compest dung was laid on along with the gypsum, but where no compost was applied, the gypsum by itself was of no avail;' and in some other trials made in this country, when laid upon alternate lands of oats and turnips, it has produced no visible effect *. In his other experiments on potatoes and onions, as also on carrots and cabbages, and on various crops of white corn, no perceptible difference could be observed in the application of gypsum; except that, in one instance, the plastered rows of potatoes were rather worse than the others;' and that, on old land newly ploughed up, but not pared and burnt, the gypsum was found to act as a corrector of the soil, and thus to give more grain and less straw.' Mr. Parkinson, indeed, attributes its chief powers to consist in its quickly cementing, and thus preventing the heat of the sun from exhaling the moisture or nutritious quality of the manure; by which means the plant, being kept moist at the root, consequently grows well, and quickly gets a shade from its own sprouts t. This would, however, tend to prove that its application would be serviceable to all crops in dry weather: an opinion which is not borne out by what has been already stated of its effects. Such are the chief points regarding its practical application to which some objections have been made. 1st. As tending to render the land stiff under the plough. 2nd. As exhausting the soil by forcing vegetation. 3rd. As being confined in its effects to particular crops, and becoming, perhaps, prejudicial when those are followed by others of a different nature. To which it may be answered: 1. That the increased tenacity of the soil can only be occasioned either by some extraordinary excess in the application of the gypsum, or by its being laid upon heavy clay, to which it is unsuitable; but, if applied to light porous land, unretentive of moisture, the firmness of texture thus imparted would become a real advantage. 2. That this stimulative property is common to every substance that merits the name of manure. That, although gypsum may not be possessed of any nutritive quality in itself, yet, if the land be properly dunged, or otherwise supplied with a sufficiency of other putrescent manure, or of nutritive compost, to support the increased powers of vegetation, and which, in common prudence, should never be neglected, the soil will not, if discreetly managed, suffer any diminution of its accustomed fertility, but will be improved by the large addition made, through the greater luxuriance of the green crops, to the size of the dunghill. 3. That its beneficial effects being confined to some peculiar species of crops, is no real disadvantage; for, when applied to those of a different kind, it has not, in any known instance, been found prejudicial. Its powers appear, indeed, to apply more to the specific crop on which it is spread, than to the state of the soil; and when it has been laid in various quantities-from two bushels to two-and-thirtyon crops to which it is inappropriate, it has been found in all cases wholly ineffectual ‡. It has been assigned by Sir Humphry Davy, in the theory by which the operation of gypsum is governed, as a general standard for its application, that his knowledge and experience of it justify him in the opinion that it is a good top-dressing for grass, and adapted to the growth of turnips, though the quantity spread by himself never exceeded 2 bushels an acre.-p. 347. * Survey of Derbyshire, vol. ii. p. 448. Survey of Huntingdonshire, p. 210. Mr. Parkinson states that he has applied it in all those proportions-namely, 32, 16, 8, 4, and 2 bushels an acre upon the same land, a portion of which was left without that it is the most beneficial to those plants which always afford it on analysis: thus, the ashes of lucerne, sainfoin, rye-grass, and clover, contain considerable proportions of gypsum; but only a very minute quantity is to be found in crops of corn, pulse, or turnips. It is, therefore, essential to the vegetation of the former; and land which has grown tired of clover, may be restored by being dressed with it*, or with peat ashes †, some species of which hold a large portion of gypsum. But when the soil already contains a sufficient quantity of this substance for the support of the cultivated grasses, he considers that its application to them, or even to natural pasture, cannot be advantageous; for plants only require a certain portion of manure, and an excess may be detrimental ‡. The reason why its application to soils is not always efficacious is, probably, because it is furnished by the common course of culture to most well cultivated land in sufficient quantities for the use of the grasses, and perhaps to an excess beyond what other crops require for their growth; for although this may not be apparent to the farmer, it is contained in stable dung, and in the dung of all cattle fed on pasture. A certain portion of it may also be discovered, upon ana lysis, in the natural composition of most soils §. It has been said, by Kirwan, to accelerate putrefaction in a higher degree than any other known substance; but this has been shown by some experiments of Sir Humphry Davy to be incorrect, and it, therefore, cannot be supposed to afford any direct nourishment to plants, either by the corruption of animal remains, or the decomposition of manure. It has been very generally supposed that, as sulphuric acid has a great attraction for water, gypsum acts by its power of attracting moisture from the atmosphere; thus cooling the air in summer, and being more efficacious to dry, sandy soils, than wet clays. It has even been confidently stated, that the dew has been known to stand two hours later in the morning upon plants which had gypsum spread upon them than upon others on which there was none. This, however, has been also contradicted by Sir Humphry Davy, who considers the argument in its favour to be comparatively insignificant; for, when combined with water, it retains gypsum, the whole field equally manured with compost dung, and afterwards carefully sown with rye; but when the crop was reaped, there was not the slightest difference perceivable. The experiment was repeated in a following year upon barley and oats, and the result of each was precisely similar; and as to white crops of any description, it seemed, from his own experiments, to have no effect at all upon them.' -See his Practical Observations on Gypsum, pp. 81, 85, and 95. * Upon an analysis of two fields of different land, one growing good crops of red clover, the other growing them partially or wholly ejecting the plant, the results have invariably shown that those soils which grew the best crops of red clover were those that contained the most gypsum.