216 University of California Publications in Agricultural Sciences [Vol. 1 



Livermore Valley. — The soil of the valley is a loam while that 

 of the low hills of the west and south is reddish and gravelly. 

 A column was taken to a depth of ten feet from the plain in the 

 Santa Rita region, Alameda County. 



Table 21. — Humus in Soil 



Ignacio Valley 

 CONTRA COSTA COUNTY 



Columns of Valleys East 



San Raaion Valley 

 CONTRA COSTA COUNTY 



OF Contra Costa Hills 

 Livermore Valley 



ALAMEDA COUNTY 



Santa Rita 



Humus- 

 Soil Nitrogen in 



Clay 10.60 , ^ ^ 



Humus Humus Soil 



Sandy loam .. .64 8.78 .06 



Sandy loam.. .83 6.03 .05 



Sandy loam.. .55 5.62 .03 



Sandy loam.. .45 3.10 .02 



Reddish loam .34 3.23 .01 



Reddiish loam .37 3.78 .01 



Reddish loam .43 2.57 .01 



Sand 24 3.33 .01 



Sand 28 2.14 .01 



Sand 33 4.25 .01 



4.46 



.45 4.28 .02 



2.02 

 .67 6.81 .04 



* Range of most annual plant roots. 



In these two groups of six soils, the adobe clay from Berkeley 

 is the richest in every respect, while that from Walnut Creek 

 is next. High percentages of humus are found to a greater depth 

 in them than in any other of the columns. The Berkeley clay 

 changes color below the fourth foot from black to yellow, while 

 that from Walnut Creek remains dark throughout its twelve 

 feet. The same change from black to gray occurs in the San 

 Ramon adobe below the fourth foot, and each of its upper three 

 feet contains more than 1 per cent of humus. A change from 

 dark to red occurs in the loam soil of Santa Rita in Livermore 

 Vallev. 



