TEMPERATURE 



303 



to 72 hours sooner in the part of the tray covered with dark soil. 

 The table following gives the temperature in the two parts of 

 the tray : 



Effect of Color on Soil Temperature " 



Flo. 134. Difference in growth on light and dark colored soils. A. corn , H. wheat ; C, water- 

 melon. 



The time and the number of plants mining through the soil 

 are governed to some extent by the color of the soil, as is shown in 

 the following table. 



