1919-20.] Effect of Weather Changes on Soil Temperatures. 65 
in spring; moreover, while warm spring rains percolate very rapidly 
into sand or loam and so carry their warmth with them, clay absorbs 
water so slowly that a large proportion of the water runs off down 
furrows, etc., and the residue takes so long to percolate that its heating 
effect is lost. 
Table VI.— Rise of Underground Temperature in Sand, Loam, and Clay. 
Sand. 
Loam. 
-■ 
Clay. 
Date. 
Number of 
Previous 
Dry Days. 
R 
Surface 
4-inch 
R*. 
R 0 
Surface 
4-inch 
R*. 
R 0 
Surface 
4-inch 
R 0 
Range. 
Range. 
Range. 
Range. 
Range. 
Range. 
1919. 
May 18 
0 
•60 
19-0° C. 
11-4° C. 
•43 
18-0° C. 
7*8° C. 
•40 
16*0° C. 
6-4° C. 
„ 19 
1 
•52 
26-0° C. 
13-5° C. 
•40 
24-0° C. 
9-6° C. 
•40 
17 0° C. 
6 8° C. 
„ 22 
4 
•40 
25-0° C. 
10 0° C. 
•35 
24-0° C. 
8-4° C. 
•39 
17*0° C. 
6-6° C. 
„ 26 
8 
•30 
28*0° C. 
8-4° C. 
•30 
27*0° C. 
8T° C. 
•38 
19-0° C. 
7-2° C. 
„ 28 
10 
•27 
29-0° C. 
7-8° C. 
•29 
28-0° C. 
8T° C. 
•37 
20-0° C. 
7-4° C. 
June 2 
15 
•23 
26-0° C. 
6-0° C. 
•28 
25-4° C. 
7T° C. 
•37 
18-0° C. 
6-7° C. 
May 18-28. Rise of 4-inch depth temperature : — 
Sand +8-2° C. Loam +6*6° C. Clay +4*2° C. 
Clay soil is thus cold and late in spring compared to the others, and, 
conversely, warm in autumn after the other two have cooled down by 
radiation and percolation of cold rains. 
The following figures for the difference in soil temperature at a depth 
of 6 inches in a sandy loam and clay soil, only about 200 yards distant 
from each other, are given in Science and Fruit Farming , by the Duke of 
Bedford and Spencer Pickering ' * 
Sandy Loam. 
Clay. 
January 
+ 0-9° F. 
February . 
+ 0*8° F. 
March 
+ 0-7° F. 
April .... 
+ 0-2° F. 
May .... 
+ 0-8° F. 
June .... 
+ 1-2° F. 
Mean of 20 years 
July .... 
+ 1*2° F. 
* 1895-1915. 
August 
+ 0*3° F. 
September . 
+ 0’0° F. 
+ 0 : 0° F. 
October 
+ 0-7° F. 
November . 
+ 1-0° F. 
December . 
+ 1-2° F. 
* Science and Fruit Farming , by the Duke of Bedford and Spencer Pickering. Macmillan. 
VOL. XL. " 5 
