734 STATE BOARD OF AGRICULTURE. 



(2) Signs of rise of temperature began to be manifested by March It 

 but the real ascent did not commence until March 25. The temperature 

 of the sand, gravel, loam and clay at the 6-inch depth rose almost simul- 

 taneously to about 40°F; that of the peat at the corresponding depth 

 did not reach this point until March 31 or 6 days later. From this date 

 on the average temperature of all the various soils tended to be equal. 

 During the month of April it varied only about 1 or 2°F as a monthly 

 average but as high as 7 or 8°F on certain individual days when the 

 air temperature underwent rapid changes. During the months of May, 

 June, July, August, September, October, and November, indeed up to the 

 next cycle, the average temperature of all these distinct classes of soil 

 was almost exactly the same. As a monthly average, the highest varia- 

 tion that occurred between any of them was only a little over 1°F. The 

 peat especially at the 6-inch depth had a slightly higher temperature dur- 

 ing the warmest part of the year than the other soils. The daily highest 

 average temperature was attained on June 10. The magnitude on this 

 date was as follows for the 6, 12 and 18-inch depths, respectively: 

 gravel 81.90°, 76.50°, 73.93°; sand 81.47°. 75.00°, 70.97°; loam 80.93°, 

 74.23°, 67.97°; clay 80.47°, 73.77°, 70.07°; and, peat 81.03°, 72.27°, 

 67.20F. The monthly highest average temperature, however was reached 

 in July with the following magnitudes: gravel 75.92°, 74.08°, 72.62°; 

 sand 75.24°, 73.30°, 71.53°; loam 75.80°, 73.27°, 70.15°; clay 75.31°, 

 72.27°, 71.26°; and, peat 76.93°, 74.06°, 71.74°F for the 6, 12, and 18- 

 inch depths, respectively. 



The results of the spring and summer months of the third year, there- 

 fore agree almost perfectly with those of the first year, but disagree with 

 those of the second year. As already seen in the second year the average 

 temperature of the different soils varied appreciably during the spring 

 and summer months, with the sand and gravel having the highest tem- 

 perature followed by loam, c\aj and peat, respectively. 



During the first and third year, however, all the diverse classes of soil 

 were covered with a thin layer of sand, as already stated, while during 

 the second year this cover of sand was not present and consequently the 

 natural surface of these soils was exposed to the atmosphere. 



The remarkable equality of temperature, therfore, of the various types 

 of soil during the first and third year when their surface was covered 

 with a thin layer of sand and its inequality during the second year 

 when their surface was not covered suggest the noteworthy fact that it 

 is the thin layer of sand that caused the equality. It accomplished this 

 mainly by equalizing to a greater or less extent the amount of water 

 that the various soils lost through evaporation. The clay, loam, and peat 

 and especially the latter, for instance, possessing a high water content 

 tended to lose more water through evaporation than the sand and gravel 

 whose water content is low, and consequently their temperature was kept 

 lower, just as the results of the second year show. By placing a thin 

 layer of sand, which acted as a mulch, over these types of soil whose 

 water content is high, the evaporation of their moisture was reduced, 

 and their temperature was thereby raised to the same magnitude as that 

 of the soils with a low water content. It was the inequality in the 

 amount of evaporation, therefore, that caused the various types of soil 

 to have different degrees of temperature; and when this difference in 



