6 A PRACTICAL TREATISE 



convey instruction by abstruse disquisitions or fine-spun theo- 

 ries, respecting the food of plants, or the manner in which 

 they are nourished ; but we think that a few remarks on the 

 nature and properties of manure may properly precede the 

 practical details of its application to the soil, and will not be 

 unfavorably received even by men whose superior experience 

 does not seem to need such information. 



Distinction of Manures. —Cultivation consists of two dis- 

 tinct objects, of which one comprehends the mechanical labor 

 bestowed upon the soil, and the other is composed of the 

 chemical application of manures, which either directly com- 

 municate the nutriment which they convey to plants, or which 

 assist vegetation by promoting the active powers of the soil, 

 and of those substances with which it may be combined. It 

 is well known that, when plants are continually reaped from 

 off the land, the soil in time becomes exhausted, and then it 

 becomes necessary to restore the waste which has taken place 

 by a supply of matter either affording direct nourishment or 

 stimulating the power of the soil. These substances, being 

 mixed with the ground by the action of the plough, are termed 

 manure. 



All vegetable and animal substances which become decom- 

 posed, or putrid, contain the necessary elements for the repro- 

 duction of the plants which we cultivate, provided they be 

 duly mixed in just proportions with the soil, and that they be 

 reduced to no more than a certain degree of putrefaction, by 

 which they can be applied to the land in a beneficial state as 

 manure. It is for the most part composed of straw which has 

 served as litter to animals, and which, being impregnated witli 

 their dung and urine, and thrown into heaps, is thus suffered 

 to heat, ferment, and rot. The mould produced by the decom- 

 position of vegetables appears, however, to act more slowly, 

 but yet more durably, as the aliment of plants, than that 

 which has been produced by passing through the bodies of 

 animals, which latter not only operates more promptly as 

 i.ourishment, but also acts directly upon the sap, to the mani- 

 fest vigour of their growth. The great object of these ma- 

 nures should be to make them afford as much soluble matter 

 as possible to the roots of the plant, and that in a gradual 

 manner, so that it may be entirely consumed in forming the 

 sap. Those substances which in their nature partake of 

 mucilaginous, gelatinous, or saccharine matter, of oily and 

 extractive fluids, and of solutions of carbonic acid in water, all 



