1914] Loughridge: Humus and Nitrogen in California Soil Columns 241 



would be more nearly correct, for in that is usually found the 

 mass of feeding roots, and no disturbing irregular conditions 

 exist. The general average of the total amount in the three upper 

 feet (sum of per cents) of the columns (omitting that of the 

 Pomona cienega) is 1.98, or an average of 0.66 per foot. This 

 is too small. 



The Santa Ana adobe and Chino moist land have each above 

 4.50 and JMound Schoolhouse has 3.11 per cent, but all others 

 fall below the latter. Six of the columns have more than 2 per 

 cent each, while on the other hand three have each a sum of 

 less than 1 per cent in the three feet, or an average of but 

 0.25 per cent per foot. 



The humus in these soils is with a few exceptions not especi- 

 ally rich in nitrogen, and, as a consequence, the soil is but 

 meagerly supplied. 



SOIL COLUMNS OF THE NORTHEASTERN LAVA-BED REGION 



The lava-bed region, comprising a large portion of the north- 

 eastern part of the state, reaches north from the Sierra Nevada 

 mountains into Oregon and is a region of lava-bed plateaus and 

 hills interspersed with occasional valleys that are capable of 

 cultivation to a large extent in grain, some fruits, and alfalfa. 



Honey Lake Valley.^ — This valley with its large lake lies 

 between the foot of the Sierras and the lava hills on the north, 

 and has an elevation of about 4000 feet above sea-level. It is 

 divided into the Honey Lake Valley proper and the East Side 

 Valley, which extends from the lake eastward into the desert 

 region. 



Honey Lake occupies the greater part of the valley and is 

 bordered on all sides by lands which are being brought under 

 cultivation in grain and alfalfa, except on the east, where the 

 soil is of a more sandy and alkali nature. A column of soil 

 was taken to a depth of ten feet from near Standish on the north 

 side of the valley; a large and luxuriant growth of alfalfa 

 covered the adjoining fields. 



6 Described by Professor Hilgard in Beport of Agricultural Experiment 

 Station, 1891-92, p. 24. 



