62 CHEMISTRY OF FARM PRACTICE 



the cross-section area of the capillary spaces and by the 

 strength of the liquid film at the upper surface of these 

 spaces. The smaller the area of the capillaries the greater 

 will be the distance through which the water will rise. 



Every care should be exercised to increase the supply 

 of moisture by the prevention of evaporation and per- 

 colation. The available moisture is increased and the 

 surface washing is decreased by deeper preparation of 

 the soil, which offers a larger reservoir for the retention of 

 water. Then, too, surface washing can be greatly lessened 

 by the practice of terracing, which is quite extensively 

 used in the Southern States, and also by the use of rotations 

 that do not have many clean-cultured crops in them. The 

 evaporation can be greatly lessened by shallow cultivation, 

 during the growing season, which serves to form a soil 

 mulch, destroys the surface capillarity, and retains moisture 

 very effectively. The retention of the largest possible 

 amount of the moisture serves a two-fold purpose: It adds 

 to the available moisture, which is often the limiting factor 

 of production, and it lessens the surface washing. In no 

 way are our clean-cultured, rolling lands depleted more 

 than by surface washing, and its prevention is worthy of 

 the close consideration of those who own or cultivate such 

 lands. 



For best soil conditions, the gravitational water should 

 sink deep into the soil as rapidly as possible, in order that 

 the capillary action may be at its best. Where the drain- 

 age is good, the gravitational water is no trouble. Deep 

 fall plowing, the incorporation of organic matter, and com- 

 paratively shallow cultivation after each rain, in order to 

 form a soil mulch, are the secrets of the conservation of 

 moisture. 



