UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



AGRICULTURAL SCIENCES 



Vol. 1, No. 1, pp. 1-20 Issued October 15, 1912 



THE DISTRIBUTION AND ACTIVITIES OF 



BACTERIA IN SOILS OF THE 



ARID REGIONS* 



BY 



CHAELES B. LIPMAN 



INTRODUCTION 



The student of soils in the humid region, when for the first 

 time exploring soils in the arid region, is invariably struck with 

 the extraordinary depth of the latter as against the very shallow 

 nature of the former. Taken by and large, and excepting the 

 faulty soils, including those underlaid at no great depth by stiff 

 clay, coarse gravel, hardpan, or original rock, respectively, the 

 soils of the arid region very commonly show a depth of at least 

 eight to ten feet, and, when viewed in section, exhibit such a 

 striking uniformity in texture and color as to attach to this 

 unusual condition, in the mind of the observer, a certain marked 

 practical and scientific interest. The full significance to crops of 

 the arid region of this extraordinary condition in our soils was 

 first realized and pointed out by Ililgard and was made the 

 subject, by him and Loughridge, of a comprehensive investiga- 

 tion on the "soil-columns" of California, a large part of which 

 is completed, but some of which is still in progress. The study 

 of the soil-columns of California comprised what might be 

 looked upon as a very thorough partial soil survey of Cali- 

 fornia. It was the intention of the investigators above named, 

 at the inception of the work, to obtain columns of soil repre- 

 senting depths of twelve feet, including a sample for every foot 



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 WEW YORK 

 BOTANICAL 



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* Eead before the Society of American Bacteriologists, Washington, 

 D. C, December 27, 1911. 



