16 GENERAL ADVICE 



planted or built upon, or because suitable outlets 

 can not be found. In such cases, recourse is had 

 to very deep preparation of the land, either every 

 year or every two or three years. In small gar- 

 den areas, this deep preparation will ordinarily 

 be done by trenching with a spade. This opera- 

 tion of trenching consists in breaking up the earth 

 two spades deep. Fig. 6 explains the operation. 

 The section at the left shows a single spading, the 



7. Home-made subsoil plow. 



earth being thrown over to the right, leaving the. 

 subsoil exposed the whole width of the bed. The 

 section at the right shows a similar operation, so 

 far as the surface spading is concerned, but the 

 subsoil has also been cut as fast as it has been 

 exposed. This under soil is not thrown out upon 

 the surface, and usually it is not inverted; but a 

 spadeful is lifted and then allowed to drop so that 

 it is thoroughly broken and pulverized in the 

 manipulation. In all lands which have a hard 



