504 The Storcuje of Farmyard Manure 



Experimental Stations to take the matter up, and find out the cause 

 of the loss and if possible some means of preventing it. 



These experiments are discussed later on : the general conclusion 

 as to the cause of the loss was that it might arise from the evolution 

 either of ammonia or of gaseous nitrogen. Numerous experiments 

 by many workers showed that the evolution of ammonia was only 

 slight except when the heap was actually hot and giving off vapours : 

 usually the outside layers of the heap retained it. The loss was there- 

 fore attributed mainly to gaseous nitrogen. 



The efforts to stop the loss met with no success. Schattenmann^, 

 a large horsekeeper in Bauchsweiler, Alsace, managed enormous heaps 

 of horse manure extremely well and he added either sulphate 

 of iron or gypsum. The idea gradually developed that gypsum 

 "fixed" the ammonia and prevented loss. As this seemed promising 

 Joulie^ tried a number of likely "fixers," but found them ineffective. 

 Similar negative results were obtained by Aeby and others^, and by 

 Pfeiffer^ in the experiments organised by the German Agricultural 

 Society. There is no evidence that any "fixer" is of any use. 



Another application of Boussingault's principle led to results which 

 are probably considerably exaggerated. Maercker and Schneidewind^ 

 found that the amount of quick acting nitrogen in the manure (i.e. 

 ammonia and amide), is considerably less than the digestible nitrogen 

 in the food, while the nitrogen in the form of complex nitrogen com- 

 pounds is considerably more than corresponds wuth the indigestible 

 nitrogen in the food. Later investigations have shown that some 

 conversion of ammonia into complex nitrogen compounds may take 

 place, though it is doubtful whether in normal circumstances it attains 

 the high value given by Maercker and Schneidewind. 



The changes observed in the manure heap. 



We shall begin the account of our investigations by describing the 

 changes that we actually found in manure heaps stored under known 

 conditions, and shall then proceed to deal with the experiments designed 

 to elucidate the reactions by which they are produced. As the changes 



^ Schattenmann, Annalea Chun. Phys. Series 3, vol. iv. p. 358. The work is also 

 quoted in Boussingault's Economic Rurale, 2nd edition, vol. i. p. 701. 



2 Anjiales Agronomiquea, 1884, 10, 289-301. 



3 Landw. V crsuchs-Slat. 1897, 48, 247-360. 



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



* Landw. Jahrbucher, 1898, p. 215. 



