528 The Storage of Farm/yard Manure 



The eeactions taking place in the heap. 



II. The d&co»ipositio7i of farmyard manure under carefully controlled 

 conditions in the laboratory. 



We have just seen that the bacterial decomposition of protein in 

 the laboratory involves the formation first of amino-acids and then of 

 ammonia. This reaction proceeds under both aerobic and anaerobic 

 conditions, but in the latter case amines are formed as well. The 

 complex nitrogen compounds of sewage (which are presumably of the 

 same nature as protein, or contain the protein groupings) also decom- 

 pose under anaerobic conditions to yield ammonia and presumably 

 amines: we may suppose therefore that the reaction is similar to 

 the above, and that amino-acids are formed as intermediate products. 



Under aerobic conditions the same reaction apparently goes on, 

 but it proceeds further and gives rise to a certain amount of nitrate. 

 But a new reaction also sets in whereby some nitrogen is liberated. 



Thus, the sewage decompositions seem to be entirely on a par with 

 the bacterial decomposition of protein. But the decompositions in the 

 manure heap do not : there is, for example, no accumulation of ammonia 

 or anything to indicate that the complex nitrogen compounds break 

 down through the ammonia stage at all. It is true that the end products 

 are the same as in the aerobic stage of sewage decomposition, indicating 

 that the reactions may be the same also, but the parallel cannot be 

 pressed too far until it is known whether decomposition under strictly 

 anaerobic conditions would also resemble that of sewage. However 

 well the manure heap is compacted we have never found proof that 

 this was the case. 



As it is difficult to control the conditions in a manure heap we 

 carried out the next set of experiments in the laboratory. The manure 

 was put up in bottles or jars and sealed down tightly for the anaerobic 

 experiments, or exposed to a curent of washed and purified air for 

 the aerobic experiments, acid traps being provided to retain any ammonia 

 carried over. The aerobic and anaerobic experiments were made side 

 by side to allow of a strict comparison of the results, but it will be con- 

 venient to describe them separately. 



Anaerobic storage. The results obtained under anaerobic conditions 

 are set out in Table IV and Fig. 7. 



In all cases there is a breaking down of some of the complex nitrogen 

 compounds. , 



