The Working Farmer 3(5): 111-112 (July 1, 1851)

We are glad to be endorsed by Prof. Playfair in our oft-made assertions in favor of charcoal as a manure. Its use with guano renders the latter of nearly double value, while its application to clayey soils does away with the adhesiveness so objectionable in such soils.—[ED.

Charcoal is an impure form of carbon, and is manufactured on a large scale for the purpose of the art. The process of manufacture consists in exposing to heat billets of wood or other organic matter, under such conditions as either wholly or partially to exclude the air. Charcoal has several properties which render it of value to the cultivator. As a manure, it does not act by furnishing carbon to the vegetation; because it is in reality, one of the most indestructible substances known, and remains for an indefinite length of time without change. But it is remarkably absorptive of certain gases, which it retains within its pores in a state of high condensation. A fragment of freshly burned charcoal condenses as much as ninety times its bulk of ammoniacal gas, and thirty-five times its volume of carbonic acid. As these two gases form the principal organic food of plants, it is obvious that charcoal may have a powerful individual action upon their growth. The experiments of Saussure and others have shown that plants flourish with great luxuriance when the atmosphere in which they grow contains more than the usual amount of carbonic acid. Charcoal, after having absorbed carbonic acid and ammonia from the air, places plants under favorable conditions for receiving and appropriating a larger than usual amount of this organic food. The only difference is, that, instead of entering the plant by the leaves, they reach it through the roots, which absorb the rain water containing these gases, washed out from the charcoal. Thus, charcoal, from its absorptive nature, becomes an indirect means of increasing the supply of carbonic and nitrogen to plants. Different kinds of charcoal have varying values in this respect. Experiments made by exposing freshly burned pieces of charcoal to the air, showed their different absorptive powers, by the increase in weight after they had been exposed a week to the atmosphere. The charcoal from fir gained 13 per cent, in weight; that from lignum vitae, 9.6; that from box, 14; from beech, 16.3; from oak, 16.5; and from mahogany, 18. Charcoal also possesses the property of absorbing and retaining the odoriferous and coloring principles of most organic substances. It is, on this account, used for removing the putrefactive taint from foul water or other putrid substances. Wher used as a filter for foul water, both the smell and color are removed. From this deodorizing property charcoal is frequently mixed with nightsoil, and other decaying manures, which it keeps free from smell, and at the same time aids in preserving, by absorbing the gases which would otherwise escape. A mixture of charcoal and burnt clay is frequently used for this purpose with excellent effect. Charcoal, when employed as a manure, acts, to a small extent, by presenting, in a soluble form, the ashes of the wood from which it was prepared; but this action is only temporary, and of small importance, when compared with its principal point of utility, viz., its power of absorbing from the air the gaseous food of plants, and, therefore, of presenting it in a more condensed form, and in greater quantity.— Prof. Playfair, in Morton's Cyclopedia of Ag.