FIRST STEPS TOWARDS AFFORESTATION 23 



to make explanation more simple the top half will be 

 considered as vegetable soil and the bottom half as subsoil. 



The subsoil, which usually contains little or no humus, is 

 then taken out and harrowed to the opposite end. This 

 leaves an open trench, say 20 inches deep. 



Another strip 18 inches wide is marked off, and the 

 top soil is again harrowed away and placed with that from 

 the previous strip. The shape of the trench will then be 

 similar to Fig. 3. 



Fig. 3.— Sketch of Trench. 



The subsoil from A is dug over into B, and the top soil 

 from the next strip at C is transferred to D on the top 

 of the subsoil at B. This is continued until the end of the 

 bed is reached, when the subsoil brought from the first 

 trench is put in to replace that removed from A and the 

 harrowed top soil used to fiU up D and E. If there is 

 turf to be disposed of, it should be chopped up finely with 

 a spade and placed between the subsoil and the top soil, 

 where it will rot and so enrich the soil. 



In trenching, aU large stones must be taken out and 

 any irregularities in the surface of the bed made level. 



The absence of large stones makes subsequent opera- 



