552 



The Storage of Farmyard Manure 



Table VII. Changes in nitrogen compounds in manure heaps, horse 

 dung, Rothamsted, showing gains of complex nitrogen compounds 

 and loss of ammonia. 



In the open 



Loose heap on soil 



Loose heap on concrete 



At start At end 

 (Jan. 23, (April 30, 



Manure in heap 

 Dry matter 

 Ammoniacal nitrogen 

 Amide nitrogen 

 Other nitrogen 

 Total nitrogen 



1914) 

 1016 

 254 

 0-98 

 0-41 

 319 

 4-58 



1914) 



741 



183 

 0-10 

 0-44 

 3-65 

 419 



Per- 

 centage 

 change 



-271 



-28-0 

 -19-2 

 + 0-7* 

 + 10-0* 

 - 8-5 



At start At end 

 (Jan. 23, (April 30, Percentage 



1914) 



508 



128 

 0-49 

 019 

 1-52 

 2-20 



1914) 



451 

 90 

 0-06 

 0-21 

 1-72 

 1-99 



change 

 -11-2 

 -29-7 

 -19-5 

 + 0-9* 

 + 9-1* 

 - 9-5 



* Gains. 



Apart from this special case of pure horse manure we find no evidence 

 that the complex nitrogen compounds tend to increase at the expense 

 of the ammonia in the manure heap. The action is quite possible, 

 indeed it is brought about in the laboratory experiments, but the 

 conditions of the heap do not seem to favour it. We cannot help 

 thinking that there is some mistake in Maercker and Schneidewind's 

 figures, and we are strengthened in this view by the circumstance that 

 no other investigator of repute has, so far as we know, obtained anything 

 like such high results. 



Summary of results, and application to the storage of manure. 



We can now bring together the various results obtained during the 

 course of our investigations. 



We find that the changes are at a minimum under anaerobic con- 

 ditions, and they are as follows: 



1. In the laboratory experiments as much as 17 % of the dry matter 

 may be converted into gas : in the heap the proportion is less. 



2. The non-nitrogenous constituents are particularly affected, as 

 much as one quarter of the pentosans may disappear during the process 

 and other constituents break down in like proportion. The gas evolved 

 contains carbon dioxide, marsh gas, and hydrogen. 



3. In the laboratory experiments the nitrogenous compounds 

 also break down, part of the complex compounds giving rise to ammonia. 

 More ammonia is found at 26° C. than at 15° C. 



4. No nitrates are formed. 



