UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



AGRICULTURAL SCIENCES 



Vol. 1, No. 8, pp. 173-274 August 25, 1914 



HUMUS AND HUMUS-NITROGEN IN ^ 



CALIFORNIA SOIL COLUMNS ^or, 



BY 

 E. H. LOUGHRIDGE 



CONTENTS p^^g 



Introduction: character of humus, amount produced from various sub- 

 stances; distribution in surface soil .• 174 



Humus in California Soils: percentages in the surface foot acording to 



agricultural regions, by quick and regular analyses 176 



Distribution of Humus downward in California Soils: bacterial activity 



in the lower depths of soil columns 179 



Distribution of Humus and Humus-nitrogen in soil columns from each 



agricultural region of the state 180 



Sacramento Valley: eighteen soil columns; tables of analyses 181 



Alluvial lands, four localities; clay loams, seven localities 181 



Black adobe soils, four localities; Red mesa, three localities 186 



Comparison of classes or types 190 



San Joaquin Valley: twenty-four soil columns; tables of analyses. 191 



Sandy loams and clay loam lands, ten localities 192 



Gray alkali lands, four localities 196 



Black clays, loam, and reddish clays, eight localities 197 



Delta plains of Kings and Kern rivers, three localities 201 



Eiver alluvial lands and Tule marshes, two localities 203 



Comparison of soils of different types 204 



Lower Foothills of Sierra Nevada: three soil columns; analyses 208 



Coast Range Valleys: twenty-four soil columns; tables of analyses. 209 

 North of Bay Region: Russian River, Santa Rosa, Los Guillocos, 



Sonoma, Napa, and Vaca valleys 210 



The Bay Region: Alameda Plains, Ignacio, San Ramon, and 



Livermore valleys 214 



South of the Bay Region: Santa Clara, Pajaro, Salinas, Arroyo 



Grande, Santa Maria, and Lompoc valleys 217 



Summary of results for Coast Range 223 



Southern California Region: twenty-six soil columns; analyses 225 



Saticoy Plain, Santa Clara River delta. Pleasant Valley hill 



slope, San Fernando and San Gabriel valleys 226 



San Bernardino plains, lowlands and mesas; Los Angeles plain. 230 

 Interior Valleys: Fallbrook mesa, Perris, Escondido, and El 



Cajon valleys 238 



Summary for Southern California columns 240 



Northeastern Lava-bed Region: seven columns; tables of analyses. 241 

 Honey Lake Valley; East Honey Lake Valley, Madaline Plains, 

 Pitt River Valley, Klamath Lake marshes, Surprise Valley.... 241 



