1914] Loughridge: Humus and Niirogen in California Soil Columns 231 



has been brought in by drainage from the higher valley. Several 

 types of soil from the plains are represented in the columns. 



Sandy loam soils of the central part of the valley are shown 

 in a column taken by jNIr. J. W. jMills from the former University 

 of California Experiment Station tract three miles southwest of 

 Ontario. 



Highly sandy soils, apparently accumulated by wind storms 

 blowing in from the mountain passes on the north, lie in the 

 central part of the valley and are extensively planted in grape 

 vines, the roots of which penetrate downward for very many 

 feet. A column of this type of soil was secured at Guasti from 

 the land of the Italian Vineyard Company. 



Alluvial plains of the Santa Ana River, known as the Victoria 

 Tract, a few miles east of San Bernardino. 



The soils of the valley plain are all quite sandy and contain 

 but small amounts of humus and of nitrogen. The tendency to 

 crust over and to form a sandy hardpan or plowsole near the 

 surface is quite usual with these soils. A succession of good 



Table 31. — Humus ix Soil 

 Southwest of Ontaeio 



Columns of Valley Lands, 

 Victoria Tract 



San Bernardino County 

 Guasti 



