TILLAGE 151 



done with a spade. In this operation a layer of soil the width 

 and depth of the spade is removed, forming a trench, and the 

 soil in the bottom of this trench is loosened by spading. Then 

 the trench is filled by the soil from a new trench adjoining it, 

 and so the work continues until the last trench is reached, 

 when the first soil thrown out is used to fill it. The subsoil is 

 often loosened by the explosion of small charges of dynamite. 

 In the home garden the spading fork is to be preferred to the 



Photograph by II. L. Ilollister Land Co. 



FIG. 108. Plowing with a tractor 



On the larger farms in the West a tractor is often used. With this it is possible 

 to plow a dozen or more furrows at once 



spade, since it breaks up the soil more thoroughly and is more 

 easily thrust into stony soil. After plowing or spading, the 

 harrow and rake are used to further pulverize the soil. The 

 more thoroughly this work is done, the better will be the seed 

 bed. Care must be taken not to work the soil when it is either 

 too wet or too dry, otherwise the soil crumbs will be broken 

 up and the soil puddled. A puddled soil is almost imper- 

 meable to air, water, and the roots of plants. Where an old 

 road or path across a field has been plowed up, the effects of 