-Russell on Pract. and Chem. Agric., p. 119. See the following chapter. Elements of Agricultural Chemistry, p. 17. Sir H. Davy analyzed four different kinds of soil; one, a light soil from Norfolk, another, a clay, bearing good wheat, from Middlesex, the third, a sand from Salop, the fourth, a clay from Essex. He found gypsum in all of them; and in the Middlesex soil it amounted to nearly 1 per cent. Lord Dundas also informed him, that having tried gypsum, without any benefit, on two of his estates in Yorkshire, he was induced to have the soil examined for gypsum, and it was found in both soils.-Elem. of Agric. Chem., 4to., p. 291. He mixed some minced veal with part of its weight of gypsum; and also exposed some veal without gypsum under similar circumstances. No difference appeared in the time when they began to putrefy; and the completion of the process seemed to be most rapid in the case in which there was no gypsum. Other similar mixtures were also employed, in some cases with larger, and in others with smaller, quantities of gypsum, and pigeons' dung was, in one instance, used with flesh; but the results were, in every instance, precisely similar.-Ibid., p. 298. Parkinson on Gypsum, p. 78. Blakie on Mildew, 2nd edit., p. 35. that fluid too powerfully to yield it to the roots of plants, and its adhesive attraction for moisture is inconsiderable*: yet, though thus opposed by scientific reasoning, the experience of farmers inclines to the support of the opinion already stated. It is even thought by many people that, when sprinkled over the leaves of plants in a damp state, the paste which it thus forms upon them must prove destructive to the propagation of many insects, and would probably prevent the fly in turnips; but that supposition has not been confirmed by experience. It has been likewise asserted, that its fertilizing powers are destroyed by the effects of sea air, and much of its failure in many parts of England has been attempted to be accounted for upon that principle; but this is in direct opposition to the trials already mentioned to have been made in Kent, and it has been found to answer in Norfolk when applied to land within two miles of the Northern Ocean t. The American farmers lay it upon land newly reclaimed from the forest : it may, however, be doubted whether gypsum contains any inherent property by which it can improve the soil, unless through the means of its fertilizing powers upon the peculiar crops to which it is appropriate, and there is reason to believe that, even upon these, its effects will be comparatively trifling if ploughed in. There cannot, however, be any question respecting its expediency when applied as a top-dressing to artificial grasses at that period of the spring when the plants throw out their first leaves, if spread in portions of not less than four bushels of the finest powder, so equally sprinkled that every leaf should get some, and in weather that is perfectly serene and close. We have afforded the subject more attentive consideration than some persons may suppose it to merit, for it cannot be denied that, in consequence of the disappointment which it has occasioned to many who have tried it without being aware of its peculiar nature, the use of gypsum throughout England has been very generally discontinued; but on a careful review of the very contradictory opinions entertained regarding its effects, we are persuaded that no dispassionate and intelligent farmer can entertain any doubt of its being rendered a source of very important benefit, when used with due discrimination of its powers, and judgment in the mode of its application. We therefore strenuously recommend it to experiments upon a moderate scale; for even should it not be found in the immediate neighbourhood, the cost and carriage are so trifling that a sufficient trial can be made for a few shillings; and we should say that no man who grows a single acre of clover should fail to satisfy himself regarding its real properties. If successful, it may become the means of material improvement upon light loams, and poor chalky soils, which require amelioration through the manure afforded by green crops, as well as to land which, though in better heart, may have lost the power of repeating the production of clover so often as it might be found profitable. No one can justly assert that it is not worth the trial; and, even if unattended with good effect, it can do no harm. To determine this fact with precision, an ounce and a half of gypsum in fine powder was exposed to the air during three foggy nights, and afterwards carefully weighed, when it was found to have given not quite half a grain in addition.-Comm. to the Board of Agric., vol. ii. p. 376, note. + Blaikie on Mildew, 2nd edit., p. 36. CHAPTER XV. MINERAL MANURES, continued.