34 SOILS AND PLANT LIFE 



22. How the Color of a Soil afiects its Temperature. — 

 It is a peculiar fact that dark colored things absorb more 

 of the sun's heat than do those which are light colored. 

 That this is true of soils is shown by the following experi- 

 ment: 



EXERCISE 14 



Object. — To determine the influence of the color of a 

 soil upon its temperature. 



Procedure. — Fill two cans to within an inch of the top 

 with any soil you may choose. Fill the remainder of one 

 can with some white powder, as slaked lime or chalk dust, 

 the other with coal dust or soot. Thrust the bulb of a 

 thermometer into each can to a depth of about an inch. 

 Record the temperatures one hour after the two cans have 

 been placed in the sunlight. 



Conclusions. — White reflects light, black absorbs it ; 

 and when light is absorbed, it is converted into heat. 

 Is not a dark suit or dress warmer in the summer than a 

 white one? Why? Should a Ught colored horse stand 

 more heat in the simimer time, other things being equal, 

 than a black one? Why? If time permits, compare the 

 temperatures of light and dark colored soils in the fields. 

 Are the fields to which green or barnyard manure was 

 added a year or two ago darker in color than those to 

 which none was added? Are the fields which were in 

 clover or pasture last year darker than those which have 

 been continuously cultivated? 



Name four ways by which a farmer may make the soil 

 of his fields warmer. 



23. The Advantages of a Warm Soil. — Seeds awaken, 

 or germinate, much more readily in a warm soil than in a 

 cold one. The growing plant also thrives better where 

 the soil temperature is favorable. The bacteria and 



