Charcoal

from 1846 edition of Southern Planter

We make the following extracts from a long communication addressed to the Farmer’s Cabinet:

Upon the subject of charcoal possessing the power of condensing ammonia, permit me to give a few quotations from Dr. Liebig’s great work on Agricultural Chemistry; speaking of the property of clayey soils and soils that contain iron, of absorbing ammonia, he says: “Soils therefore which contain oxides of iron and burned clay, must absorb ammonia, an action which is favored by their porous condition; they further prevent the escape of the ammonia once absorbed by their chemical properties.” “The ammonia absorbed by the clay or ferruginous oxides is separated by every shower of rain, and conveyed in solution to the soil. Powdered charcoal possesses a similar action, but surpasses all other substances in the power which it possesses of condensing ammonia within its pores, particularly when it has been previously heated to redness. Charcoal absorbs ninety times its volume of ammoniacal gas, which may be again separated by simply moistening it with water.” De Saussure.

In another place, while speaking of the source of carbon and nitrogen, he says, “It must not, however, be left unmentioned, that common wood charcoal, by virtue of its ordinary well known properties, can completely replace vegetable mould or humus.” “Plants thrive in powdered charcoal and may be brought to blossom and bear fruit, if exposed to the influence of the rain and the atmosphere.” “Charcoal is the most indifferent and most unchangeable substance known; it may be kept for centuries without change, and is therefore not subject to decomposition. The only substances which it can yield to plants, are some salts which it contains, amongst which is silicate of potash. It is known, however, to possess the power of condensing gases within its pores, and particularly carbonic acid. And it is by virtue of this power that the roots of plants are supplied in charcoal exactly as in humus, with an atmosphere of carbonic acid and air, which is renewed as quickly as it is abstracted.”

An important consideration here presents itself; this highly valuable substance – charcoal – “may be kept for centuries without change, and is therefore not subject to decomposition.” Soils, therefore, once well supplied with this article, will never again need an application, unless that supply has been removed from them by some unusual means. This is a gratifying circumstance, for though it may be somewhat expensive at first to get it, and place it in the soil, we have reason to think we will never have it to do over again.

Liebig also says; “Charcoal in a state of powder, must be considered a powerful means of promoting the growth of plants on heavy soils, and particularly on such as consist of argillaceous earth.”

Care should be taken that the charcoal be well pulverized, for it has been ascertained that during the process of burning the wood to get it, the openings of the pores become closed by a vitreous matter – probably caused by the fire melting the silicate of potash – and thus deprive it of the power of absorbing gases. By crushing it other openings are made, which unless the charcoal is again subjected to fire, will not become closed.