THE WHEAT CULTURIST: 228-231 (1868)
S. Edwards Todd

CHARCOAL DUST AS A FERTILIZER. (PDF)

Charcoal is composed almost entirely of pure carbon; and when small fragments are exposed to the influences of the weather, they undergo very little change during a long term of years. Still the roots of growing plants will lay hold of the small pieces of charcoal, and appropriate the substance contained in the coal to the growth and development of the stems, leaves, and seeds of grain, fruit, and vegetables.

Experienced chemists assure us, charcoal, and particularly charcoal dust, has the power of attracting and fixing large quantities of ammonia, a substance which enters largely into the formation of useful plants, and of retaining this fertilizing material when buried in the soil, until the fine fibres of the roots of growing plants require it for promoting their growth. Charcoal has the power of attracting and retaining other gaseous substances besides ammonia, which are highly beneficial to growing wheat plants, as well as grass, vines, trees, and shrubs.

Every observing farmer who has been accustomed to raise wheat cannot have failed to notice the luxuriant growth of cereal grain round about the places where charcoal has been burned, even more than thirty or forty years ago. The growing stems of wheat that are produced on such old charcoal-beds are seldom affected with rust; and besides this, the straw is always much stiffer than that which grows where there is not a dressing of charcoal. Before charcoal can promote the growth of plants of any kind, the particles must be thoroughly decomposed, and reduced to a liquid condition. For this reason, previous to the application of charcoal dust as a fertilizer to any kind of soil, the coal should be run through a mill that will reduce the small pieces to fine powder. And even when charcoal is thus finely comminuted by some mechanical means, the action of the fertilizing matter on vegetation will be very slow.

It is said that charcoal possesses the power of absorbing ninety times its own weight of ammoniacal gases. This fact suggests that charcoal dust, which may be procured in large quantities, at simply the expense of carting, in and around many of our populous cities, should be scattered in the stables of domestic animals, after having been ground very fine, where it will absorb large quantities of the choicest fertilizing material, which, if mingled with the soil, would impart a rich store of pabulum to the roots of growing crops. But whether a farmer would be warranted in purchasing charcoal, grinding it to powder, scattering it in his stables, and applying it the soil, is a question that can be decided satisfactorily, only by well-conducted experiments. The probability, however, is that it would not pay, for the reason that the decomposition of the fragments of the coal would be so exceedingly slow, from year to year, that the beneficial effect would not be a fair equivalent for the expense incurred. Where a farmer can procure charcoal dust for the carting, he can well afford to haul it two or more miles for the purpose of applying it to certain kinds of soil.

Where the soil is deep, mellow, vegetable, black loam, or muck, it would not pay to cart charcoal dust to apply as a fertilizer, because there is an abundance of carbonaceous material already in the soil. But where the soil consists chiefly of a sandy loam, a gravelly loam, or is a heavy soil of any character, it will pay to cart charcoal dust to mingle with stable manure, to be applied to the soil where cereal grain, in particular, or grass, or any other crops, are to be produced.

As to the proper quantity of charcoal dust to be applied to an acre, there is no rule for determining how much may be used with profit. There is no danger, however, of applying too much. The larger the quantity the better. On those soils where charcoal dust will not be of any advantage to growing crops, a bountiful dressing will exert no injurious influence. The larger the quantity spread around all kinds of fruit trees, the smoother and fairer the fruit will be.

In many fields where cereal grain is grown, the old coal-pit beds should be carted and spread on those parts of the field that are not rich in carbonaceous material. Charcoal dust, finely pulverized, is an excellent material to mingle with the soil where fruit trees of any kind are being transplanted. From five to ten bushels per tree would be a liberal dressing. For an immediate fertilizing effect on the growing crops of almost any kind of soil, it would be more satisfactory to reduce the coal to ashes, and sow what remains, broadcast over the field, while plants of grain or grass are young and tender, as wood ashes are an excellent material for grain and grass, trees and flowers, fruits and vegetables of all kinds.

R. Ranson, Ashtabula County, Ohio, writes, touching pulverized charcoal, as follows: "I tried another experiment in 1860. My lands are coarse or loose gravel of rather poor quality. I sowed an acre of winter wheat (the blue-stem) preparing my ground as follows:

"The field was sown with barley in the spring previous; yield small (eighteen bushels per acre). I turned in the stubble the last week in August, harrowed it over, then took about eighteen bushels charcoal crushed fine, and top-dressed a strip through the middle of the acre over about one-third of its length; I then sowed on my wheat broadcast and harrowed it over twice. The result was, the heads when ripe were at least twice as long as where no coal was put on. I harvested all together; the yield was forty-three bushels. I think by applying about fifty bushels of coal to the acre as a top-dressing, made fine by grinding in a common bark mill, it would increase the yield at least four hundred per cent., if the soil is poor.

"He further states he used burned clay and ashes in the fall of 1860, at the rate of about one hundred bushels of burned clay, taken from a fallow where timber had been uprooted several years by heavy winds. The soil on which the timber grew was burned together with the old roots and clay entwined, and perhaps some muck; the whole, ashes, clay and muck, after being burned as above, were hauled off’ in a wagon and put upon the wheat field as a top-dressing, and harrowed in with the wheat. The land was poor quality of gravel; the yield was about five hundred per cent, over the remainder of the field where no clay was put. I think there is no fertilizer ahead of this as a top-dresser." See Mixing Soils, second volume of Young Farmer’s Manual.