Essays in Natural History and Agriculture Part 5

41 1/4 bushels in patch No. 1, 36 " " No. 2, 41 1/4 " " No. 3,

and in that part of No. 3 which was also covered with guano, it reached by actual weight (not by estimate), 53 bushels of 60 lbs.

to the acre. Those patches in Nos. 1 and 2 which had guano put on them, suffered so much from the depredations of the birds, that no account was taken of them separately. The crop was cleared off the land, which was cleaned, and again sowed with wheat on 3rd October, 1843. It was drilled in rows seven inches apart, and at the rate of 2 1/2 bushels to the acre. It is to the results of this crop that I now wish to call your attention. Before sowing, the land was subsoiled to the depth of from 14 to 16 inches; except a strip of about 10 feet in width, down the middle of the field, which was left untouched for the purpose of determining what were the advantages derived from subsoiling. If the advantage was merely that of thorough draining (for the field had not been thoroughly drained previous to the subsoiling), it was thought probable that this strip of 10 feet wide would be drained by the subsoiling on each side of it; but if, in addition to this, the wheat plant derived more nourishment by striking its root deeper into the soil, where that was loosened by the subsoil plough, the crop ought to be better in the subsoiled than in the unsubsoiled part. The field runs over the ridge of a hill, and upon that ridge the soil is so poor and thin, that it was deemed expedient to give it a slight dressing of coal-ashes and night-soil, from an idea that the plant would scarcely survive the winter unless some stimulus were applied there; but the ashes contained little manure, and were only applied to the worst part of the field, covering about one-third of its surface. The wheat was Spalding's Prolific; it came up evenly and well all over the field. It was hand-sowed with lime early in February to the extent of about 24 cwt. of dry lime on the acre. In order to ascertain the value of lime, and the proper quant.i.ty, I had the field uniformly covered with it, except one land, which was left entirely without, and the headlands, which had one three, the other six times as much lime put upon them as any other part. The field was also dressed with a chemical manure of the following ingredients on the 16th March, costing:--

L. s. d.

1 1/4 cwt. nitrate of soda 0 17 6 1 " impure sulphate of magnesia 0 5 0 3/4 " silicate of soda 0 11 3 3/4 " common salt 0 2 0 1 1/4 " gypsum 0 2 0 Mixing and applying it, say 0 2 3

Total for statute acre L2 0 0

Speculating on the probability of a dry summer, I gave it an extra quant.i.ty of manure, and I think where guano is used afterwards, as it is by me, the nitrate of soda might be dispensed with, which would bring the cost to L1 2s. 6d. per acre. I should prefer guano to nitrate of soda, because of the phosphates contained in the former. At the distance we are from the sea (about thirty miles) it would seldom be necessary to apply common salt, as the gales of winter generally bring as much as is needed; but last winter we had no high winds, and I thought that where salt was applied with other chemical manures, the wheat was more luxuriant than where there was none; but owing to a misunderstanding of the instructions to that effect, the produce was not kept separate. When the chemical manure was applied, one land was left without, for the purpose of comparison. Guano was sowed on the land on the 29th March, at the rate of something less than 2 cwt. to the statute acre, one side of the field being covered with Peruvian, the other with African, and the land on which no chemical manure had been sowed was half of it covered with guano, and the other half left without anything except lime; but as it was thought desirable to ascertain the value of the chemical manure without guano, half of this patch was sowed with the chemical manure in April, after the long drought of the last spring had set in. A small patch was left without manure, to show the natural condition of the field, and to serve as a comparison with the manured part alongside it, and also with the condition of the field when the experiment commenced, 1841-2, when the unmanured portion yielded only 19 2/3 bushels to the acre. This part of the experiment, however, was frustrated by the carelessness of the men who thrashed out the wheat. The crop was a very good one throughout the field, but was evidently shorter and thinner where there was no lime, and also where guano was applied alone. It was best on the headlands where more lime had been applied. The weather was extremely favourable until the wheat was going out of bloom, but it then changed, and the crop was beaten down by the rain, in some places so thoroughly that it never rose again; and from that time to the day it was reaped (21st August), there were not more than six fine warm days. This cold and ungenial weather would, no doubt, materially affect both the quant.i.ty and quality of the crop,--the sample only being just fair. On thrashing out the crop, I find the result to be as follows:--Where the guano and chemical manure were applied, but no lime, the yield was 49 1/5 bushels of 60 lbs. per statute acre; where the land was left unsubsoiled, it was 52 1/2 bushels; when guano alone was applied, it was 42 1/3 bushels; where the chemical manure alone was applied, it was 43 1/2 bushels; where the African guano was applied, it was 45 bushels; where the Peruvian was applied, it was 52 2/3 bushels; on the headlands, where three times the quant.i.ty of lime (or 3 1/2 tons per acre) was applied, it was nearly 62 bushels; and where six times the quant.i.ty of lime (or 7 tons to the acre), it was 49 2/3 bushels. I give this last result as it was ascertained, but do not consider it conclusive, for the wheat plant on this headland looked quite as well as the other, until it went out of bloom, when from some unknown cause it was partially blighted; an irregular patch from a foot to a yard in width and extending almost from end to end of the headland becoming brown and parched, as if affected by lightning or some atmospheric visitation. With the view of making these results a little clearer to the eye, I subjoin the following tabular statement of the produce per acre in the different parts of the field:--

