1914] Loughridge: Humus and Nitrogen in Calif ornia Soil Columns 203 



nitrogen, but in the three upper feet of each of the columns both 

 humus and nitrogen are below the minimum for fertility. 



River Alluvial Lands and Tule Marshes. — The rivers of the 

 San Joaquin Valley are usually bordered by narrow bottom 

 lands, the JMerced and Kings rivers being exceptions where they 

 enter the valley plains. A column of eight feet depth was taken 

 by Mr. F. E. Johnson from the land of Kings River near Kings 

 River Post Office, and is the only representative of such lands 

 from this valley. The surface soils of other streams have, how- 

 ever, been examined from time to time and their humus content 

 ascertained. 



The tule marshes cover a very large region at the junction 

 of the San Joaquin and Sacramento rivers and are divided up into 

 "islands" by many sloughs. The soils of these islands is shallow 

 and peaty though rich, and water appears at but a few feet below 

 the surface. There are localities, however, where a deep soil may 



Table 16. — Humus in Columns of 

 River Alluvial 



FRESNO COUNTY 



Kings River P. 0. 



Humus- 

 Soil Nitrogen in 



Clay 4.58 , -^ ^ 



Ft. Humus Humus Soil 



1 Sandy 1.29 4.25 .06 



2 Sandy 77 4.38 .03 



3 Sandy 44 4.47 .02 



4 Sandy 33 3.83 .01 



5 Sandy 31 3.62 .01 



6 Sandy 17 4.97 .01 



7 Sandy 17 4.13 .01 



8 Sandy 19 3.72 .01 



9 



10 

 11 

 12 



Sum of per cents 3.67 



Average per foot .30 4.16 0.2 



Upper 3 feet : * 

 Sum of per cents 2.50 

 Average per foot .83 4.40 .04 



* Range of most annual plant roots. 



Lowland Soils, San Joaquin Valley 



Tule Marsh 



SAN JOAQUIN COUNTY 



Stockton 



Humus- 

 Soil Nitrogen in 



Humus Humus Soil 



Black loam 14.10 5.85 .83 



Black loam 19.45 4.82 .94 



Very black loam 16.50 5.20 .85 



Very black loam 13.00 4.41 .57 



Lighter loam .... 6.92 4.94 .34 



Lighter loam .... 2.96 4.35 .13 



Lighter loam .... 2.12 5.80 .12 



Lighter loam .... 4.28 5.09 .22 



Clay 1.44 10.14 .15 



Clay 36 2.33 .01 



Clay 34 2.06 .01 



Clay ...; 28 6.07 .01 



81.75 

 6.81 5.10 .35 



50.05 

 16.68 



5.30 .88 



