1914] Loughridge: Humus and Nitrogen in Calif ornia Soil Cohimns 181 



columns are nearly eight feet in height, thus forming a very- 

 conspicuous and interesting exhibit, probably the first and only 

 one of its kind anywhere. 



The percentage of humus and of humus-nitrogen has been 

 ascertained in all of these soils as shown in the following pages 

 of this bulletin. The chemical analysis of the first, sixth, and 

 lowest foot of each column and the physical analysis of the first 

 or upper foot have been nearly completed and the results, with 

 proper discussion, will be given in future bulletins. The humus 

 and nitrogen determinations in the bulletin were made chiefly by 

 Messrs. M. E. Holter and F. H. Wilson, and the late F. E. 

 Johnson, assistants in the soil laboratory. 



SOIL COLUMNS OF THE SACEAMENTO VALLEY 

 The valley of the Sacramento River, lying between the two 

 great mountain ranges — the Sierra Nevada on the east and the 

 Coast Range on the west — which unite on the north, covers an 

 area of 6200 square miles. The valley is widest on the south, 

 where it unites with the San Joaquin Valley. Within its area 

 are four or five general and highly distinct soil regions, or types, 

 each of which is represented by one or more soil columns in 

 our collection, or eighteen in all. 



Alluvial Lands. — These border the Sacramento River and are 

 timbered with sycamore, white oak, and ash. The soil is a dark 

 loam with little or no change to the depth of twelve feet, as shown 

 in the soil columns, and even deeper. Three columns were taken 

 from the following localities: Near Cottonwood, Shasta County, 

 by W. S. Guilford ; Glenn Post Office, in Glenn County, east of 

 Willows; and near Perkins, Sacramento County, by Professor 

 George Roberts, now of the Kentucky Agricultural College. To 

 these is added a column of the alluvial of Chico Creek taken 

 from the Bidwell place, at Chico, Butte County. 



The alluvial lands, with the exception of the sample from the 

 hop fields at Perkins, may be regarded as rich in humus in the 

 upper three feet, while all show fair amounts below that depth. 

 The soil texture is good and it is to the advantage of plant roots 

 that the humus with its nitrogen should be thus distributed, the 

 sum in each of the four columns being from 5.60 to 8.80 per cent. 



