10 CAMPBELL'S SOIL CULTURE MANUAL 



many varied conditions, and to explain the reason for 

 doing certain things then to leave it to the intelligent 

 direction of the farmer to do the rest. These general 

 principles relate to soil physics, to the character of the 

 soil, the texture of the soil, the movement of moisture 

 in the soil, the development of soil fertility or those ele- 

 ments essential to plant growth, and what can be done 

 and must be done by cultivation to affect the quantity 

 and quality of the crop. One who comprehends clearly 

 these principles and labors with the knowledge that is in 

 him, will find the way to profitable agriculture. 



There can be no universal rule for the cultivation of 

 the soil. Conditions are so different that there must be 

 variation. Everyone knows that drainage is necessary 

 to some soils in some climates. It is not so well under- 

 stood that where the rainfall is insufficient there can 

 be conservation of the moisture by cultivation. Neither 

 is it generally known that by and through cultivation of 

 the soil there is brought about great changes in the phys- 

 ical condition so that soils having but little available fer- 

 tility may be strengthened and others burdened with 

 plant elements are modified. Some important general 

 rules may be applied, however, in the semi-arid region, 

 so that they may be followed with assurance that there 

 will be conservation of moisture and development of plant 

 elements and the consequent growth of crops equal to 

 those grown in the more humid regions of the country. 



It ought not to be difficult for any one to recall facts 

 and incidents which have come under his personal ob- 

 servation tending to prove the main arguments in sup- 

 port of our position. Take, for instance, the very common 

 incident of a large plant growth occurring right where 

 there had been the previous winter a large drift of snow 



