that the average air temperature was Icwer than 

 that of all the soils at both depths every month in the year throughout 

 the three years. 



In the spring all the soils with the exception of peat, thawed at about 

 the same time; peat, however, thawed much later. 



Th's investigation goes to prove then that soils either with wLlte color 

 and low moisture content or with black color and high water content 

 have a lower average temperature during the spring and summer than 

 soils possessing these properties in medium proportion. In other words 

 the white color of a soil retlects so much of the sun's rays that it pre- 

 vents the soils from attaining a high temperature in spite of its low 

 .water content and small amount of evaporation, while the excess of 

 water content of a black soil, such as i^eat, consumes so much of the heat 

 energy in its evaporation process that it keeps the temperature of 

 the soil low in spite of its black color and hence its great heat absorbing 

 power. 



MONTHLY_, SEASONAL^ AND YEARLY MAXIMUM^ MINIMUM^, AND AMPLITUDE OV 



TEMPERATURE'. 



Next, the monthly, seasonal and yearly maximum, minimum and ampli- 

 tude of temperature of the foregoing various soils for the three years will 

 be considered. These data are shown in Tables 84, 85 and 86, inclusive. 



