544 The Storage of Farmiyard Manure 



was discovered by Gayon and Dupetit^ at Nancy, and studied in 

 Germany by Stutzer^. 



ImmendorF, on the other hand, favoured an oxidation hypothesis, 

 and considered that evolution of nitrogen took place in presence of 

 oxygen, and was the result of direct oxidation or combustion of the 

 nitrogen compounds to gaseous nitrogen. No reduction of nitrate was 

 assumed. PfeifEer and his assistants at Jena* began on the reduction 

 hypothesis and supposed that nitrates were formed on the outside of 

 the heap, and then diffused inside, where they were denitrified. But 

 during the course of their experiments they were led to change their 

 view, and they ended by accepting the oxidation hypothesis. As their 

 results are typical of much that has been done they may be noticed 

 in some detail. In the first series of experiments two lots of cow manure 

 (made with peat moss litter) were put up : air was blown through one, 

 and over the other. The losses of nitrogen were : 



They argue that blowing air over the dung would be favourable to 

 a nitrification and denitrification process, while blowing air through 

 would be wwfavourable to denitrification, since this requires an absence 

 of air. Yet it causes greater loss. 



They also showed that loss of nitrogen went on in experiments 

 where nitrification was not observed, and further that the effect of 

 antiseptics on the extent of the loss was not what might be expected 

 from a knowledge of their effect on denitrifying organisms. These last 

 two considerations are in the nature of negative arguments and would 

 not in themselves prove much. The first argument, — that loss is 

 increased, and not diminished, by blowing air through the manure 

 instead of over it, — is more positive, but unfortunately it was found 

 later on to be unsound, for the authors showed that denitrification took 

 place in their apparatus* just as rapidly when air was blowing through 

 as when it was excluded. They realised that they had not well estab- 

 lished the case against denitrification, but they still thought that the 



^ Com'ptes Rendus, 1882, 95, 644—46, and 1365-67 : also Memoires de la Soc. des Sciences 

 physiques et naturelles de Bordeaux, 1886, Series m. Vol. ii. 



2 Journ. f. Landw. 1894, p. 383. * Lundw. Jahresbikher, 21, 317. 



* Th. Pfeiffer, E. Franke, C. Gotze, H. Thurmann, "Beitrage zur Frage iiber die bei 

 der Faulnis stickstoffhaltiger organischer Substanzen eintretenden Umsetzungen," Landw. 

 Versuchs-Stat. 1897, 48, 189-245. 



