AND RURAL ECONOMIST. 



175 



attract and retain the food of plants from air and water, as 

 well as afford a proper medium to prepare and communicate 

 the principle of fertility. 



Every species of matter capable of promoting the growth 

 of vegetables may be considered as manure. Vegetables are 

 composed of certain substances called by chemists oxygen, 

 [formerly called vital air] hydrogen, [inflammable air] car- 

 bon, [coaly matter] and nitrogen, or azote, one of the con- 

 stituent parts of the atmosphere. The substances employed 

 as manure should be composed of all or some of these ele- 

 ments. 



Vegetable and animal substances, deposited in the soil, are 

 consumed during the process of vegetation ; being mostly 

 absorbed by the roots of plants, combined with water. These 

 substances compose what is called the food of plants. This 

 food is mostly taken in by the roots, which are analogous to 

 the mouths of animals, but some portion of the nourishment 

 of vegetables is also derived from the atmosphere, imbibed 

 by the leaves and bark. Thus the carcasses of lambs and 

 other small animals are sometimes hung on the limbs of fruit- 

 trees to promote their growth, and cause them to bear abun- 

 dantly, and thus produce some effect ; but the practice is 

 slovenly and wasteful, as the air is contaminated, and the 

 carcass buried near the roots would be much more efficient 

 as manure. 



A controversy has existed relative to the degree of fer- 

 mentation which manure should undergo before it is applied 

 to the soil. Some agriculturists contend that long, fresh, or 

 unfermented manure is to be preferred. Others assert that 

 stable and barn-yard manure never should be spread in the 

 field till the fibrous texture of the vegetable matter is entire- 

 ly broken down, and it becomes perfectly cold, and so soft as 

 to be easily cut with a spade. 



Sir Humphrey Davy observes, ' If the pure dung of cattle 

 is to be used as manure, there seems no reason why it should 

 be made to ferment, except in the soil; or if suffered to fer- 

 ment it should be only in a very slight degree. The grass 

 in the neighborhood of recently voided dung is always coarse 

 and dark green ; some persons have attributed this to a nox- 

 ious quality in unfermented dung ; but it seems to be rather 

 the result of an excess of food furnished to the plants. 



' During the violent fermentation which is necessary for 

 reducing farm-yard manure to the state of what is called 

 short muck^ not only a large quantity of fluid, but likewise of 



