30 



Journal of Agricultural Research 



Vol. XIII, No. I 



Table XI. — Volume weights of diferent soils as determined (/) upon disturbed soil by 

 the ordinary laboratory methods, and (2) upon soil in place by the rubber-tube method 



Name and location of tract. 



University Farm, Davis 



Hughson, Woodland 



Jackson- Wood ward, Woodland 



Guile, Woodland 



Purdy, Willows 



Tuttle, Willows 



Willows experimental tract. Willows 



Wigno, Los Molinos 



Bundy, Los Molinos 



Geer, Los Molinos 



Volume weight. 



By 



laboratory 

 method 



upon 



disturbed 



soil. 



I. 200 

 I. 220 



I- 135 

 I. 185 

 1.340 

 1.380 



I- 350 

 1.280 

 I. 200 

 1-350 



By rubber-tube 



method with soil 



in place. 



I. 28o± 



I. 2I0±0. 015 



I. 257± .007 



I. 398± 

 I. 642 ± 

 I. 74i± 



I. 75o± 



I. II2± 



I. 289± 



1. 272± 



002 

 Oil 

 019 

 010 

 019 

 001 

 013 



Percentage 

 decrease 



in volume 

 weight 



caused by 



disturbing 

 the soil. 



6.3 



— I. o 



8.8 

 15-2 

 18.5 

 20.8 

 22. 9 

 -15.0 



6.8 



- 6.0 



OTHER METHODS USED 



In order to check the above method, further studies were conducted 

 cooperatively with Prof. Charles F. Shaw, (3) of the Division of Soil Tech- 

 nology, University of California, the work being done chiefly by the 

 paraffin-immersion method employed by him at the Pennsylvania Agri- 

 cultural Experiment Station.^ Further volume-weight determinations 

 were also made by use of an iron cylinder 6 inches in diameter. The 

 procedure in the paraffin-immersion method is outlined below: A 

 hole, 3 feet wide and 6 feet long, was excavated to a depth of 5 feet 

 by use of pick and shovel. At one end steps were made in the soil for 

 convenience in getting into and out of the hole. One side of the excavation 

 was carefully smoothed and plumbed. From this side two sections of 

 soil I foot apart and of approximately i foot in cross section were ex- 

 cavated, thus leaving a vertical column i foot square and 5 feet high, 

 having three sides exposed, as represented in figure 13. The top of this 

 column was carefully smoothed by means of a spatula, putty knife, and 

 trowel. The fourth side of the column was cut from its base to a depth 

 of 6 inches with a spatula; and at the same depth below the surface 

 of the column the spatula was inserted horizontally from the three 

 exposed sides and thus a % cubic-foot sample, i foot square and X foot 

 long, representing approximately the upper 6 inches of soil, was severed 

 from the 5-foot column. The sample was placed upon the platform, as 

 shown in Plate i, B, cut into four cubes of approximately equal size, 

 the best three of which were used in determining the volume weight. 



' For a description of the method proposed by Prof. Shaw, see Brown, B. E., MacIntire, W. H., and 



CrEE, W. F. COMPARATrVE PHYSICAL AND CHEMICAI, STUDIES OF FIVE PLATS, TREATED INDEPENDENTLY 



FOR TWENTY-BIGHT YEARS. In Penn. Agr. Exp. Sta. Ann. Rpt., 1909-10, p. 96-97. 1910. 



