27] Boden und Gewässer 283 



the planted soil and ils uncropped duplicate. 3. Notable differences were 

 observed between tbe nitrates, calcium, potassrum, and magnesium present in tbe 

 water extracts from tbe cropped and uncropped soils. 4. Tbe phosphates did not 

 exhibit eorresponding differences. Great dissimilarities were observed in the 

 phosphate content of different soils, but in any one soil tbe amount was 

 practically constant in botli tbe cropped and uncropped plot. 5. Striking 

 differences occured between the soluble nutrients present in tbe various un- 

 cropped soils. 6. Wliile the crops were growing the concentrations of nutrients 

 in 8 of the 16 planted soils were practically the same. These 8 included both 

 good and poor soils. 7. The three poorest soils yielded the smallest amounts 

 of w T ater-soluble nutrients and the smallest differences betw T een the cropped 

 and uncropped duplicates. 8. The comparisons betw T een the planted and un- 

 planted duplicates furnished valuable indexes of the inherent capacities of 

 the soils to produce nutrients. 9. The accuracy of the methods of analysis 

 and of the extract ion procedure employed was determined, and the mean and 

 maximum errors involved were estimated. 10. The amounts of the water- 

 soluble nutrients obtained by varying the ratio of soil to water were studied. 

 The relationship of the Compounds extracted did not change essentially in the 

 lower concentrations. 11. By comparison with freezing-point determinations 

 the concentration of tbe soil Solutions calculated from the water extract was 

 shown to be from two to four or five times as great as the actual soil 

 Solution. 12. Variations in tbe water extract were correlated with variations 

 in the freezing-points of the same samples of soil. 13. From tbe results of the 

 freezing-point determinations it is concluded that variations in the water 

 extract reflect actual changes in the soil Solution. 14. The results of the 

 investigation sbow that large amounts of water-soluble nutrients are developed 

 by cultivation, fallowing, and biennial cropping, and demonstrate the sound- 

 ness of these practices." 



213. Stutzer, A. Beziehungen zwischen der Reaktion des 

 Bodens, dem Auftreten von Pflanzenkrankheiten und 

 der Entwicklung gewisser Pflanzen. (Fühlings Landw. Zeitg. 

 66, 1917, p. 131.) — Ref. in Ctrbl. Biochem. Biophysik 19, 1918, p. 395. 



214. Tanim, Olof. Om skogsjord analyser. [Über Waldboden- 

 analysen. Schwedisch mit ausführlicher deutscher Zusammenfassung.] (Mitt. 

 Forstl. Versuchsanst. Schwedens XIII— XIV, 1916/17, p. 235—260, p. XXV bis 

 XXVI II.) — Bemerkungen über die Bedeutung von Waldbodenanalysen nebst 

 Beschreibung der an der Forstlichen Versuchsanstalt Sclnvedens benutzten 

 Methoden zur Bestimmung von Kalk, Phosphorsäure, Humusgehalt, Gesamt- 

 eisen und Limonit. C o 1 1 a n d e r. 



215. Traeen, A, E. Über den Einfluß der Feuchtigkeit 

 auf die Stickstoffumsetzung im Erdboden. (Ctrbl. f. Bak- 

 teriologie, 2. Abt., 45, 1916, p. 119—135.) - - Ref. in Bot. Ctrbl. 1918, 138, p. 4. 



216. Trousoff, A. S t u d i e n über die Humusbildu n g d u r c h 

 Pflanzen unter spezieller Berücksichtigung der natür- 

 lichen Verhältnisse in R u ß 1 a n d. (Selskoie Khosiaistwo i Lilso- 

 wodstwo 147, Petersburg 1915, p. 575—605.) — Ref. in Bot. Ctrbl. 1917, 134, 

 p. 193. 



216a. Trousoff, A. Die Humif izierung der Pflanzenbe- 

 standteile. (Selskoie Khosiaistwo i Lilsowodstwo 248, Petersburg 1915. 

 p. 409—437.) — Ref. in Bot. Ctrbl. 135, 1917, p. 51. 



