12 



THE SOII, SOLUTION 



conservative, let it be assumed that 60 Ibs. of potash have been 

 added to 3,000,000 Ibs. of soil. The official method of the 

 Association of Official Agricultural Chemists calls for the de- 

 termination of the potash in 2 grams of soil, which on the basis 

 of the present assumption calls for the estimation of an added 

 amount of 0.00004 gram potash or 0.002 per cent. Taking 

 as an example the report of the Association of Official Agricul- 

 tural Chemists for 1895* there are given the following results 

 obtained independently by a number of analysts, on soils which 

 had presumably been sampled by the referee with all possible 



care: 



POTASH CALCULATED As PER CENT. OF THE FINE DRIED EARTH. 



Not only do the individual determinations show differences 

 far in excess of 0.002 per cent., but the differences between each 

 individual reading and the mean is greater than 0.002 per cent., 

 so that it is evident from these results that the analytical pro- 

 cedure fails to recognize appreciable amounts of the so-called 

 available plant foods. Consequently the "acid digestion" of a 

 soil fails of the purpose for which it was designed, and it is one 

 of the mysteries of chemical history that so much time and energy 

 have been devoted to such a hopeless quest. 



This state of affairs is the more surprising when the lim- 

 itations of the analytical procedure are considered. The data 



1 Proceedings of the Twelfth Annual Convention of the Association 

 of Official Agricultural Chemists, Bull. No. 47, Division of Chemistry, 

 U. S. Dept. Agriculture, p. 36 (1896). 