Bushels of 60 lbs. per statute acre.

Guano alone 42 1/3 Chemical manure alone 43 1/2 Guano and chemical manure, with 24 cwt.

lime to the acre, but land unsubsoiled 52 2/3 Guano and chemical manure, but no lime 49 1/5 African guano and lime 45 Peruvian " " 52 2/3 " " and 3 times as much lime 62 " " and 6 " " 49 2/3 Average crop throughout the field 50

It may be as well to observe, that the total expense of manure, and of its application to that portion of the field which produced sixty-two bushels per acre (including the guano and the additional quant.i.ty of lime used), was at the rate of 81s. per statute acre.

Deducting the cost of the nitrate of soda, the utility of which, under the circ.u.mstances, I am inclined to doubt, it would have been 63s. 6d. I consider these to be very favourable results, and as offering strong inducements to continue the experiment. I have accordingly had the land ploughed up and cleaned; and it was again sowed with wheat on the 9th inst. Having detailed the general results of the experiment, I beg to offer the following remarks upon some points in it, which seem to me to require a little elucidation. I consider the success of this experiment to be in a great measure owing to the use of soluble silica and magnesia; because, although there is an abundance of silica in the soil, my first crop showed very miserable results, the grain being ill-fed and poor, and the straw soft and discoloured, although the year 1842 was, in this district, very favourable for wheat, the month of August being singularly fine and warm; but when I combined the nitrate of soda with sulphate of magnesia, as in experiment No. 1 in 1843, but still more so when I combined it with the silicate of soda, as in No. 3 of that year, the straw became as strong, firm, and bright as need be desired; and this year when both these salts are combined with nitrate of soda, common salt, and gypsum, I have not only good and bright straw, but also an abundant crop of wheat.

With respect to the lime used, it may be as well to state that the field had not been limed for many years, and although in a limestone district, showed a deficiency of lime on a.n.a.lysis. The soil is a strong loam, on a brick clay subsoil, in which there is little or no lime, although the stony clays, which form the subsoil in a great part of the district, abound in it, containing from twenty to thirty per cent. of carbonate of lime. I had always believed that lime was used in great excess in this neighbourhood, and had, in fact, an idea that its good qualities were overrated, inasmuch as it does not enter into the composition of the plant, except in very minute proportion; but last winter I saw a paper (by Mr. Briggs of Overton) on the possibility of growing wheat on the same land year after year, in which the utility of lime in preventing rust was incidentally touched upon. I also saw Liebig's letters explaining the action of quicklime in liberating potash from the clay; and then I considered it very important to ascertain the proper quant.i.ty to be applied. The quant.i.ty required to decompose the phosphate of iron was not great, and a.s.suming Liebig's theory of its action in liberating the potash to be true, it seemed to me that an excess of lime would permanently impoverish the land; for, supposing that the crop required 100 lbs. of potash, and as much lime was applied as liberated 500 lbs., what became of the 400 lbs. which did not enter into the composition of the plant? was not a large portion of this 400 lbs.

