^7Z 



The nitrogen collectors {Bacillus radicicola and B. mtgaterium, Clostridium 

 Pasteurianum, Azotobacter) as also the ones forming ammonia (Bacillus 

 ureae, B. alhuminis, B. proteus vulgaris'^, B. butyricus, B. mycoides, B. sub- 

 tilis, B. mesentericus vulgatus, B. foetidus, Bacterium coprophilum, etc.) the 

 nitrifying Bacterium nitrobacter, etc., and the denitrifying genera 

 {Bacillus mycoides, B. substilis, B. liquidus, B. nubilus, B. vulgaris, B. 

 coli, B. prodigiosus, B. liquefaciens, Bacterium fuscum, Closteridium gel- 

 atinosa, etc.), have been considered and attention should now be called to the 

 specific organisms of decomposition. All these biological processes are 

 enacted in ripe soils, supplementing or combatting one another, according to 

 the climatic conditions of the soil at the time. 



Besides bacteria, green algae, the appearance of which counts as a sign 

 of good ripening, have been considered to be nitrogen collectors. According 

 to Koch^, however, this is not the case, but their value lies in the fact that 

 by their chlorophyll activity they furnish carbon for the soil bacteria, which 

 combine nitrogen. Beijerinck, Schlosing and Laurent insist that the blue- 

 green algae can assimilate free nitrogen and, according to Saida^, a number 

 of mold fungi should also have this ability. 



As Treboux* has recently emphasized, the activity of the nitrite and 

 nitrate bacteria may frequently be lost, but the ammonia retained in the soil 

 is always at the disposal of the plants and used up by them; this may still be 

 taken for granted for many cases. Other investigators have also proved the 

 usefulness of ammonia. Ultimately, however, the formation of the ammonia 

 in the soil is based on the decomposition in which bacteria participate. 



The growth of the majority of micro-organisms afifecting the fertility 

 of the soil is connected with an abundant fluctuation in moisture, and the 

 passage of heated air over the soil with its drying eflfect. These conditions 

 are lacking in heavy soils in wet periods, — i. e., the soil remains unripe. 

 Here the cultivation of useful soil bacteria succeeds only with a constant 

 working of the soil. Acknowledged practical workers recommend the 

 quickest possible turning over of the grain stubble on loamy soils in order 

 to obtain a greater nitrogen gain by an earlier soil ripening. In the Lauch- 

 stadt experiment station about the same results were obtained by early 

 ploughing as by a green manuring. In spring planting on all heavy soils, a 

 fall ploughing is the best precaution against unripe soils. 



Recently, letting the ground lie fallow'^ has again come into use for 

 heavy soils. In Hght soils it should be considered a wasteful process. The 

 benefit of letting ground lie fallow is its disintegrating action; no final de- 



1 Stoklasa, J., Ueber die Schicksale des Chilisalpeters im Boden etc. Blatter f. 

 Zuckerriibenbau 1904, No. 21. 



2 Koch, A., Bodenbakterien- und Stickstofffrage. Verb. d. Gesellsch. deutcher 

 Natur. zu Kerlsbad. 1903. Part I, p. 182. 



3 Vog-el, J., Die Assimilation des freien elementaren Stickstoffs durch Mikro- 

 crganismen. Centralbl. f. Bakteriol. II, 1905. Vol. XV, p. 174. 



* Treboux, O., Zur Stickstoffernahrung- der griinen Pflanzen. Ber. d. botan. 

 Gesellsch. 1905. p. 570. 



5 Hillmann, Bedeutung- der Agrikulturphysik etc. Nachrichten aus dem Klub 

 der Landwirte, 1902, No. 453 and Mitteil d. D. Landw.-Ges. 



