NUTRITIVE MANURES. 51 



on gradually in the earth, and thus furnishes vegetation 

 with its necessary aliments for a long time. 



The excrements of animals, formed by the digestion of 

 their food, have already undergone a decomposition which 

 has disorganized the principles of their aliments, and in a 

 greater or less degree changed their nature. The strength 

 of the digestive organs, which varies in each species of 

 animal, the difference of food, and the mixture of the di- 

 gestive fluids furnished by the stomach, modify these ma- 

 nures to a very considerable extent. 



The excrements of some animals, as of pigeons, fowls, 

 &/C., are employed without undergoing any new fermenta- 

 tion, because they consist mostly of salts, and contain but 

 few juices. Fields are often manured with the excre- 

 ments of sheep, collected in the sheep-folds, or scattered, 

 as in parks, by the animals themselves upon the soil ; but 

 in general the dung of horses and of horned cattle is made 

 to undergo a new fermentation before being applied as 

 manure. 



The most general method of producing the fermenta- 

 tion of the dung of quadrupeds, is, in the first place, to 

 form upon the ground of sheep-folds and stables a bed of 

 straw or dry leaves. This bed is covered with the solid 

 excrements of the quadrupeds, and impregnated with their 

 urine. At the end of fifteen days or a month, it is carried 

 to a place suited for fermentation, and there formed anew, 

 care being taken every day to spread upon it litter and 

 the scatterings of the racks. The formation of these 

 beds, contributes much to the healthfulness of the stables 

 and to the cleanliness of the animals. When, from a 

 scarcity of straw, the beds cannot be made of sufficient 

 thickness, or renewed often enough, a layer may be 

 formed of lime or gravel, broken fine and covered with 

 straw. These earths will imbibe the urine, and when 

 they are penetrated by it may be carried into the fields to 

 be buried in the soil. The nature of the earth, upon 

 which beds are formed in sheep-folds or stables, should 

 vary according to the character of the soil which is to 

 receive them, because, by attention to this, the soil may 

 be improved as well as manured. For argillaceous and 

 compact earths, the layers should be formed of gravel 

 and the remains of old lime mortars ; whilst those of fat 

 marl or of clayey mud should be reserved for light and 

 dry soils. 