washed down the drains by the rain, and so lost for ever? Perhaps the absence of lime in this field accounts for its beneficial action in the experiment just detailed; but if my supposition is correct, that any excess of potash which may be liberated from the clay by the use of quicklime (that is, any more than may be required to perfect the crop), is washed down the drains, and thus the land is permanently impoverished by the excessive use of lime, it behoves landed proprietors to ascertain what is required, and they should take care to apply no more than is necessary. This caution is most particularly needed in this neighbourhood, where lime is cheap, and where the opinion is prevalent that the more there is applied the better it is for the land, and where it is common to apply ten or twelve tons to the acre. I have stated above that chemical manure was applied to a small portion of the field after the setting-in of the drought in April. The action of this manure showed that a good thing may be very injurious if applied at an improper time; for, although it produced a stimulating effect on the plant immediately after its application, there was too little moisture in the land to dissolve it thoroughly, and thus enable the plants to appropriate it, until the rain came, about the end of June, when the wheat had been in flower some time; but the stimulus was then so great that all the plants threw up fresh stalks (from the roots), which were in flower when the wheat was cut, and it was then found that they had not only impoverished the plants, but had prevented the grain from ripening. This was the case not only in the experimental field, but in several others also, where the chemical manure was sowed after the setting-in of the drought. When the field was sowed with guano, it was thought desirable to cover one part of it with the African, and the other with Peruvian, for the sake of comparison; but as the African did not appear to produce the same stimulating effect as the other, fifty per cent. more was applied, that the cost might be equal (the Peruvian cost 10s., the African 7s. per cwt.); but as the latter application of the African was made when the wheat was just shooting into ear, the same objection applies to the experiment which does to the chemical manure applied after the drought had set in--viz., that there was not sufficient moisture in the soil to dissolve it thoroughly until the plant was too far advanced to benefit by it; and therefore its failure would be no proof of the value of the African as compared with the Peruvian, which was the object of the experiment. It is true, no bad effects followed the application similar to those produced by the misapplication of the chemical manure in dry weather, yet if soluble salts like the latter did not find sufficient moisture in the ground when applied in April, there is reason to suppose that the former would not do so when applied in May. I regret the failure of the experiment without any manure, as I think the result would have shown satisfactorily that the land is so far from being impoverished by this system of cropping, that it is improving every year. I think, however, that this is shown by the produce of the land manured with guano alone. In the first year's experiment the produce from guano alone was 27 bushels per acre, and both straw and wheat were very indifferent in quality. This year the produce from guano alone is 42 1/3 bushels; and although neither straw nor wheat are so good as upon the adjoining lands, they are both very much better than they were in 1842. It will be observed that the result from the unsubsoiled portion is very good, and if nothing more were said about it, people would be led to conclude that there was no advantage in subsoiling. But this, in my opinion, would be a great mistake; for to say nothing of the advantage which the unsubsoiled portion would derive from the drainage which it received from the subsoiling on each side of it, I found, when the field was ploughed up this autumn, that whilst the unsubsoiled portion was stiff and heavy, the subsoiled part was comparatively friable and loose, like a garden, and will, I expect, show its superiority in the succeeding crops. It must be borne in mind, in reading these experiments, that we have here one of the most unfavourable climates in the kingdom for growing wheat, from the excessive quant.i.ty of rain that falls, three times more rain falling annually in the north of Lancashire than at York, and this, no doubt, is very prejudicial to the success of such a series of experiments as I have been detailing. It has been objected to these experiments, that allowing all to have been done which is here detailed, it leads to no important conclusion; for although it may be practicable to grow wheat every year, in a small field like the one experimented on, it is not so on a large scale. But the objectors should remember that there is not the seed of a single weed sowed with the manure; and therefore if the land is thoroughly cleaned, and kept so, by hoeing the crop in the spring, it will require very little labour to fit it for another.

