240 



ROCKS AND SOIL 



food and allows air to pass through the soil. By either 

 a loose surface mulch or by a paper mulch as seen below 

 water is more easily kept in the garden soil. 



Mulches. Farmers have learned by experience the 

 value of cultivating the surface of the ground to a depth 



of three or four 

 inches, making a so- 

 called dust mulch 

 over the surface. If 

 the surface becomes 

 hard and cracks, the 

 water will evaporate 

 very quickly. By 

 placing a finely pow- 

 dered layer of soil 

 over the top of the 

 field, water will be 

 held in it for a much 

 longer period. In 

 some parts of the 

 West where rain is 

 very infrequent, 

 farmers practice 

 what is known as 

 dry farming. To do 

 this they must first 

 plow the ground deep 

 so that when the rain comes the ground will be ready to 

 soak it up and retain it. Then the surface layer of the 

 ground must be constantly worked and turned over to 

 form a surface mulch. This is done by making a layer 

 of very finely pulverized soil on top. The latest method 

 of keeping water in the soil is seen in the picture. 

 Here a layer of heavy paper is placed over the soil in 

 which the plants are growing and this prevents the water 



U. S. Dept. of Agr. 



Paper mulch. Experiments have shown that 

 moisture is best kept in the ground by means of 

 a paper mulch such as is seen in this picture. 

 Are there any evidences of its use shown here ? 



