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



San Gabriel Valley. — This valley lies east of Los Angeles and 

 reaches from the mountains southward to the alluvial plains. It 

 is watered by the San Gabriel River and bordered on the east by 

 the Puente Hills, and the San Antonio debris cone. Its soil is a 

 sandy loam. A column of soil was taken by Mr. F. E. Johnson 

 from the neighborhood of Covina and "represents an average of 

 all of the different soil types." Another column was taken by 

 ]\Ir. Johnson from near Monrovia and represents the heavier type 

 of soil, the greater part of which is sandy and gravelly wash 

 from the hills. 



These soils are quite deficient in the necessary amount of 

 humus to keep them in good physical condition and to furnish 

 adequate nitrogen for the plants. 



Attention of orchard growers should especially be given to 

 the yearly growing and turning under of the best leguminous 

 crop available — a crop giving large yields of succulent, easily 

 decomposed stems and leaves and containing high percentages 

 of nitrogen. Until a fair supply of humus in the three upper 

 feet are secured by this method, it seems necessary to apply 

 nitrogen fertilizers to the trees with sufficient irrigation water 

 to carry them down to the feeding roots at a depth of several 

 feet below the surface. 



San Bernardino Valley. — The eastern portion of the valley of 

 Southern California known as the San Bernardino Valley is 

 separated from the western by a range of low hills and by the 

 debris cone of the San Antonio Creek, which issues from its 

 valley just above Pomona and supplies most of the water to 

 Chino Creek which empties into the Santa Ana River. In the 

 past from time to time, a portion of the San Antonio flow has 

 been diverted into the San Gabriel. 



The valley covers a large area and comprises a large variety 

 of soil types, a few of which are represented by soil columns. 

 The valley slopes toward the south to the Rineon Basin and 

 Santa Ana River, and is bordered by a rim of mesa land on the 

 north, east, and south. 



The Valley Plains. — The soils in the central part of the valley 

 are chiefly of a sandy nature, of excellent depth and good fer- 

 tility. The lowlands are usually highly charged with alkali that 