But I shall be better able to speak on this head next harvest, having sowed wheat on an oat stubble with once ploughing. It is said there are no weeds in Chinese husbandry, and if they can eradicate them completely, so may we, if we adopt the same methods and follow them up as perseveringly. Again, admitting that it is not practicable to grow wheat on the same land year after year on a large scale, yet if we can double the crop in those years in which we do grow it, by the application of chemical manures (and the same manures are applicable to all cereal crops), will not that be a conclusion worth arriving at? That it is possible to do so, is, I think, sufficiently shown by the results I have obtained. What, then, may we expect when these experiments are infinitely multiplied and varied, under the superintendence of skilful and experienced men, who will devote their whole time and attention to the subject? Will raising the average produce from twenty-five to fifty bushels per acre be the utmost limit to which improvement can be carried? I believe not. In conclusion, I would urge on all owners and occupiers of land, the importance of devoting at least a small field to agricultural experiments, as I think there can be no doubt that, if these are carefully and systematically made and followed up by agriculturists generally, we shall be so far from needing an importation of corn in average years that we shall have a large surplus to spare for our neighbours.

NOTE.--In the use of silicates of soda and potash one precaution is very necessary--viz., that you really have a soluble silicate, and not a mere mechanical mixture of ground flint and soda: this is a very different thing, and one, if it be not carefully guarded against, which will lead to nothing but disappointment. Again, the silicate may be properly made in the first place, but in a long exposure to the atmosphere the soda attracts carbonic acid, and the soda is liberated, and this has defeated my expectations more than once. Again, though I consider it desirable to defer the application of it until vegetation has fairly started in the spring, yet, in one instance, I delayed the application of it so long, that there was not moisture to dissolve it until the end of June, and then the wheat began to shoot afresh from the roots and the crop was seriously injured by it: but this was in an exceedingly dry spring, and might not happen again for many years.

_To the same._

LOW MOOR, _18th December_, 1845.

SIR,--I promised to communicate to you the results of my attempt to grow wheat on the same land year after year, this being the fourth crop of wheat (the fifth white crop) grown in successive years on the same soil, and though I consider the crop an indifferent one, I don't think the failure ought in any degree to be attributed to the over-cropping, but to the wetness and coldness of the season, as well as other untoward circ.u.mstances hereafter to be mentioned.

In a former letter of mine of the 12th October, 1844--which was published in the "Guardian" a few days after--I gave an account of the crop of 1844, which was a very good one, being fifty bushels to the acre throughout the field, and as much as fifty-two bushels in the best part of it. This I considered so satisfactory that I had the field again ploughed up and sowed with wheat on the 9th October, 1844, and it is to the results of this crop that I wish to call your attention. As remarked in my former letter, the field was subsoil ploughed in the autumn of 1843, and this subsoiling was carried to such a depth that most of the drains in the field were more or less injured by it; and although this did no injury to the crop of 1844, owing to the very dry season, yet when the rain came in the winter of 1844, the want of drainage was found to be very prejudicial, and in the wet places large patches of the young wheat went off altogether, and there was a great deficiency of roots in many parts of the field; the long continuance of frost and after that the ungenial weather which continued so long in the spring (of 1845) were also unfavourable, yet with all these drawbacks the appearance of the plant after the growing weather _did_ come, was very promising, and many of my friends predicted that I should have as good a crop as in 1844. On the 24th March I applied chemical manure of the same kind as I had done in 1844, at the rate of about 3 1/4 cwt. to the acre (costing 23s. 6d.), and a fortnight after I had it sowed with 2 cwt. of guano to the acre.

When the warm weather came, these manurings seemed to help it wonderfully, and it was, as I have before stated, a very promising crop; but the cold, ungenial weather we had through a great part of the summer, and the continued rain we had whilst the wheat was in flower, destroyed all the former promise: and the manuring with guano, so far from being beneficial, was very injurious--so much so, that I believe every shilling's-worth of it applied to my wheat this year, made the crop a shilling worse than if nothing had been applied; and all ammoniacal manures had the same effect.

It may be asked how I know it was the guano, and not the chemical manure. In answer to this inquiry, if made, I may observe, that I supplied two of my neighbours with the chemical manure, and they applied it without guano on very poor land, and they both a.s.sert they had never such good crops of wheat before; but everywhere in this neighbourhood, the only good samples of wheat that I saw or heard of were grown on exhausted soil. This appears to me to be a strong proof that chemistry has a great deal to learn before it can adapt its measures to all varieties of seasons, particularly as it cannot know beforehand how the season may turn out. If further proof be required of the injurious effect upon grain crops of ammoniacal manures in general, and of guano in particular, I may mention that in another field of wheat, sowed on the 21st December, and which did not come up until the frost broke, in March (the previous crop having been Swedes), the blade was so yellow and the plant altogether so small and sickly in appearance, that I had it manured with a water-cart from a cesspool in April.

