240 University of California Publications in Agrindtural Sciences [Vol. 1 



The surface soil of the eohimii taken near Perris is badly 

 deficient in hiimus, but in each of the three feet below there is 

 a fair percentage. Green-manuring crops are called for. The 

 hill lands of Fallbrook also are low in their percentages of 

 humus and nitrogen and need nitrogen fertilizers (either through 

 nitrates, stable manure, tankage, or dried blood) as well as good 

 green-manure crops. 



The column representing the Escondido Valley is very poor 

 in humus and nitrogen, while that of El Cajon is better supplied, 

 though still much below what is needed for good texture and 

 fertility. Crops should respond to nitrate fertilization on both 

 of these soils. 



The humus in all of these soils is surprisingly low for valley 

 lands that are as productive as these. 



Summary for Southern California Soil Columns 



The following are the averages obtained by combinations of 

 the twenty-six columns, omitting the marsh of the Pomona 

 cienega : 



Per cent 



Average humus in surface foot 0.88 



Average sum of per cents of humus in upper three feet 1.98 



Average humus in each of upper three feet 0.66 



Average nitrogen in humus of surface foot 5.53 



Average nitrogen in humus of upper three feet 5.22 



Average nitrogen in surface foot of soil 0.05 



Average nitrogen in upper three feet of soil 0.04 



Average nitrogen in each of twelve feet of soil 0.02 



These percentages are all too low and indicate the great need 

 of good green-manuring treatment for a number of years to 

 build up the upper three feet of soil into a high fertility. This 

 is needed more than phosphate fertilization. 



There are but six of the twenty-five soils whose surface foot 

 contains more than 1 per cent of humus ; there are but five others 

 that have more than 0.75 per cent, and there are five whose 

 humus falls even below 0.50 per cent. 



The lands represented by these columns from Southern 

 California are under such continuous cultivation that the surface 

 foot is hardly a proper unit of comparison ; a depth of three feet 



