116 SCHOOL AND HOME GARDENING 



may be used in taking the temperature of the soil out of doors. A 

 suitable use for this exercise would be in the early spring before 

 planting seeds. Dig a hole with a spade as in taking soil samples. 

 With a wooden peg or lead-pencil make a hole in one side of the 

 hole made with the spade. The peg hole may be at any desired depth. 

 Insert the bulb of the thermometer in this peg hole and with the 

 fingers press the soil around tlie stem of the thermometer to exclude 

 air. After waiting one minute, read the temperature before removing 

 the thermometer from it's position. It is well to take the temperature 

 at a depth of three inches, six Inches, and nine inches. The tem- 

 perature of the air should also be taken. 



Soils are warmed by the admission of warm air to them 

 tlirough the f)rocess of ventilation. In the springtime the air 

 is usually warmer than the soil, and the soil is then usually 

 colder at the greatest depth, because the warm air has not yet 

 reached it enough. 



Such seeds as radish, lettuce, peas, and the small field 

 grains sprout readily in soil ranging in temperature from 

 50° to 70°. Corn, beans, cotton and beets sprout better 

 in soils at a temperature of 70° to 80°. 



7. Color and Temperature of Soils. — Fill two cans or two 

 deep boxes with the same kind of soil, both moistened and packed 

 alike. Cover one with a layer of very black soil or with soot from 

 the stove. Cover the other with a layer of chalk dust or other 

 white powder. Place these in a sunny window so the sun will strike 

 them alike. After a few hours, insert the bulb of the thermometer 

 in a hole made a few inches deep, with a peg or pencil, and read 

 the temperature of each with the thermometer in place. If the experi- 

 ment has been successful, the light-colored soil will remain cooler than 

 the black one. 



The experiment indicates that if color were the onlv 

 difference between soils, the light soils would be cooler. Light- 

 colored sand would be cooler than the heavy clay or black 

 loam or humus soils. Observation and temperature tests 

 prove the very reverse to be true. The effect of color is more 

 than overbalanced by the porous character of tlic sandy soils 

 which admit air readily, and warm air warms soils more 

 readily than tlie hot rays of the sun. 