This appeared to produce a wonderful improvement immediately, as the plant a.s.sumed a deep green and grew very fast, but when it ought to have shot, the heads seemed to stick in the sockets, the blade and straw became mildewed and made no progress in ripening.

It was not fit to cut for three weeks after the experimental field, although it was an early white wheat, and the result was a miserable crop--far worse than the experimental field. The instance of injury from the use of guano, I had from a neighbour, who told me he had sowed a patch of oats with it, and that they never ripened at all, and that he was compelled to cut them green as fodder for his cattle. I had a striking proof this season of the much lower temperature required by oats than wheat, when strongly stimulated by manuring. I had gathered an ear of wheat and a panicle of oats the previous season, which seemed to me to be superior varieties; and that they might have every chance, I dibbled them alongside each other in my garden, and determined to manure them with every kind of manure I could procure, as I had an idea that it was not easy to over-manure grain crops, if all the elements entering into the composition of the plant were applied in due proportion to each other, and I also wished to ascertain whether wheat and oats would thrive equally well with the same sort of manuring. I accordingly limed the land soon after the wheat came up, and in March I applied silicate of soda, sulphate of magnesia, gypsum, common salt, and nitrate of soda. A fortnight after this I applied guano, then bones dissolved in sulphuric acid, then woollen rags dissolved in potash (the two latter in weak solution); and the consequence was, that I don't think there was a single grain in the whole parcel--at least I could not find one--the straw was no great length, and the blade much discolored with mildew, whilst the oats were seven feet high, and with straws through which I could blow a pea, and large panicles, although the oat was not particularly well-fed. The inference I have drawn from these experiments is, that as far as is practicable the manuring should be adapted to the temperature, but as this is obviously impossible in a climate like ours, the only way is to rather under than over manure, and to apply no ammoniacal manure to the wheat crop, or at all events very little; for although guano was beneficial to wheat when used in conjunction with silicates, &c. &c. in 1844, yet the injury it did in 1845 may very fairly be set against that benefit. I should feel obliged if any of your readers who may have tried the experiment of manuring grain crops with guano, the last season (1845) would publish the result as compared with a similar crop without such manuring. I feel convinced that such result would be against the use of guano for wheat in 1845. I am the more confirmed in the opinion that ammoniacal manures are unfavourable for wheat, by a series of articles in the "Gardener's Chronicle" on the "Geo-Agriculture of Middles.e.x," in which the writer states that land in that county which in Queen Elizabeth's time produced such good wheat that it was reserved for her especial use, will now scarcely grow wheat at all, and when that grain is sowed upon it, the straw is always mildewed, and the sample very poor; and this is attributed--and no doubt justly so--to the extensive use of London manure. My crop was only 32 bushels to the acre of 60 lbs. to the bushel; last year the crop, as I have said before, was 50 bushels of the same weight.

_To the same._

c.l.i.tHEROE, _7th March_, 1848.

On continuing my attempts to grow wheat on the same land year after year, I observed that the crop of 1845 was very seriously injured by the deficient drainage--the old drains having been destroyed by the subsoil plough. It was therefore necessary to replace them: they were accordingly put in four feet deep. This occupied so much time that the season for sowing wheat had gone by, and the ground was cropped with potatoes, which were got up in September, and the wheat might have been got in early in October.

But seeing in your paper that sowing too early was not advisable, and also being carried away by the arguments of the thin-seeders, I deferred sowing until the middle of November, and then put in little seed; and the winter proving very unfavourable, when the wheat was coming up, there was not half plant enough in the spring, and I hesitated whether to plough up the ground or drill in barley. I determined to do the latter, which was done on the 18th April, and wheat and barley grew up together, and when cut and threshed, proved to be equal to 48 bushels to the acre.

LOW MOOR, _31st December_, 1844.

HENRY BRIGGS, ESQ.

