542 The Storage of Farmyard Manure 



These results clear up a problem that has caused considerable con- 

 troversy in the past. Many observers found nitrate in the manure 

 heaps, while others have failed to do so. Probably some of the supposed 

 nitrate was simply an error in manipulation, especially where reduction 

 methods only were employed, but in many cases the result was un- 

 doubtedly sound. But some of the negative results were equally 

 sound. Sometimes the discrepancy has been attributed to age, some- 

 times to other factors, but we believe that those who found nitrate 

 were dealing with the dry outside of the heap, while those who did not 

 were dealing with the moist inside or with a mixed sample of the whole 

 heap, — outside and inside. Now the nitrate of the outer crust rapidly 

 disappears in contact with moist manure, so that a sample drawn in 

 the ordinary way to represent the heap soon contains little if any 

 nitrate, even if some was originally present. Whether the dryness 

 necessary for the accumulation of nitrate is required simply to protect 

 it against denitrification, or whether it is needed by the nitrifying 

 organisms to insulate them from their neighbours or their neighbours' 

 products, or whether other causes operate, are questions for further 

 investigation. 



On the cause of the evolution of nitrogen during the 

 decomposition of manure. 



Earlier work. 



It has long been known that losses of nitrogen occurred during 

 bacterial decomposition of organic matter which could not be attributed 

 to the volatilisation of ammonia, and which were put down to an 

 evolution of gaseous nitrogen. 



The first records we have been able to find go back to the time 

 when the sources of nitrogen for vegetation were being investigated, 

 and attempts were made to set up a balance sheet showing the relation 

 between the amounts of nitrogen in the plant and the soil at the 

 beginning and at the end of the experiment. Reiset^, Ville^, and 

 Boussingault^, who were first to make these experiments, sometimes 

 found less nitrogen in soil + plant at the end of an experiment than 

 in soil + seed at the beginning, and attributed the difference to an 

 evolution of free nitrogen. Some of these early observations were 



^ Reiset, Jahresbericht der Chemie, 1856. 

 ^ Ville, Recherches Expdrimentales sur la Vegetation, 1857. 



^ Bonssingault, Ann. de Chim. et de Phys. (iii.) 46, 185G, cand Compt. Re7id. 1858,47 

 (see his collected works). 



