61 
SOIL TEMPERATURES OBSERVED AT AUBURN, ALA. 
As an illustration of soil temperatures in a southern locality I 
have chosen the following record for 1889 at Auburn, Ala., where 
the agricultural experiment station has maintained three sets of 
buried thermometers, two of them in sandy soils on hills and one in 
moist bottom land near the banks of a small stream. It appears 
from these records that the difference in temperature in the growing 
season between the so-called “cold wet” and “warm dry” soils 
averages but a few degrees; in fact, I doubt whether it is appreciable 
from observations having the accuracy of those here given. Thus 
at 3 inches depth and during the warm half of the year the maxi- 
mum temperatures on the hill average 1° FI. above those in the 
bottom land, while the minimum temperatures on the hill average 
2° F. colder than those of the bottom lands. The temperatures here 
given are the averages of the maxima and minima and are taken 
from successive monthly reports and from Bulletin No. 18 of the 
Alabama Agricultural Experiment Station. In these, as at most 
other United States stations, the correction for the temperature of 
the long stem of the thermometer still remains to be applied. A com- 
parison of the temperature at 3 inches depth with the maximum 
and minimum air temperature shows that the soil is warmer than 
the air in the daytime from April to October, inclusive, and 
warmer than the air at the minimum temperatures throughout the 
year. This latter is true for the minimum temperatures of the soil 
down to a depth of 96 inches, but the excess of maxima temperatures 
of the soil over those of the air during the daytime in summer 
ceases a little below 6 inches. Evidently the temperature of the soil 
is sufficiently- high to allow of the growth of some form of vegeta- 
tion throughout the year. 
Latremes and means of soil temperatures for 1889, as observed at Auburn, Ala. 
[Lat. 32°.6 N.; long. 85°.4 W.; altitude, 732 feet. ] 
| | 
Jan.| Feb.) Mar. Apr. May. June. July.) Aug.|Sept.| Oct. | Nov.| Dec. 
te 
| 
| | 
Mean air temperature___| 46.9 | 46.3 | 54.7 | 62.5 70.1 
| | | 
Air temperatures. of. |op.ijom log lop | ofp jop lop lop lor. 
Mean radiation temper- | | 
BGEUTOt = See eee SS 22 39.7 | 36.8 | 43.2 | 55.6 | 57.2 | 65.8 | 70.0 | 67.5 | 65.2 | 49.5 | 42.9 | 45.5 
Maximum air tempera- | | ea} | 
ING:) el a ee 5 ee 67.0 | 75.0 | 76.0 | 82.0 89.0 | 91.5 | 98.0 | 92.5 | 93.0 | 82.0 | 76.0 74.0 
Minimum air tempera- | | | 
DUS ae Se SD Se oe 20.0 | 16.5 | 30.0 | 38.0 | 45.0 | 46.0 | 67.5 | 68.0 48.0 | 38.0 | 24.0 29.0 
Maximum terrestrialra- | | 
diation temperature __| 51.0 | 66.5 | 54.0 | 62.0 63.0 | 74.0 | 73.5 | 72.5 | 78.0 | 60.0 | 60.0 | 59.5 
Minimum terrestrial ra- | | 
diation temperature __| 21.0 | 24.0 | 32.0 | 37.0 | 43.0 | 43.0 | 60.0 | 62.0 | 48.0 | 36.0 | 22.0) 30.5 
