THE SOIL SOLUTION 



by analyzing solutions extracted from different samples of loams 

 and sands by means of a centrifuge. The crop growing on these 

 soils and the crop condition at the time the samples were col- 

 lected are given in the table, and the percentages of water in 

 the samples when placed in the centrifuge are also given. 



ANALYSIS OF SOIL SOLUTION REMOVED FROM FRESH SOILS 

 BY THE CENTRIFUGE. 



The concentrations of the solutions obtained from the samples 

 do not justify any correlation with the crop-producing power 

 of the soils, nor with the texture of the soils. The wide varia- 

 tion in the concentrations with respect to calcium is probably 

 due to the fact that all of the samples came from fields which 

 had been limed, some quite recently, and that the content of 

 carbon dixoide in the different samples varied. It is of special 

 interest to note that the content of calcium in the solutions does 

 not show any obvious relation to the conent of phosphoric acid. 1 



An effort has been made to ascertain the mineral concentra- 

 tion of soil solutions as they occur naturally in the field. Be- 



1 For the literature of the earlier work on the composition of aqueous 

 extracts of soils, see : How crops feed, by Samuel W. Johnson, 1890, 

 p. 309 et seq. ; see also, On the analytical determination of probably avail- 

 able "mineral" plant-food in soils, by Bernard Dyer, Jour. Chem. Soc., 65, 

 115-167 (1894) ; and Soils, by E. W. Hilgard, 1906, p. 327 et seq. 



