The Gardeners’ Chronicle Jan 24, 1891 p. 106-107

BURNT EARTH.

This material is very useful to the cultivator who has a cold or stiff soil to deal with, as it promotes the drainage, and is especially useful where liquid manure is applied, the noxious substances inimical to plant life being eliminated, and the soil made much warmer and richer in potash, lime, phosphoric acid, carbon, &c, ingredients which increase greatly the fertility of the land. Burnt earth dressing will prevent the cracking of the surface during dry weather, by rendering it less adhesive, and therefore not so liable to cake. We use a large quantity of it here for mixing in the Vine and Peach borders, for Roses, &c. under glass, and outside for herbaceous plants, and it is found to be useful for all of these; in fact, I have not the least doubt that it would prove beneficial to all kinds of plants here, and also wherever the soil is stiff and cold. If used in the proportion of one part burnt earth to six parts soil, and well mixed, it makes a great difference at once in the working of the latter, and is, in fact, the best thing that can be applied for the purpose; other materials that are often used for keeping soils open, such as sand, coal-ashes, lime rubbish, &c, do not give such good results, became they tend to impoverish instead of enriching the soil. A good instance of its utility is to be seen here at the present time; the borders are being renewed in our large Peach-house, because they were not properly made v. In n the house was built, and some four years ago I had a quantity of burnt earth worked in amongst the roots of the trees on the coldest side of the house. These trees now lift with a nice lot of fibrous roots; the soil comes away cleanly, and in good condition. The soil of the opposite border, which has not been treated in the same manner, has become sour in many places, and the tree-roots have not many fibrous roots.

I have not had the opportunity of trying its effects on light soils, but imagine that it would benefit them also if used in a smaller quantity; it would certainly improve any that might be overcharged with nitrogen through excessive manuring, &c., and during dry weather it acts as a reservoir for moisture when placed beneath the surface.

The best time of year for preparing it is during a spell of warm, dry weather, everything burning freely when dry, and earth being no exception to the rule; but it is possible to burn it under any circumstances by using a larger quantity of fuel.

In this, as in all other operations, very much depends upon getting a good start. We generally get some large tree-roots, or "butts," which have been sawn off, or some large lops cut into lengths of 3 to 4 feet, and a small quantity of sticks and straw to get a good body of fire ns quickly as possible. Toe small stuff soon burns out, but when the larger pieces get well alight, some bush prunings, &c., are thrown on it in order to keep the soil from settling down too close to the large logs, and as soon as the fire burns partly through this covering, some soil may be put on. This should be done gradually at first, so as not to overload the fire; but when all the heap has had one good covering of soil, and the fire is seen to be making its way through it, some coal-dust should be scattered all over, and another lot of soil put on; after this is burnt through, the heap should be ready to "draw" by opening out the middle, so as to spread the fire, and get a good base of ashes. This is best done by what is called a "muck drag" in this part—an iron tool with two or three prongs about 9 inches long, shaped like a Canterbury hoe; after the fire is well opened out, another old log should be put in the centre to keep a body of fire going on, some more garden refuse placed over this, and then more soil added.

The heap by this time should be a large one, and in dry weather will burn almost anything with little further assistance; but if the soil is wet and the weather rainy, some coal dust or old pieces of timber should be added occasionally so as to keep the fire well alight. The best soil for burning is a rather light loam from a pasture, cut in turves about 4 inches thick, but this is not easily obtained by many persons, and the best that can be had must therefore suffice; clayey soils will not do, as they burn too lumpy and require screening afterwards, and very sandy soils would most likely run down too fine to be of much benefit; old fruit borders that have got sour or worn out will answer well for burning, and refuse from the polling benches, if free from crocks, prunings of fruit trees, &c., make first-rate ashes if burned up in this manner, but this is properly speaking charred refuse, and does not come under the heading of burnt earth. W.H. Divers, Ketton Hall, Stamford.

The Gardeners’ Chronicle Jan 31, 1891 p. 150

BURNT EARTH.—The instructions given for preparing this on p. 106, leave little to be said in addition. Where wood is scarce, any combustible material at hand may be used, and a larger quantity of slack coal added; but I entirely differ from Mr. Divers when he says, that clay soils will not do for burning, as they are just the soils which derive the greatest advantage from it. Clays may differ, but the cold alluvial red clay of the new red sandstone formation on which I live is easily burnt, and immensely improved for gardening purposes by burning. When burnt, it closely resembles fragments of red brick, but if put upon the kiln, as it ought to be, in the driest season, and in thin layers, and thoroughly burnt, it becomes more porous and lighter than brick, and never reverts to condition of plastic mud. The advantages to plants grown in it are probably doe as much to mechanical as to chemical changes. It retains moisture in sufficient quantity, but not in excess, and allows roots to travel easily, and to branch in all directions evenly; but no doubt in many instances plants prefer their food cooked to raw, and find it more digestible. I am advised, for instance, that oxide of iron, which is largely present in this red clay, has its condition changed by burning, becoming a help instead of an impediment to plant growth. C. Wolley Dod.

