MECHANICAL DIVISION OP SOILS. 91 



winds, the light soluble manures are exhaled or washed out, 

 and they receive little compensation for this waste, in any 

 corresponding fertility they derive from the atmosphere in 

 return. To insure flat plowing on an old sward, the depth 

 of the furrow should be about one half its width, and the 

 lands or ridges, should be made as wide as possible. This will 

 give more evenness and uniformity of surface, and is an object 

 of importance, where it is to be again laid down as a meadow. 

 Some prefer for this purpose, to use the shifting mold-board, 

 side-hill or swivel plow, by all of which names it is 

 known. This can throw the furrow always in the same di- 

 rection, and is a right or left hand plow as may be required. 



Depth of Plowing. All cultivated plants are benefitted 

 by a deep, permeable soil, through which their roots can 

 penetrate in search of food ; and although depth of soil is not 

 fully equivalent to its superficial extension, it is evident, that 

 there must be a great increase of product from this cause. 

 For general tillage crops, the depth of soil may be gradually 

 augmented to about twelve inches, with decided advantage. 

 Such as are appropriated to gardens and horticultural pur- 

 poses, may be deepened fifteen, and even eighteen inches, to 

 the manifest profit of their occupants. But whatever is the 

 depth of the soil, the plow ought to turn up the entire mass, 

 if within its reach ; and what is beyond it, should be thorough- 

 ly broken up by the subsoil plow, and some of it occasional- 

 ly incorporated with that upon the surface. 



The subsoil ought not to be brought out of its bed, except 

 in smalt quantities. It should then be exposed to the atmos- 

 phere during the fall, winter and spring, or in a summer fal- 

 low ; after which, and as a necessary preparation for a crop, 

 it should receive such manures as are necessary to put it 

 at once into a productive condition. The depth of the soil 

 can alone determine the depth which the plow should work ; 

 and when the former is too shallow, the gradual deepening 

 of it should be sought, by the use of proper materials for im- 

 provement, till the object is fully attained. Two indifferent 

 soils of opposite characters, as of a stiff clay and sliding sand, 

 sometimes occupy the relation of surface and subsoil towards 

 each other ; and when intimately mixed, as they may fre- 

 quently be by deep plowing alone, and then subjected to the 

 meliorating influence of cultivation, they will frequently 

 produce a soil of great value. 



Cross plowing is seldom necessary, except to break up 

 tough sward or tenacious soils, and the former is more ef- 



