SOIL INOCULATION 831 



where. No introduction of Azotobacter will help to establish this or- 

 ganism in the soil and bring about increased nitrogen fixation in an acid 

 soil with a pH less than 6.0. However, the addition of lime to change 

 the pH to above 6.0 will by itself bring about a development of an active 

 nitrogen fixing flora, of course if other conditions are favorable. Good 

 results from inoculation may be obtained in the case of freshly 

 drained swamps, in which Azotobacter would be absent. 44 But the 

 reaction of the soil must first be adjusted by the use of lime. 



All attempts to inoculate normal soils with Azotobacter and other 

 non-symbiotic nitrogen-fixing organisms failed on repeated study. 

 From Caron's "alinit" 45 in 1895 to Bottomley's 46 "bacterized peat," 

 all attempts to exploit commercially the nitrogen-fixing capacity of 

 Azotobacter and other bacteria failed. 47 The soil itself harbors suffi- 

 cient organisms which become active when conditions and nutrients are 

 favorable, as shown by Gainey for Azotobacter. Hiltner 48 claimed to 

 have obtained good results from inoculation of sugar beets with bac- 

 teria; just what these bacteria do in the soil, has not been determined. 

 The U-cultures of Kiihn, 49 which are also used as an all-crop inoculant, 

 have been found worthless by Barthel. 50 



Ehrenberg 51 compared soil inoculation with symbiotic and non-symbio- 

 tic nitrogen-fixing bacteria, with the following conclusions: 



1. On comparing the abundance of the various bacteria living in the soil, hardly 

 any change takes place as a result of artificial inoculation, since the bacteria 



44 Stoklasa, J. Deut landw. Presse 1908, No. 25-27; Stranak, Fr. Zur 

 Assimilation des Luftstickstoffes durch im Boden freilebenden Mikroorganismen. 

 Centrbl. Bakt. II, 25: 320-321. 1909. 



45 Caron, A. Landwirtschaftlich-bakteriologische Probleme. Landw. Vers. 

 Sta., 45: 401-418. 1895; see also Stoklasa, J. Biologische Studien uber Alinit. 

 Centrbl. Bakt. II, 4: 39-41, 78-86, 119-130, 284-289, 507-513, 535-540. 1898; 

 Deut. landw. Presse, 35: 274, 286-297. 1908; Heinze, B. Uber die Beziehungen 

 der sog. Alinit bakterien (Bac. ellenbachiensis Caron) zu dem Bac. megatherium 

 deBary bezw. zu den Heubacillen (B. subtilis Cohn). Centrbl. Bakt. II, 8: 

 391, 417, 449, 513, 545, 609, 663. 1902. 



46 Bottomley, W. B. Rpt. Brit. Assn. Adv. Sci. 1911,607-608. 



47 Russell, E. J. Report on humogen. Jour. Bd. Agr. (London), 24: 11-20. 

 1917. 



48 Hiltner, L. Uber die Impfung der Putter und Zuckerruben. Mitt. Deut. 

 Landw. Gesell., 26: 243. 1921; Engelmann, E. Mitt. deut. Landw. Gesell., 

 37: 560. 1922. 



49 Ktihn. Deut. Landw. Presse, 44: 467. 1917. 



60 Barthel, Chr. Forsok med Dr. A. Kuhns U— Kulturer. Meddl. No. 184, 

 Centralanst. f. forsoksv. jordbruks. 1919; Deut. Landw. Presse, 50: 192. 1920. 



61 Ehrenberg, P. Theoretische Hinweise zur Frage der Wirkung einer Boden- 



