MECHANICAL DIVISION OP SOILS. 79 



maintain^ it-- position \\ithout crumbling. The advantage of 

 ;i di \ surface and early working are equally secured by this 

 hit IT method ; and to prepare for planting, the furrows need 

 only to be split by running a plow through their centre, 

 when thoy are ready for the reception of the seed. 



PLOWING SANDY OR DRY SOILS. These require flat plow- 

 ing, which may he done when they are either quite wet or 

 dry, but never till wanted for use. By exposure to heat, 

 rains and atmospheric influences the light soluble manures 

 are exhaled or washed out, and they receive little compensa- 

 tion 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 land or ridges as wide as can conve- 

 niently be made, so as to preserve as much uniformity of 

 surface over the whole field as possible. 



DEPTH OF PLOWING. All cultivated plants are benefitted 

 by a deep permeable soil, through which their roots can 

 penetrate in search of food ; and a though 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 12 inches, with decided advantage. 

 Such as are appropriated to gardens and horticultural pur- 

 poses may be deepened to 15 and even 18 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 thor- 

 oughly broken up by the subsoil plow, and some of it occa- 

 sionally incorporated with that upon the surface. The sub- 

 soil ought not to be brought out of its bed except in small 

 quantities to be exposed to the atmosphere during the fall, 

 winter and spring, or in a summer fallow ; nor even then, 

 but with the application of such fertilizers as are necessary 

 to put it at once into a productive condition. The depth of 

 the soil can alone determine the depth of ploughing ; and 

 when that is too shallow, the gradual deepening of it should 

 be sought by the use of proper materials for improvement 

 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 and subjected to 

 the meliorating influence of cultivation, they will frequently 

 produce a soij of great value. 