I duly received your obliging letter in reply to my pamphlet on the growth of wheat year after year on the same land, and now offer my rejoinder to your remarks. You seem to consider the expense is too great under the system pursued by me; and that it was more than was required by the crop, is proved in my opinion by the fact that the fertility of the land is very much augmented since the commencement of the experiment in 1841: as my first crop with guano alone produced only 27 bushels per acre, whilst this year from guano alone the produce was 42 bushels. But still I think that your allowance of manure is far too little, and not exactly what I should apply, and I shall frankly state my objections and opinions, in the hope that they may elicit a reply from you, as it will be from discussion and the experiments inst.i.tuted to test the various theories propounded, that agriculture will be most materially benefited. You state that Liebig's present theory is, that plants obtain the necessary oxygen, hydrogen, carbon, and nitrogen from the rain and atmosphere, and that the plants merely require the supply of inorganic const.i.tuents, and that you are inclined to agree with him. My copy of his work on the Chemistry of Agriculture is his first edition; and I don't know how far he has since modified or altered the opinions therein expressed, which are in some degree at variance with each other. He states that it may be received as an axiom in agricultural chemistry that the nitrogen of the atmosphere is never a.s.similated by plants, except in the form of ammonia or nitric acid. He certainly states that plants and animals derive their nitrogen from the atmosphere; but why, if this be true, does he attach so much importance to the excrements (particularly urine), of men and animals being husbanded with so much care? and he states that for every pound of urine wasted, a pound of wheat is thrown away. But even if he said it was utterly worthless, every practical farmer who has tried it knows how exceedingly valuable it is. It may be said there are other ingredients in urine besides ammonia, and these are what make it valuable; and in reply to this I would ask what is it that makes the ammoniacal liquor from gasworks so valuable? There are no phosphates or alkalies there, and yet what a powerful stimulant it is. Again, Liebig states that the carbon is derived from the atmosphere; but to say nothing of the argument which might be deduced from the advantage which is derived by plants from having their soil loosened about their roots, the experiments of Dumas and Boussingault prove that a tree which was cut off below the branches expired a large quant.i.ty of carbonic acid. It may be asked how I know this was not precipitated by the rain. I don't know; but if the plant would a.s.similate this, why should it not a.s.similate that which arises from the decomposition of the carbonaceous matter in the soil? My idea is that it does both, and that carbon in the soil does good if it offers an abundant supply of carbonic acid to the plant when it is in a condition to appropriate it. Your allowance of lime appears to me to be far too small, for if any reliance can be placed on my experiments, lime can be profitably used to far greater extent than you seem to imagine. And, again, you seem to think that where there is plenty of silex in the soil, the plant will be able to obtain as much as it requires. I think that it is quite necessary that the silex should be in a soluble state, as I think that it is not only desirable that all the elements necessary to fertility should be in the soil, but that they should be in such a form that they can be a.s.similated by the plant. Some of our compounds for producing fertility may perhaps be as absurd as it would be to give muriatic acid to a man troubled with indigestion, because free muriatic acid is found in the stomach of a healthy person.

Let me recommend you to try both silex and magnesia in a soluble state, and I think you will be satisfied with the benefit derived from their use.

Recurring again to the quant.i.ty of manure necessary to grow thirty-six bushels of wheat, I would ask, why limit yourself to so small a crop? The difference in the cost of your manuring a field, and my manuring it, is more than made up by the increase of fourteen bushels of wheat and the corresponding increase of straw, even if the land did not improve every year by the application; and as the seed, rent, labour, and liabilities of the land are the same whether you grow a small crop or a large one, why not have it as large as possible? Again, if I applied far more manure than was necessary, I ought to have had the crop equally good throughout the field; but on the ridge of the hill, where the soil was thin and poor, neither straw nor wheat were so good as they were where it was deeper and richer. My own opinion is, that the plant is never able to extract from the soil all the manure, and therefore it ought to be brought up to a good standard before good crops can be expected. I am not satisfied with any a.n.a.logy that I can think of, but the best that occurs to me is that of a cloth in a dye- copper. You can never get it to absorb either all or half the colouring matter, and if you don't use far more than is taken up by the cloth, you will never obtain the desired results. Besides, in chemical combinations it is desirable to use far more than the chemical equivalents, or the experiments don't succeed. I perceive that you intend to use guano next year, and that you intend to use it along with the seed. I trust it will not be sowed in contact with either the seed or the quicklime, which you proposed to use in some of your land. The best time I have found for applying guano is in wet weather, just when vegetation is making a start in the spring--say the last week in March, or the first week in April--as I fear a large part of the soluble portion of it would be washed away by the rains of winter. It is true we have had none this winter, but when shall we have such another? Did you ever use woollen rags as manure? They ought to be excellent, as they are almost all alb.u.men, and are, I fancy, to be had at a very moderate price, not far from you. Can you inform me what it is that causes the land to be clover-sick? If it is the abstraction of something from the soil, what is that something? Sir Humphrey Davy said that a dressing of gypsum would prevent it; but clover does not succeed here (even when dressed with gypsum), if sowed every four years.

