1914] Loughridge: Humus and Nitrogen in California Soil Columns 249 



Table 42. — Humus in Soil Columns of Other Valleys 



Range of most annual plant roots. 



penetration. It, however, supported a growth of yucca and 

 desert weeds, and on the same mesa, near Hesperia, with pre- 

 sumably the same soil though deeper, there are a few orchards. 

 A glance at the table shows that there is nearly the same per- 

 centage of humus in the first foot of each of the columns and 

 very little difference in the total amount in the upper three feet. 

 The very unequal distribution in the El Centre column is 

 somewhat surprising, for it might readily be supposed that the 

 small amount in the surface foot would indicate that there was 

 scarcely any in the lower depths; whereas we find higher per- 

 centages in the fourth, fifth, eighth, and tenth foot respectively 

 than in either of the upper three feet. It is interesting to note 

 that there is more in the lower half of the column than in the 

 upper. The humus of these columns is not quite as rich in 

 nitrogen as are the soils from other parts of the state, and that 

 of the Bishop column is extremely low. The nitrogen of the soil 

 is not more than 0.01 per cent, or about 400 pounds per acre-foot. 



