CAMPBELL'S SOIL CULTURE MANUAL 7 



merit of what has come to be known in a dozen or more 

 states as the Campbell system of soil culture; shall tell 

 why and how I came to make the investigations which 

 led up to this; shall discuss freely the principles which 

 lie at the foundation; shall tell what has been accom- 

 plished and what may be expected; and I shall give here 

 instructions as to how to apply these principles as nearly 

 complete as possible. 



In previous editions of the Manual, and in various 

 other publications and in public addresses, commencing 

 a dozen years ago, I have insisted that science in soil cul- 

 ture and the more perfect adaptation of scientific methods 

 to farming would result in doubling the crops in the great 

 semi-arid belt of America. In later years I have made 

 the statement still stronger and have declared, to the 

 amazement of some of the doubting ones, that crops have 

 not been one-fourth what they should have been in this 

 region. It is because I have had faith in this region and 

 have been confident that crops could be made as certain 

 here as elsewhere, that I have pursued investigations, 

 often under the most discouraging conditions and in the 

 face of fierce opposition, and it is in the hope that I may 

 convince others, not a few but thousands, that I publish 

 this Manual. 



While the investigations which have resulted in the 

 development of this system of soil culture have been car- 

 ried on in the semi-arid belt, or that region where the rain- 

 fall is too small for successful farming in the ordinary 

 way, it should be understood at the outset that the prin- 

 ciples are applicable anywhere and in any climate, and 

 that even where there is an excess of moisture, those who 

 make use of the system will achieve results of great value. 

 The difficulties to be overcome by the farmer in assuring 



