MOVEMENT AND DISTRIBUTION OF MOISTURE IN 



THE SOIL 



By F. S. Harris, Director and Agronomist, and H. W. Turpin, Fellow in Agronomy, 

 Utah Agricultural Experiment Station ^ 



INTRODUCTION 



Ever since agnculture has been the subject of scientific study, soil 

 moisture in its various relations has been given a great deal of attention. 

 Following the tremendous development of the bulb industry in Holland 

 during the seventeenth century, and in view of the classic experiment of 

 Van Helmont, water was for a generation thought to be the "real food 

 of plants" and practically the only substance absolutely necessary for 

 their life. This idea naturally turned the attention of workers in agri- 

 culture toward the moisture of the soil. 



Probably no other factor so often limits crop production as does soil 

 moisture. It not only enters intimately into the plant as a food and a 

 carrier of other foods, but it also is the means by which the foods of 

 the soil are made available to the plant. In some cases it is the lack 

 of moisture and in others the presence of excessive quantities that causes 

 the difficulty. It is not often that a crop has, during its entire life, just 

 the quantity of water that best serves its needs. 



In the present paper, in which the results of thousands of determina- 

 tions are presented, an attempt has been made to throw light on a 

 number of the important phases of soil-moisture movements. Prac- 

 tically all these results are presented in diagrams which make relations 

 more apparent than does the study of long tables. Much valuable 

 experimental material is forever buried in complex tables because the 

 figures are so difficult to analyze that the reader seldom sees more than 

 the most apparent relationships. 



REVIEW OF LITERATURE 

 HISTORICAL DEVElvOPMENT OF SOIL-MOISTURE) STUDIES 



Opinions are at present not very concordant as to the extent of 

 capillary movement in the soil and as to how the moisture finally dis- 

 tributes itself under field conditions. 



The pioneer of soil-moisture work in America was King (13-15)^ who, 

 from field investigations during a number of years, concluded (16, p. 105) 

 that "what evidence we have goes to show that subsoils 6 and 7 feet 



1 The authors wish to acknowledge their indebtedness to the various members of the staff of the 

 Department of Agronomy who have contributed to this work in field, laboratory, and office. 

 'Reference is made by number to "Literature cited," p. 133-155. 



Journal of Agricultural Research, Vol. X, No. 3 



Washington, D, C. ' July '6, 1917 



Jx Key No. Utah— 7 



(113) 