-ASHES-SOOT-SOAPERS' WASTE. ASHES Of every description, including soapers' waste, though not all falling strictly under the character of fossil substances, and, indeed, being partly derived from the vegetable kingdom, yet, partaking in a great degree of the same calcareous nature as those of which we have already treated, may also be allowed to rank together under the general denomination of mineral manures. Those of coal, wood, and turf, when used for domestic purposes, are, in almost all country places, mixed up by the consumers with the dunghill, and, unless they form an unusual proportion of the heap, occasion but little sensible difference in the properties of the manure; but, when applied alone, as top-dressings upon grass, they both strengthen the herbage, improve its quality, and encourage the growth of white clover; they are also generally used for many other crops, both of corn and artificial grasses, but chiefly upon clays and heavy tenacious loams. The ashes of coals, and cinders, have, indeed, the very perceptible effect of loosening as well as stimulating those soils, and when they can be procured in sufficiently large quantities, in the neighbourhood of great towns and manufactories, they are also ploughed in with great advantage, to the extent of 50 or 60 bushels, or even more of the latter, per acre. Those of wood, which forms the chief firing in the interior of this country, are also largely employed by many farmers, who contract with the cottagers for all the ashes they make; drawing home for them in return their faggots. The manure thus procured, being a powerful alkali, has a very considerable effect in correcting any acidity that may exist in the soil, but is, in almost every instance, employed without any distinction respecting the sort of timber from which it is obtained, though, as the trees contain very different qualities, they necessarily yield ashes corresponding, to a certain extent at least, with their original character; and were they classed, and farmers made acquainted with their relative properties, they would be much better able to judge of the due proportion of ashes which it might be expedient to apply to the ground *. It is a well-ascertained fact, that the closer the texture of the wood, and the harder and heavier it is, the greater portion of vegetable alkali it will be found to contain. Thus, by a brief analysis extracted from the Essays of the Bishop of Llandaff, trees may be classed, according to the value of their ashes, as follows: ESF Beech Blackthorn THIRD CLASS. Birch It therefore necessarily follows, that where the kind of timber which has been consumed can be ascertained, the proportion of ashes to be applied per acre ought to vary accordingly; for, if six loads of the best and purest ashes from oak be sufficient, ten or twelve may not be more than equivalent to them when produced from hazel, alder, or sallow; and by the same rule, if ten or twelve loads of oak-ashes were to be sown, A similar remark will apply to the ashes procured from furze; for these are found to possess different degrees of strength, in proportion as they are burned, either in the brick-kiln, the lime-kiln, or the oven. Thus it is well known to most farmers that, in preparing chalk or limestone for burning, in most country kilns, these faggots are very generally used, and being placed in the centre of the pile, as the heat increases, and the stones get into a state of calcination, the action of the fire soon affects all the smaller and looser parts of the stone, which fall down to the bottom, and mix with the ashes. Inasmuch, therefore, as burnt lime possesses a greater stimulus than burnt clay, we may conclude that in the same proportion this refuse from the lime-kiln will be more valuable than that from the brick-kiln; while the ashes produced by the baker's oven must be far superior to either, and may rank in much the same class as those obtained by the burning of -weeds *. The ashes of burnt straw have also been found beneficial by many intelligent practical farmers, from some of whose experiments we select the following instances. Advantage was taken of a fine day to fire the stubble of an out-field soon after harvest, the precaution having been previously taken of sweeping round the boundary to prevent injury to the hedges. The operation was easily performed, by simply applying a light to windward, and it completely destroyed every weed that grew, leaving the surface completely covered with ashes; and the following crop, which was wheat, produced full five quarters per acre. This excited further experiment, the result of which was, that in a following season, the stubble having been partly ploughed in according to the common practice, and partly burned, and the land sown with wheat, the crop produced eight bushels per acre more on that portion which had been burned, than on that which had been ploughed-in. The same experiment was repeated, on different occasions, with similar results; and a following crop of oats having been laid down with seeds, the clover was found perfectly healthy, while that portion on which the burning of the stubble had been omitted, was choked with weeds t. To which we must add, the experiment on the efficacy of burnt straw, as stated in p. 248 of this work, which, though not supporting the superiority of corn crops over those manured with dung, yet, on those two, in which alone it could have been supposed to have taken effect, it bore a very near degree of equality. It must, however, be recollected, that if intended to have a decided effect, the stubble must be left of a considerable length, which will occasion a material deficiency of farm-yard manure; though the advantages will be gained of saving the cost of moving the stubbs, the seeds of weeds and insects will be considerably destroyed, and the land will be left unimpeded for the operation of the plough. On the wolds of Lincolnshire, the practice of not only burning the stubble, but even the straw of thrashed grain, has been carried, in many cases, to the extent of four to six loads per acre; and, as it is described in the Report of the County, has been attended, in all those instances, with very decidedly good effect. It is even said to have been found superior, in some comparative trials, to yard-dung, in the respective rate of five tons because it may have been the custom to use that quantity of hazel, &c. the effect might be found, in a dry season, to burn up the crop. See Malcolm's Comp. Modern Husb. vol. ii. p. 178. * Malcolm's Comp. of Mod. Husb., vol. ii. p. 184. Survey of the East Riding of Yorkshire; Communications to the Board of Agric., vol. iv. p. 130. |