SAVING SOIL MOISTURE 



53 



the other. A little water was then added to the pan. 

 The water rose through the soil by capillary attraction at 

 about the same rate in both chimneys until it reached the 

 coarse soil in the left one. It continued to rise to the top 

 of the soil in the right-hand chimney, but was "held back 

 several hours by the coarse soil at the top of the left one. 

 Soil Mulch. This experiment shows that, if the surface 

 of the land is covered with an inch or two in depth of dry, 



Fig. 23. Effect of pulverizing soil. 



crumbled soil, the water will rise through this layer much 

 more slowly than through the soil below. Since evapora- 

 tion occurs almost entirely at the surface of the soil, 

 this crumbled layer greatly hinders evaporation, the water 

 thus being saved for growth. This crumbled layer, which 

 is called a soil mulch, is formed by passing over the ground 



