62 THE CHEMISTRY OF THE FARM 



power of retaining ammonia. Sprinkling powdered 

 gypsum, superphosphate, or kainite on the fresh 

 manure also greatly diminishes the loss of ammonia. 



Farmyard manure readily undergoes decomposition : 

 this decomposition proceeds quite differently according 

 as air is admitted or excluded. If the manure is 

 thrown loosely in a heap it becomes very hot, and 

 rapidly wastes ; the organic matter is in this case 

 virtually burnt, and yields carbonic acid, water and 

 ammonia ; the work is performed by aerobic organ- 

 isms.-^ If, on the other hand, the manure is consoli- 

 dated and kept thoroughly moist, so that air is 

 excluded, the mass ferments with but little rise in- 

 temperature, carbonic acid and methane (CH^), with 

 some hydrogen and nitrogen, are given off, the loss of 

 weight is far less than in the previous case, and the 

 litter is chiefly converted into humic matter. This 

 fermentation is the work of anaerobic organisms.^ 



The ammonia present in fresh manure gradually 

 disappears, it apparently combines with the humic 

 matter arising from the decomposition of the litter, 

 an amide being produced. 



It is sometimes best to cart the fresh manure on to 

 the land and at once plough it in ; the losses in the 

 heap are thus prevented, and a greater bulk of manure 

 added to the soil ; heavy land is especially benefited by 

 such treatment. When the manure must be kept, it 

 should be made without delay into a solid heap, which 

 must not be allowed to get dry. A manure pit under 

 cover may be provided with a pump by which drainage 



* Aerobic organisms (fungi and some bacteria) require oxygen for 

 the performance of their work. Anaerobic organisms (yeasts and 

 Bonie bacteria) decompose organic matter without consumiBg oxygao. 



