W4v 



Stable Manures, Composts, 

 and Green Manures 



Nature of Stable Manures 



A large part of the plant residues removed from the land in the 

 form of harvested crops is returned to the soil as various waste 

 materials, ranging from factory to kitchen and farm wastes, or after 

 the plant residues have been used for bedding purposes and been 

 partly consumed by animals, or after they have passed through the 

 digestive system of these animals. 



Stable manures consist of three groups of components: (a) bed- 

 ding or litter, (b) solid excreta of animals, (c) liquid excreta or 

 urine. The nature and relative concentration of these components 

 vary greatly in different manures, depending on the animals and the 

 methods of feeding and handling the animals. Since the various 

 components of the manures also differ considerably in chemical 

 composition, it is natural to expect that the composition of different 

 manures should vary. 



Plant residues used for bedding purposes are usually high in car- 

 bohydrates, especially in cellulose, and low in nitrogen and minerals. 

 Urine is high in nitrogen and minerals and has very little, if any, 

 carbohydrate material. Solid excreta contain considerable amounts 

 of proteins, and thus tend to give a more balanced medium for the 

 growth of microorganisms. The chemical composition of three 

 diflFerent types of stable manures is shown in Table 65, Sheep 

 manure is high in protein, in cold-water-soluble organic materials, 

 and in ash; it is low in cellulose. Horse manure is low in protein 

 and high in cellulose and hemicelluloses. Cow manure falls be- 

 tween these two. A comparison of the nitrogen and mineral compo- 

 sition of a number of manures is given in Table 66. Chicken and 

 pigeon manures are highest in nitrogen, phosphorus, and potassium, 



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