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



The percentage of humus in each of the above soils is very 

 low, especially in that of the red loam of the Redlands mesa. 

 The percentages decrease steadily into the lower portions of each 

 colunui. 



The Highlands sandy soil is the richer of the two, both in 

 humus and nitrogen, and in the entire column except the upper 

 three feet is fairly supplied with each of these. 



The Redlands soil, because of its heavier clay nature, would 

 be more benefited by green-manuring than would that of High- 

 lands. 



South-side Mesa. — On the south side of the valle,y the mesa 

 rises from near the border of Santa Ana River and extends to 

 the hills at elevations much above the plains. The soil is very 

 generally a reddish clay loam, more or less gravelly, and overlies 

 granitic debris at depths of many feet. 



Table 34. — Humus in Soil Columns of South-side Mesa of 

 San Bernardino Valley 



