SOIL TEMPERATURES AS INFLUENCED BY CULTURAL 

 METHODS 



By Joseph Osk.^mp, 

 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 1 2 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 Q inches of soil on the experimental plots ^ 



o These analyses were made by the Bureau of Soils, United States Department of Agriculture. 



Journal of Agricultural Research, 

 Dept. of Agriculture, Washington, D. C. 



5773°— 15- 



Vol. V, No. 4 

 Oct. 25, 1915 

 Ind.— I 



(173) 



