514 



The Storage of Farmyard Mariiire 



and ending with the heaps of bullock manure stored for nine months, 

 in which the changes are at a maximum. Up to the end of the three 

 months period the rise in temperature, the loss of dry matter, and the 

 loss of ammonia all vary together, being at a minimum in the compact 

 heap of cow manure, and at a maximum in the loose bullock manure. 



The other nitrogen compounds do not follow in the same simple 

 way as the ammonia : the more complex nitrogen compounds show a less 

 regular gradation ; there is a gain in the compact cow manure heap, 

 no change in the loose heap, and losses in the bullock manure heaps, 

 but the losses are not proportionate to the loss of dry matter or 

 the temperature. The amides show no gradation at all, and suffer 

 practically no change. 



The results for the nine months seem to fall out of line, but in point 

 of fact there has arisen a great difference between the two heaps. The 

 temperature of the loose heap rose during the earlier period to 71° C. 

 at which its microorganic population must have been profoundly 

 altered. The compact heap, on the other hand, only rose to 51° C, 

 and much less change would be produced. In both cases a certain 

 amount of reinfection would undoubtedly take place, but it would 

 probably be limited to the outer layers : a sheltered manure heap 

 through which there is no drainage probably does not allow of easy 

 distribution of infecting organisms. The result is well seen from the 

 temperature curves (Fig. 1 upper portion) : after 53 days the. loose heap 

 keeps at a lower temperature than the compact heap, so that it finally 

 loses less dry matter. Taking the aggregate temperature instead of the 

 maximum the proportionality between temperature and dry matter 

 holds good over the whole period. But the change in nitrogen 

 compounds falls out of line. 



If, however, we take only the heaps that did not rise above 51°, 

 in which, therefore, the microorganic population has not been so drasti- 

 cally changed, then the changes in nitrogen compounds fall more closely 

 into line with those of dry matter. The comparison (omitting the 

 amides) now becomes : 