The full value of this material it has yet to be realised, both by gardeners and farmers, and is difficult to say which of these would profit most by giving the subject the consideration it deserves, and by continuing its use and distribution, especially upon cold and clayey soils. To such soils as these, invariably defective in drainage, or rather, by the close adhesive nature of the soil, unable to allow rain-water to percolate quickly to lower levels, the ordinary cultivation methods being employed, the liberal use of burnt earth cannot be overestimated. This fact I learned some years ago, in a private garden of which I had the management. The condition of the soil may be inferred from the following facts:—When I took charge of this garden, it was the custom to dig the kitchen garden always with a bucket of water at hand, to dip the spade in now and then; indeed, this vessel of water was considered to be one of the requisites for the due performance of the work. Not only was such a proceeding irksome to those engaged who had the work to do, but it was unsatisfactory to me also, for unless the land was upturned in early autumn to get the benefit of the winter's frost, it was heavy labour to deal with it at all. The soil in question was in a large measure the output from a tunnel which ran beneath the garden, and was of a greasy nature, except perhaps in the height of summer. I found, however, that I was no worse than my neighbours, and therefore endeavoured as far as possible, to remedy the evil. Fortunately there was plenty of wood obtainable, and burning a portion of the soil at convenient times in the manner described by Mr. Divers at p. 106, the soil became much improved. The burning was generally carried out in the period from July to September, the material being kept dry till made use of. As a quarter of the kitchen garden was cleared, burnt earth was added in the following way:—A trench was taken out u for trenching, while, on the surface, some 3 or 4 inches of road sweepings were scattered, the burnt earth being wheeled on and left in heaps to be worked in on the top of the first spit, leaving the uppermost spit in as rough a state as possible for the time. In the winter, opportunity was taken of the frost to wheel on to the surface all the burnt refuse from the rubbish fires, which was kept dry till it reached the open quarters in the kitchen garden, adding all the spare leaf soil which fortunately existed in pint; in the wood. When the worst of the winter had passed, and the frost had done its part in crumbling the rough clods, the surface was brought into nice tilth by the use of a Canterbury hoe. In lest than two years I had entirely dispensed with the bucket of water at digging, a flat tinned fork being used instead of t spade; and by deep working of the soil, the burnt earth was distributed and porosity ensured. The crops were excellent, and not the least in importance was the comparative ease with which the soil was worked. A neighbour, whose kitchen garden was more extensive than in my case, treated the whole of his very similarly, so far as the trenching and adding the burnt earth was concerned, and, indeed, I owe to him this valuable lesson. The only point in which my experience appears to differ from Mr. Divers is where he says, "clayey soils will not do," &c.; but this was exactly the kind of soil I had to contend with. If burnt too hard, this sort of soil is similar to brickbats, and would be very troublesome to manage. In the garden of which I speak, there was a large collection of choice alpines, and the screenings of the burnt earth I used freely, both in the soil and also for draining the pots, the plants appearing to like it. In Gloucestershire large quantities of blue lias clay is burnt annually, though I am not aware that it is used for improving the land to any extent, though it undoubtedly would very materially, if only by improving the drainage of all retentive soils, and from large heaps 30 or 40 feet in diameter at the base a very large percentage of the interior is reduced to dust, and from this to the size of a hen's egg. In the burning process, after a good body of fire has been established of logs of wood, faggots, lump coal, and such-like, nothing is employed but what is locally known as "forest slack," which is scattered over the clay as it is added to the heap. J.

BURNT EARTH AND ALPINE PLANTS.—There are numbers of plants classed as alpines, which require about the same kind of cultural treatment. Now, most alpines grown in this country suffer more from the excessive moisture of our winters, and the alternating frosts and thaws, and the utmost that we can do for them is to afford them the moat suitable soil and drainage. Here is a list of a few alpines and other difficult plants, which scarcely grew at all in our heavy soil till we used burnt earth:— Acaena, Adonis vernalis, Epimedium alpinum, Gentiana, Gnaphalium leontopodium, Cyclamen hederifolium, Polemonium, Lychnis alpina, Linaria, Vinca acutiloba, Silene acaulis, &c. A sickly bed of Ranunculus seemed also to derive great benefit from a good dressing of burnt earth twice in a season. In using this material, I prefer the autumn season; and some of the kinds may be almost covered with it, for not only does it afford protection to them, but seems to preserve them from moisture. Dressings of burnt earth do not interfere with the usual pricking up of the soil, and, furthermore, it has always a neat and tidy appearance. I once tried an experiment with a few Francoa ramosa, with the result, that those plants which had this earth and those which had not were so marked, that they might have been taken for different varieties. G. B. Claydon, Holbeck’s Park.

The Gardeners’ Chronicle  9:179-180 (Feb. 7, 1891)

BURNT EARTH AND TOMATOS.—I consider this substance as a most valuable ingredient for mixing with heavy soils. I make a practise of collecting all prunings, old Chrysanthemum stools, potting-shed refuse, &c, adding almost any kind of soil, and burn in a similar way to that described by Mr. Divers. I have found it answer well for mixing with our ordinary soil for Tomatos. I used it last season for part of my Tomatos, and was so well pleased with the effect it had, I intend to use it largely this season. I had last season quite three times the weight of Tomatos from plants where free admixture of burnt earth was used to what I had from the same variety without it. I should like to know if Mr. Divers, or any of your correspondents, hare tried it for Tomatos, and with what results. S. G. Randall, Skegness.