FARMERS' REGISTER— THE FOOD OF PLANTS. 



499 



*' evoheJ: a dark colored liquid, of a slightly sour 

 "or bitter taste will liUcwi.se be (brmed; and if the 

 " process be sufl'ered to continue lor a time suffi- 

 "ciently long, nothing solid will remain, except 

 "earthy and saline matter, colored black by char- 

 "coal. The dark colored fluid formed in the fer- 

 " mentation always contains acetic acid: and when 

 " albumen or gluten exists in the vegetable sub- 

 " stance, it likewise contains volatile alkali. 



" In proportion as there is more of gluten, albu- 

 " men, or matters soluble in water in the vegeta- 

 " ble substances exposed to fermentation, so in 

 " proportion, all other circumstances being equal, 

 " will the process be more rapid. Pure woody fi- 

 " bre alone undergoes a change very slowly; but 

 " its texture is broken down, and it is easily re- 

 " solved into new elements, when mixed with 

 "substances more liable to change, containing 

 "oxygene and hydrogene. Volatile and fixed 

 " oils, resins and wax, are more susceptible ol 

 " change than woody fibre, when exposed to air 

 " and water; and even the most inflammable sub- 

 " stances, by the absorption of oxygene, become 

 "gradually soluble in water. 



" Animal matters in general are more liable to 

 "decompose than vegetable substances; oxygene 

 "is absorbed, and carbonic acid and ammonia 

 " formed in the process of their putrefaction. They 

 " produce l(£tid compound elastic fluids, and leave 

 " a residuum of salts and earth, mixed with carbo- 

 " naceous matter."* 



We are ignorant of the respective proportions 

 and value of these difi'erent gaseous products of 

 both vegetable and animal IL^rmentation and de- 

 composition, and which of them it is most im- 

 portant to arrest, and wluch we can best afford to 

 lose. But this is certainly known — that the final re- 

 sult of all the successive changes caused by the ler- 

 mentation of manures, is the conversion of all their 

 soluble and nutritious parts into different gases, 

 which, being aeriform and elastic fluids, immedi- 

 ately escape into the atmosphere, and are utterly 

 lost. In the above passage, all the valuable parts 

 of manures are distinctly traced to that end, ex- 

 cept the dark colored liquor which is formed and 

 flows from fermenting manure— and this is equal- 

 ly destined to the same final decomposition and 

 loss, if not previously saved by being put to use. 

 It might require the time and exi)ense of years. 

 to produce all the changes from fermentation in a 

 large bodj' of manure, and arrive at the final re- 

 sult, the destruction and loss of all its nutritious 

 and valuable parts: but whether the process is ra- 

 pid or slow, lermentation is always tending to 

 that end. These changes, the fiirmer may has- 

 ten, or moderate and retard — but he cannot possi- 

 bly prevent their taking place. His only choice is 

 either to use the products of fermentation as fast 

 as they become fit for the food of plants, or by 

 permitting them to assume an airy form, to let 

 them be lost entirely. To adoj:)t and practice the 

 former course would be the pedi?c1ion of manuring 

 — a state which we may aim to approach, but 

 never can reach, until chemistry shall be properly- 

 applied to agricultural investigation and improve- 

 ment. But though it may be impossible to use 

 manures so as to secure (i'om waste and destruc- 

 tion all the products of fermentation, still we may 

 gain much in that res])ect by properly considering 



* Agricultural Chemistry. 



and applying the instruction, limited and imper- 

 lect as it is, with which we have been furnished 

 by chemistry. Belbre, however, we can pursue 

 the investigation of what products of ferment- 

 ing manures we should endeavor to save, it will 

 be necessary to know what are serviceable as 

 the food of plants, which will now be considered, 

 before resuming the subject of the fermentation of 

 manures. 



Thz Food of Plants. 



The absurd doctrines which have been taught as 

 agricultural truths, are strongly exemj)lified in the 

 several opinioiis that have formerly prevailed as to 

 what constitutes the food of plants' By one class, 

 it was supposed to be waler — by another, air 

 onl}'- — and by TuU and his disciples, pulver'- 

 ized earth was believed to be the food of plants, 

 and that water, air, and manures only acted 

 mechanically in presenting that food to the roots. 

 Among scientific inquirers these opinions have 

 long been exploded, and it is noAV the received 

 opinion that the food of plants consis^^s of all the 

 vegetable and animal matters which are soluble 

 in water, and may be drawn up by the roots — and 

 such aeriform matters as are absorbed by the 

 leaves of growing vegetables. "Plants, says Da- 

 " vy, are found by analysis to consist principally 

 " of charcoal and aeriform matter. They give 

 " out by distillation volatile compounds, the ele- 

 " ments of which are pure air, inflammable air, 

 " coally matter, and azote, or that elastic substance 

 •' which forms a great part of the atmosphere, and 

 " which is incapable of supporting combustion. 

 " These elements they give eitlier by their leaves 

 "from the air, or by their roofs from the soil. All 

 "manures from organized substances contain the 

 "principles of vegetable matter, and during putre- 

 " faction, are rendered either soluble in w-ater, or 

 " aeriform — and in these states thicy are capable of 

 "being assimilated to the vegetable organs. No 

 " one principle affords the pabulum of vegetable 

 " life; it is neither charcoal, nor hydrogene, nor 

 "azote, nor oxygene alone; butallof them together 

 " in various states, and various combinations."* 

 Carbonic acid gas, which is present in small propor- 

 tion in all atmospheric air, and which is produced 

 by every kind of fermenting matter, is supposed 

 to be taken up largely by the roots of plants,! as 

 it undoubtedly is by their leaves — and from this 

 supply, is formed the carbon of plants, or that large 

 proportion of their substance that may be convert- 

 ed into charcoal. Water is also absorbed from 

 the atmosphere by the leaves of plants, and this 

 power which the bounty of nature has provided, 

 can be most exerted when the weather is dry and 

 hot, as the air then holds the greatest quantity of 

 water in solution. 



All putrescent matters then being composed of 

 the same {cw component parts that serve to c^sn- 

 stitute all growing plants, (carbon, oxygen, hydro- 

 gen, and sometimes nitrogen or azote,) it follows 

 that every particle of the former, as manure, may 

 serve as the food of plants. But the probability is, 

 that the roots of plants cannot efFectually take up 

 these elementary liodies after they have assumed 

 their gaseous form: and if no growing plants are 



*Agricultural Chemistry — Lee. I. 

 fLibrary of Useful Knowledge — on the Food of 

 Plants. 



