No. 3. 



On the Preparation and Use of Manures. 



91 



leaves of plants ; or, as some agricultural 

 chemists with good reason suppose, is under 

 certain circumstances dissolved, or is solu- 

 ble, and thus rendered fit for immediate nou- 

 rishment to plants, it must be considered the 

 most important item in the production of 

 manures. The salts, which are the most 

 efficient in aiding vegetation, or the most 

 active manures, are those formed from the 

 alkalies and their various combinations. 

 Thus, from pure lime or calcium, is formed, 

 by the union with carbonic acid, carbonate 

 of lime ; with phosphoric acid, phosphate of 

 lime, the base of bones, one of the most effi- 

 cient of fertilizers; with sulphuric acid, sul- 

 phate of lime, or gypsum, the value of which 

 is well understood; and so with the other 

 alkalies, which, in their combinations, form 

 substances of the utmost consequence to 

 plants. It is well known tliat the outer co- 

 vering of some kinds of cane, contain so 

 much flint or silex, as to strike fire with 

 steel ; and some of the grasses contain this 

 substance in such quantity that their ashes 

 will melt into glass with potash. Now, this 

 hardness, so necessary to their perfection, 

 could not be attained unless this flint had 

 been rendered soluble by union with an al- 

 kali, forming a silicate of potash, and by 

 this solubility been rendered fit for the ac- 

 tion and appropriation of the plant. 



Food of plants. — If we would know what 

 kind of food is required by plants, one of the 

 first steps necessary, is to ascertain of what 

 the plants themselves are composed. The 

 combinations of matter may be said to be 

 absolutely endless; but the original elements 

 of this multitude of combinations, are few 

 in number. Chemistry has detected only 

 some fifty-five substances incapable of fur- 

 ther reduction, or what are called simple 

 substances ; and of these, strange as it may 

 appear, only four, except in proportions 

 merely accidental, go to the formation of 

 plants. Of these the first is Carbon. This 

 forms from 40 to 50 per cent, by weight, of 

 the plants cultivated for food ; and is there- 

 fore most important to animals and to man. 

 The second of these simple substances, is 

 Oxygen. The quantities of this substance 

 are immense; and though we are acquainted 

 with it only in the form in which it exists in 

 the air, nearly one half of the solid crust of 

 the globe, 21 per cent, of the atmosphere, 

 eight pounds in every nine of water, and 

 more than one half of the living bodies of 

 all plants and animals, are oxygen. Hydro- 

 gen is the third substance peculiar to plants. 

 This is the lightest of known substances, 

 and forms a small part of the weight of all 

 animal and vegetable bodies; constitutes 

 one-ninth part of the weight of water, but 



enters into the composition of none of the 

 masses that go to form the crust of the 

 globe, coal excepted. The fourth simple 

 substance, entering into the formation of 

 plants, is Nitrogen. This forms 79 per 

 per cent, of the bulk of the atmosphere, 

 constitutes part of most animal and some 

 vegetable substances; is found in coal to the 

 amount of one or two per cent., but does not 

 exist in any other of the mineral masses 

 constituting the crust of the globe. Al- 

 though not an abundant substance, the im- 

 portance of it is not the less decided, and 

 some of its functions are of the most indis- 

 pensable kind. Plants then, are composed 

 of carbon, oxygen, hydrogen, and nitrogen ; 

 the first derived from carbonic acid, the se- 

 cond from the atmosphere, the third from 

 the decomposition of water, and the fourth 

 from ammonia absorbed by water, and taken 

 up by the roots of the vegetables. Some of 

 the earths are occasionally detected in plants, 

 and salts of some kind are always present. 

 In the preparation of manures, the principal 

 object to be aimed at, it is evident, must be 

 to supply the materials needed to furnish 

 the carbon and the ammonia ; and these are 

 found in the greatest abundance in dead, or 

 decomposed animal and vegetable matter. 



Law of Nxitrition. — It seems to be a law 

 of nature, that the higher the grade of the 

 animal, or the more complicated its organ- 

 ization, the greater the necessity of a cor- 

 responding degree of organization in the 

 substances used as food : indeed the manner 

 in which the crude materials, found in the 

 earth and atmosphere, are worked up by 

 plants into a state suitable for conversion 

 into the flesh of animals or food for man, 

 exhibits the strongest proofs of benevolent 

 design in the formation of such grades of 

 organized matter. Man can, indeed, live 

 on plants, but his teeth demonstrate that 

 flesh was to constitute no inconsiderable 

 portion of his food. As all animals receive 

 their food, either directly or indirectly, from 

 the vegetable kingdom, it is evident their 

 excrements, or their decomposed bodies, 

 must form manures of the most valuable 

 kind; and it is to this source, the excre- 

 ments of animals, that the farmer must look 

 for his supply of manures to restore the fer- 

 tility of the soil. In treating further of ma- 

 nures, it will be best to begin with this, as 

 the most important class. 



Animal manures. — A late British writer 

 on agriculture, says: "The chief use of cat- 

 tle on an arable farm, besides those neces- 

 sary for the operations of husbandry, is to 

 produce manure for the land. If the cattle 

 repay their food, and the expense and risk 

 attending their keep, the manure is suffi- 



