1914] Lougliridge: Humus and Nitrogen in Calif ornia Soil Columns 261 



The marsh or tiile soils of the state have very high amounts 

 of nitrogen, as shown in the Stockton tule (0.83 per cent), 

 Klamath tule (0.34 per cent), and the Pomona cienega (0.25 per 

 cent). The nitrogen is, however, less available than that of 

 the dry uplands, and a comparison cannot be made. The two 

 soils from the Arroyo Grande Valley, including the Routzahn 

 seed-farm, are highest among the other soil columns with their 

 0.16 per cent of nitrogen each ; the next highest are Gilroy with 

 0.15 per cent ; Berkeley and Farmington each with 0.14 per cent ; 

 Burpee seed-farm of Lompoc, Vaca Valley, and Kenwood each 

 with 0.13 per cent; and El Verano, Santa Maria. Chico, Yount- 

 ville, and Chino each with 0.11 per cent. Newcastle soil has 

 0.10 per cent, while all others have less than that. The results 

 show most certainly that the lands represented by these fourteen 

 soils should not need fertilization with nitrate fertilizers for 

 many years. 



Nine of the soils have but 0.01 per cent of humus-nitrogen in 

 the first foot, seven have but 0.02 ; forty-six or nearly half of 

 the columns have less than 0.05 per cent, and hence are much 

 below the desirable percentage of nitrogen. The average of the 

 first foot of all of the columns, except the marshes, is about 

 0.05 per cent. 



Some of the upland soils are quite rich in organic nitrogen in 

 the upper three feet, the true soil of the arid region. The adobe 

 of Berkeley is the richest with its 0.13 per cent or approximately 

 15,000 pounds per acre in a depth of three feet. Eight columns 

 have averages of 0.10 and upward, viz., the two Arroyo Grande 

 soils, Gilroy, Chico, Farmington, Kenwood, Newcastle, and 

 Cottonwood. Thirty-one columns have averages of from 0.06 

 to 0.10 per cent, all others being below this amount. In other 

 w^ords we find that more than half of the columns have less than 

 the 0.05 per cent of organic nitrogen in their upper three feet 

 which is considered necessary for fertility. Many have but little 

 more than traces of nitrogen. 



In the entire column of twelve feet we find that there are 

 eleven upland localities that have averages of as much as 0.05 per 

 cent, and among these Berkeley and Arroyo Grande columns 

 stand highest with averages of 0.08 per cent or approximately 



