48 FIRST PRINCIPLES OF AGRICULTURE. 



soil. It should be deep enough to include all of the 

 surface soil, and the furrow should be turned in such a 

 manner as to subject the largest surface to the action of 

 the air. 



Narrow furrows thrown on edge expose the greatest 

 surface area to the influence of the atmosphere, while 

 a wide furrow, turned nearly flat, presents the least 

 exposed surface. The former method is best adapted 

 for heavy soils, rich in the dormant constituents, and 

 the latter more useful where the object is rather the 

 production of a good tilth or seed-bed. 



Proper plowing also greatly assists in surface drain- 

 age. The distance between the ridges is called a land, and 

 the narrower the land the better the drainage. Where 

 the natural drainage is good, ridge plowing is not so 

 important. On such lands level plowing is advisable; 

 an even surface possesses many advantages in the culti- 

 vating and harvesting of crops. 



As a rule, it is not well to bring the subsoil to the 

 surface when the planting of the crop immediately fol- 

 lows the plowing; though on alluvial soils this practice 

 is often followed for the purpose of deepening the sur- 

 face soils. 



Fall Plowing. Fall plowing is useful in economiz- 

 ing time in the spring, in improving heavy soils, and in 

 destroying many injurious insects. Land plowed in the 

 fall or very early spring is also better able to with- 

 stand drouth than if plowed immediately preceding the 

 planting of the crop, particularly if the drouth occurs early 

 in the season. 



The gradual deepening of the soil is better aecom- 