One reason why I think so small a quant.i.ty of manure will not succeed, is based on the theory of excrement.i.tious secretion.

Decandolle proved that this secretion took place, but he did not succeed in proving that it poisoned the land for a similar crop. I can only reason from a.n.a.logy, and it does not follow that an a.n.a.logy drawn from animal life will hold good when applied to plants; but if we were to feed an animal with pure gluten and pure starch, with the proper quant.i.ty of phosphates, &c., are we to suppose it would have no excrements? Let this be applied to plants: are we to suppose that the plant a.s.similates all that is absorbed by its roots and leaves? When that which is absorbed is what would enter into the composition of the plant, is it not more rational to suppose that the inorganic and gaseous const.i.tuents only combine in fixed proportions, and that although the plant may absorb a much larger proportion of one than is required, the surplus is discharged excrement.i.tiously, and perhaps may be unfitted for entering into the plant until it has undergone a decomposition? In conclusion, I trust you will pardon my frankness in so boldly canva.s.sing your opinions; but it is in this collision of opinion that the truth will be elicited, and if I judge you aright, it is that you wish to discover whether it harmonizes with your preconceived notions or not.

LOW MOOR, _1st May_, 1845.

HENRY BRIGGS, ESQ.

I duly received your pamphlet on the use of lime, for which I am much obliged, and am delighted to perceive that you confirm the idea (expressed in my pamphlet on the growth of wheat every year on the same land) that the excessive use of lime is ultimately injurious to the fertility of the soil to which it is applied.

This, coming from a gentleman of your reputation and experience, will, I hope, induce someone capable of performing the experiment to endeavour to ascertain with precision how much lime it is desirable to apply to an acre to give the best results, and with the least waste, a.s.suming that the land contained little or none previous to the experiment; and it would also be desirable to ascertain whether it is better, in an economical point of view, to apply a small quant.i.ty every year, or a larger quant.i.ty every third or fourth. My own opinion is in favour of the former method, except that it is difficult to get it ploughed in, particularly in wet weather, immediately after spreading (which is essential where you grow wheat on the same land every year) without injuring the feet of the horses. You speak of ten days or a fortnight being necessary to neutralize caustic lime, but our horses had their feet injured by it six weeks after it had been spread on the land, last year, although the weather had been wet almost the whole of the time, say from the beginning of February to the middle of March. You appear to think that lime will replace silica in the wheat plant. Whose authority have you for this? It will be very important to establish this supposition, but I fear it is too good news to be true. On referring to your letter, I find you don't say what I supposed you did, but that the lime liberates the soluble silicates, potash, &c. This may be, and certainly the beneficial effects of lime in growing wheat are not to be explained by any other hypothesis with which I am acquainted. I am this year trying some experiments to ascertain (if I can) the cause of clover- sickness, and I hope to be in a position to say whether your supposition that lime, gypsum, &c. will prevent it, is correct. My experiments so far are opposed to this theory, but it is not very safe or philosophical to draw conclusions from one or two experiments only. I doubt the possibility of making silicate of soda by merely mixing lime, sand, and salt together, as my chemical friends tell me this cannot be accomplished unless the silex and the alkali are fused together. If a soluble silicate of soda can be made in the way you mention, it will be a great saving of expense. Has it been tried? You have no doubt seen a report of the enormous crop of wheat grown in a field in Norfolk last year (90 bushels to the acre), and that the Royal Agricultural Society have determined to have the soil a.n.a.lyzed by Dr. Playfair. This is very desirable, but as Dr. Playfair is more of a lecturing than an a.n.a.lyzing chemist, I think it is very necessary that his a.n.a.lysis should be checked by another, made by the most eminent chemist that Europe can produce, for 90 bushels is so unheard-of a crop, that no expense should be spared which would enable us to ascertain what the soil contained to enable it to produce such a crop, which is the more remarkable as the field seems to have been a good many years under the plough. As your Wakefield Farmers'

