276 I'/iin rsity of California Publications in Agricultural Sciences [Vol. 3 



soluble phosphorus and the water soluble sulphur in that soil have been 

 affected by CaCO., and the first by CaS0 4 . The calcium content of 

 the solution is affected by both CaC0 3 and CaS0 4 , as would be ex- 

 pected, but which does not necessarily have to occur. On the other 

 hand, the water soluble iron content of the soil appears possibly to 

 be slightly affected by the CaCO, treatment, at least in the first 

 sampling; and the magnesium content of the water extract shows, it 

 seems to us. very distinct accretions, through the CaC0 3 applications, 

 in the first and second samplings. The effect seems to have dis- 

 appeared, however, by the time the third sampling was made and a 

 new equilibrium is probably established. On the contrary, gypsum 

 seems to depress the amount of water soluble magnesium in the soil 

 solution of the Oakley soil. This appears to be definitely true by the 

 time the period of the second sampling has been reached, and less 

 definitely in the period of the first sampling with the larger gypsum 

 application. Just as the tendency to increase in amount in the soil 

 solution through the instrumentality of the treatment seems to char- 

 acterize both the ions, magnesium and iron, in the periods up to and 

 including the second sampling, a reverse tendency is manifested by 

 these ions by the time of the third sampling. In the soils treated with 

 CaCOo, there is a definite decrease in magnesium, in the solution, in 

 the period named and the iron content of the same soil solutions seems 

 to decrease simultaneously. Yet the other ions do not seem to have 

 been affected in that way in the same period, but have either remained 

 stationary or have shown increases. These rather marked changes 

 evidenced by the figures of the second and third samplings are even 

 more distinct in the cases of the other soils, to which reference will be 

 made below. 



In the Berkeley clay adobe soil, the data for which are given in 

 table 2, conditions are quite evidently not the same as in the Oakley 

 soil. While the potassium content of the latter soil's solution remained 

 unaffected by the application of either CaC0 3 or CaS0 4 , that of the 

 former soil seems to us to be definitely increased by both CaCO., and 

 CaS0 4 in the first two samplings and by CaS0 4 alone in the last 

 sampling. The greater effect in that direction is clearly induced, how- 

 ever, by CaC0 3 . The iron content of the soil solution in the clay 

 adobe soil remains entirely unaffected by the treatment which is 

 accorded the soil. The phosphorus content of the soil solution affected 

 by CaCO., may, perhaps, be slightly increased in both the second and 

 third samplings, but the data do not give us leave to be certain on 



