SOIL TEMPERATURES AS INFLUENCED BY CULTURAL 
METHODS 
By Joseph Oskamp, 
Research Assistant in Pomology , Purdue University Agricultural Experiment Station 
The data here reported were accumulated under natural field condi¬ 
tions during a period of two years on three plots in a young apple orchard, 
as follows: (i) Tillage with a cover crop, (2) straw mulch, and (3) grass 
land. The temperature effect of cultural methods is a detail of a general 
investigation of the phenomena of orchard soil management. The data 
have a bearing on other soil problems perhaps important enough to 
warrant separate presentation at this time. 
The temperatures were recorded automatically by means of soil ther¬ 
mographs manufactured by Julien P. Friez & Sons. This instrument 
consists of a cylinder revolved by an 8-day clock. Blank forms are 
placed on the cylinder and the temperatures are traced thereon by a pen 
connected with the thermometer bulb. Temperatures are thus recorded 
continuously. 
The thermometer bulbs were planted 5 or 6 feet northeast of each tree 
and at a depth of 9 inches. On the straw-mulch plot the bulb was placed 
under and 12 inches from the outer edge of the mulch collar. Only one 
instrument was used on each plot. It is felt, however, that the records 
are trustworthy and portray with reasonable exactness the existing condi¬ 
tions. All instruments were carefully checked with a standard ther¬ 
mometer at the beginning and during the course of the experiment, and 
their behavior was highly satisfactory. Great care was exercised in 
changing the chart sheets, to see that each blank was properly placed. 
The plots are located on a glaciated, rough, river-bluff, upland soil 
in southern Indiana. The rocks of the region are limestone, which out¬ 
crop on the steeper hillsides. The mechanical analysis shows the soil 
to be a clay silt. (See Table I.) 
Table I .—Mechanical analysis of upper g inches of soil on the experimental plots 
Plot. 
Fine gravel 
(2 to 1 mm.). 
Coarse sand 
(1 to 0.5 
mm.). 
Medium 
(0.5 to 0.25 
mm.). 
Fine sand 
(0.25 to 0.1 
mm.). 
Very fine 
sand (0.1 to 
0.05 mm.). 
Silt (0.05 to 
0.00s mm.). 
Clay 
(0.00s too 
mm.). 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
Per cent. 
A. 
0. I 
0.7 
0.8 
1.8 
82. I 
13. 0 
C. 
. 2 
.8 
•9 
1.4 
5*2 
78.7 
12. 5 
D. 
. 2 
•7 
.8 
1. 6 
7-3 
77.0 
12. 4 
a These analyses were made by the Bureau of Soils, United States Department of Agriculture. 
Journal of Agricultural Research, 
Dept, of Agriculture, Washington, D. C. 
ak 
5773°—15 - 3 
(173) 
Vol. V, No. 4 
Oct. 25, 1915 
Ind.—1 
