•>80 University of California Publications in Agricultural Sciences [Vol.3 



discrepancies in the reactions between different soils and CaCCX. or 

 CaS0 4 , which we have been studying. While thus we are in apparent 

 disagreement with the principle of the indirect results of Lyon and 

 Bizzell regarding the effect of lime on the calcium content of the soil 

 solution, we are not actually so. On the other hand, we are in actual 

 agreement with them as regards the effect of calcium applications on 

 the magnesium content of the soil solution. In all soils studied by us, 

 we find increases of magnesium in the soil solution, due to CaCO.. 

 applications, but this does not imply that the same would hold for 

 all other soils. Again, we are in agreement with the indirect results 

 of Lyon and Bizzell regarding the sulphur content of the soil solution 

 as affected by lime applications in the case of the greenhouse soil, but 

 not in the case of the clay adobe soil, and probably not in the case 

 of the blow sand. 



If we may repeat, therefore, we are apparently forced to conclude, 

 from the results of our experiments and from such comparisons of 

 them with those of others as we can make, that no general idea of the 

 effect of CaCO H or of CaS0 4 on the potassium content of any other ion 

 in the soil solution can be adduced from any one soil or from any one 

 general kind of soil. In some soils, large accretions of soluble potas- 

 sium to the solution may be obtained by CaC0 3 or by CaS0 4 applica- 

 tions ; in others no increases may be obtained. This may hold for any 

 ion, but does not preclude the probability that some ions may be 

 rendered soluble in larger amounts by CaC0 3 in any soil. Whether 

 or not the ions which are rendered soluble in greater amounts by the 

 application to the soil of CaC0 3 or CaS0 4 , or both, are also available in 

 such larger amount to the plant roots is another question, an affirmative 

 answer to which does not necessarily follow from such an answer to the 

 question which we are discussing here. It is to be noted from our 

 results, also, that the time of the year at which ions are sought in the 

 soil solution, or at least the period elapsing between the application 

 of CaC0 3 or of CaS0 4 to the soil and the sampling of the latter, are 

 important factors in determining the results of one's findings and 

 cannot be overlooked in any such investigations. 



In anticipation of queries which may arise from readers of the fore- 

 going discussion, we desire to make very clear and emphatic the follow- 

 ing general statement. We do not believe that all of the data given 

 by us in the tables are significant, because we appreciate the large 

 error which probably attaches to our method of obtaining the soil 

 extract and of analyzing it. Our calculations are such, therefore, as 