Club has many wealthy members in it, allow me to hint the desirableness of your undertaking this a.n.a.lysis, which, if properly performed, will be worth a thousand times more than its cost. When you are aware that even Davy missed 16 per cent. of alumina in one of his a.n.a.lyses and that the chemists of the present day don't seem to have detected the potash which exists so abundantly in potato-tops, you will, I think, agree how exceedingly important it is that such a.n.a.lysis should be checked by others, made without any communication between the parties. You speak of an original letter of Liebig's appearing in the "Farmer's Journal." On what subject is it? as I have no means of referring to the periodical in question. Does it throw any light upon the new manure for which he is said to be taking out a patent? You speak of humus and humic acid. What do you understand by humus?

as, according to Liebig, humus sometimes means one thing and sometimes another, and he appears to treat it very much as modern chemists treat phlogiston, as something which they don't comprehend, but which they need to explain the phenomena of vegetation. If you are a believer in humus, what is it composed of, and how does it act in forwarding vegetation? I suppose you will reply, By combining with oxygen and forming humic acid. But would not the theory of the decomposition of carbon do quite as well? I don't perceive the injurious effects of quicklime upon gra.s.s land which you antic.i.p.ate in your paper, but the contrary, and the more caustic it is the more beneficial is its action, so far as I can judge from my own experiments; and it is my practice in liming gra.s.s land to spread it as soon as I can get it into the state of flour. I shall be glad to hear the result of your electrical experiment--at present I am rather sceptical on the subject.

P.S.--Am I to suppose that you have abandoned the idea of manuring an acre of wheat for thirteen shillings?

THE CULTIVATION OF WHEAT.

_October 1st_, 1852.

To the Editor of the "Manchester Guardian."

The increasing quant.i.ty of agricultural produce consumed in this country makes it desirable that the cultivation of the land should be carried to the highest point consistent with profit; and the increasing scarcity of agricultural labourers will shortly render it difficult for the farmers in some districts to gather in their crops. It therefore becomes increasingly desirable that every mechanical contrivance which will facilitate their doing so should be made as perfect as possible; and also that the crops themselves should be so cultivated as to make these mechanical aids to work to the greatest advantage.

But it has been a difficult matter (at least in the wet climate of Lancashire) to ascertain how far it is prudent to manure for wheat, for in unfavourable seasons the plant runs so much to straw that it is liable to lodge, and become mildewed; in which cases the manure is not only wasted, but becomes positively injurious, as appears to be the case in the South of England this year, and as was also the case in the North in 1845, when every shilling expended in manuring the wheat crops of that year made the crop at least a shilling worse than if no manure had been applied.

But if we could find a wheat so short in the straw that it would bear heavy manuring without being lodged, wheat-growing would be a far less hazardous occupation than it is at present, and we might confidently calculate on a far greater production than we can now.

The following appear to me to be some of the advantages of growing a short-strawed wheat:--

1st. It will bear highly manuring without lodging, and with much less liability to mildew, than a long-strawed wheat.

2nd. The proportion of grain to straw is greater in short than in long-strawed wheat.

3rd. As it very rarely lodges, it will be far better suited to the reaping-machine than a long-strawed wheat; and no doubt other advantages will occur to the minds of experienced agriculturists.

When making these a.s.sertions I ought to state that my experience of wheat-growing does not extend beyond the counties of York and Lancaster, but from what I can learn of the agriculture of more southerly districts, I fancy these opinions of mine will be found correct even there. I may be asked to prove my a.s.sertion, and I will endeavour to do so.