406 University of California Publications in Agricultural Sciences [Vol.3 



Table 19 — Humus (and Humus Ash) 

 Han ford Fine Sandy Loam 



Diablo clay adobe. — The variation in these samples was from 

 5.6% to 8.6%, with the average of 6.8%. The Altamont clay loam 

 has a variation of from 5% to 8.7%, averaging 6.7%. The San Joa- 

 quin sandy loam has a range of variation between 1.6% and 4.2%, 

 with an average of 2.6%. The loss on ignition of the lower horizons 

 increases over that' of the surface, because of the increase in texture. 

 The B horizon shows an average loss of 3.9% and the C horizon of 

 4.67%. The Hanford fine sandy loam range of variation in the loss 

 on ignition is, excluding no. 14, from 2.2% to 3.9%, with an average 

 of 3.4%. Thus the curve for this type is quite uniform, except for 

 no. 14, which shows a loss of 6.9%. 



It is seen that the averages in the loss on ignition of the A horizons 

 of the Diablo and Altamont soils are close, and high, 6.8% and 6.7% 

 respectively. The averages of the San Joaquin and Hanford sam- 

 ples, 2.6 % and 3.4% respectively, are low and not widely separated. 

 Since the values for the types overlap considerably, and the averages 

 are not distinct, except between the light and heavy groups, there is 

 no significant distinction between the four types by this determination. 



