32 



Journal of Agricultural Research 



Vol. XIII, No. I 



Table XII. — Volume weights of Tehama clay, Willows experimental tract, Willows, 

 as determined (i) upon the disturbed soil by the ordinary laboratory method, (2) upon 

 the soil in place, (a) by the rubber-tube method, (b) by the iron-cylinder method, and 

 (c) by the paraffin-immersion m,ethod 



Depth of soil. 



2 to 7 inches. 



8 to 13 inches. 

 15 to 20 inches. 

 22 to 27 inches. 

 28 to 2,3 inches. 

 35 to 40 inches. 

 42 to 47 inches. 

 48 to 53 inches. 

 54 to 60 inches. 



Average, o to 60 

 inches 



Laboratory 



method on 



disturbed soil." 



I. 38oito. 007 



I. 320± . 004 



I. 35o± . 008 



Rubber-tube 



method with soil 



in place.* 



I. 744±o. 010 



Iron- 

 cylinder 

 method 

 with soil 

 in place, c 



1.632 

 I. 721 

 I. 781 



I- 750 

 1.828 

 I. 780 



I- 732 

 1.625 



I- 731 



ParaSin- 



immersion method 



with soil 



in place. 



I. 671 ±0. 004 

 I. 702 ± 



I. 784± 



I. 802± 



I. 8o2± 



I. 792 ± 



i-757± 

 I- 747 ± 

 I. 541 ± 



008 

 007 

 002 

 007 

 000 

 012 

 010 

 028 



i-733± -035 



"Laboratory determinations were made upon composite samples from only two depths; (i) from o to 2.5 

 feet, and (2) from 2.5 to 5 feet. The results given are averages of 12 determinations from each depth. 

 * Only one depth considered in rubber-tube method, o to 5 feet. 

 _ « Depths given for iron-cylinder method are almost but not strictly accurate. Total depth covered by 

 eight samples in this method, 58 inches. Lack of rigid accuracy in depths due to slight but unavoidable 

 loss of soil in preparing each 6-inch section for the cylinder. 



As soon as it reached the spatula blades, the 6-inch column within 

 the cylinder was severed from its base, and the end was carefully smoothed 



CVLIflOER. 



Fig. 14. — Diagram showing method used for the determ.ination of the volume weight of soil by the 

 use of an iron cylinder: A. column of soil ready for determination; B, cylinder being placed over the 

 column of soil. 



flush with the cylinder, after which the soil was taken out, weighed, 

 and sampled for a moisture determination. The process was continued 

 until eight samples had been taken. These covered a total depth of 



