634 



SECTION VI 



COMPOSITION OF SOME EUROPEAN SOILS 



THE data relating to the composition of European soils are very 

 incomplete, and the analytical methods used have been far from uniform. 

 A good compilation of these data from Germany, France, and the United 

 Kingdom is contained in Bulletin 57 (1909) of the United States Bureau 

 of Soils, giving principally the results secured by digesting the soils 

 with strong acids. This compilation includes no nitrogen determina- 

 tions, but the phosphorus, potassium, and calcium are usually given, 

 and sometimes the magnesium, chiefly in terms of the oxids. 



In the Rothamsted laboratories, after previous ignition of the soil, 

 very strong hot hydrochloric and nitric acids are employed in soil 

 analysis, and probably this method is used quite generally in Great 

 Britain. If so, the data for phosphorus will closely approach the total. 

 In Germany cold hydrochloric acid is the common solvent used, and 

 the results thus secured are not comparable with those of England. 



Four analyses by Burguy (Inaug.-Diss. Berlin, 1899) show as an aver- 

 age 41,330 pounds of potassium (evidently total) in two million of the 

 loess soil of North Germany. (The phosphorus content of this soil is 

 not given.) About 450 analyses of German soils are reported in this 

 compilation, but for the reason given above they signify but little to the 

 student of permanent agriculture. Wohltmann, as Director of the Insti- 

 tute for Soil and Crop Investigations, Bonn-Poppelsdorf, in. a report 

 (1901) on "The Fertility-Invoice of West-German Soils" ("Das Nahr- 

 stoff-Kapital West-Deutscher Boden"), shows that the cold acid which 

 he used generally dissolved about one fourth as much potassium from 

 soils as hot acid (which he also used for additional potassium deter- 

 minations), but the proportion varied with different soils from about 

 one seventh to one half. A trial with a single soil showed that digestion 

 with hot acid for 12 hours, dissolved one third more phosphorus than 

 digestion with cold acid for 48 hours ; and numerous other experiments 

 have shown that as an average the ordinary 10 hours' digestion with 

 hot hydrochloric acid will dissolve only 85 per cent of the total phos- 

 phorus, and with some soils less than one half of the total is thus dis- 

 solved. 



Wohltmann concludes from extended chemical and cultural investiga- 

 tions that in West Germany soils which contain less than 1200 pounds 



