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Manures and the principles of manuring
by Charles Morton Aikman
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Highland Society's Experiments.

Valuable experiments have been carried out on the subject of manuring of turnips by Dr A. P. Aitken, for the Highland and Agricultural Society of Scotland. The following are some of the results to be gathered from these experiments. The effect of a dissolved phosphate as compared with a ground phosphate is to produce a turnip of less feeding value. Superphosphate had a better effect when applied in April than when applied with the seed in June. It was further found that when the nitrogenous manure was given entirely in the form of nitrate of soda or sulphate of ammonia, the latter produced a denser and sounder turnip. Lastly, with regard to the application of potash, it was found that the best way was to apply it several months before sowing. The effect of potash manures is to increase the amount of turnips, but to retard the ripening of the bulbs. The effect of excessive potash manuring is to greatly injure the crop.

Manuring for rich Crops of Turnips.

In Dr Aitken's own words: "In order to grow a large and at the same time a healthy and nutritious crop of turnips, such a system of manuring or treatment of the soil, by feeding or otherwise, should be practised as will result in the general enriching and raising of the condition of the land, so that the crop may grow naturally and gradually to maturity. For that purpose a larger application of slowly acting manures, of which bone-meal may be taken as the type, is much better suited than smaller applications of the more quickly acting kind. A certain amount of quickly acting manure is very beneficial to the crop, especially in its youth; but the great bulk of the nourishment which the crop requires should be of the slowly rotting or dissolving kind, as uniformly distributed through the soil as possible."

Experiments by the Author.

Experiments by the author on turnip-manuring, carried out in different parts of the South and West of Scotland, showed that while farmyard manure is valuable in giving the crop a good start and bringing it well forward during the period of germination and early growth, by supplying a certain amount of easily assimilable plant-food, and in the case of dry weather attracting a quantity of moisture, its application in quantities of 20 or even 10 tons per acre can scarcely be regarded as profitable, giving to farmyard manure a nominal value of a few shillings a ton. In these experiments slag proved itself a most valuable manure, indeed one of the most economical of all the manures experimented with. They further showed that heavy dressings with superphosphate, amounting to as much as 8 cwt. per acre, are, from an economical point of view, as a rule justifiable in Scotland; and that nitrate of soda and sulphate of ammonia possess practically equal value as a manure for turnips. In almost every one of the experiments the benefit of supplementing superphosphate with nitrogenous manure was shown. Potash was also found in many cases to be a thoroughly paying manure for the turnip crop, when it was applied along with nitrogen and phosphates; but when applied alone, far from exercising any appreciable benefit, it seemed to exert an injurious action.

POTATOES.

Potatoes are often classed along with the root crops, and in their manurial requirements they offer many points of similarity. Next to root crops, they may be said to make the most exhaustive demands on the soil, and therefore require a liberal general manuring. A point of importance in the manuring of potatoes is a good tilth in the soil, so as to enable a free expansion of the tubers to take place. They may be said to grow best on deep warm soils; but, like roots, if liberally manured, they may be successfully grown on any kind of soil. Farmyard manure has long been regarded as specially valuable for the potato crop. In many parts of Scotland it is applied in enormous quantities, ranging from 20 to even 40 tons per acre. There can be little doubt that the value of farmyard manure, as well as other bulky manures, for the potato crop, is partly due to their mechanical influence on the soil. Potatoes are surface-feeders, and require their food in a readily available condition. It is found desirable, therefore, to supplement farmyard manure by readily available artificial manures. Potatoes repay the application of a mixed manure containing all the fertilising ingredients—nitrogen, phosphoric acid, and potash—better than most crops.

Highland Society's Experiments on Potatoes.

The nitrogen is, according to the Highland Society's experiments, best applied in the form of nitrate of soda. Sulphate of ammonia does not seem, when farmyard manure is also applied, to have an equally valuable effect, as it influences the size of the tuber, producing an undue proportion of small potatoes. When no farmyard manure is applied, however, sulphate of ammonia seems to have a good effect, especially in wet seasons.

With regard to the nature of the phosphatic manure to be applied, superphosphate is to be preferred. Potatoes make large demands on potash, and consequently require potassic manures. In consequence of the fact that they receive large applications of farmyard manure, the necessity for adding potash in the form of artificial manures does not generally exist. Potash, if applied in too large quantities, has been found to exert a deleterious effect. We have already pointed out that muriate of potash tends to produce a waxy potato.

The Rothamsted Experiments with Potatoes.

The Rothamsted experimenters have very fully investigated the conditions of the manurial requirements of potatoes. In these experiments potatoes were grown year after year in the same field. It was found that the effect of mineral manures alone was greater than the effect of nitrogenous manures alone, and that of mineral manures phosphates, as a rule, had a better effect than potash; that under the action of the growth of potatoes a greater exhaustion of phosphates than of potash takes place in the soil; and lastly, that it is essential to have an abundant supply of the different fertilising ingredients in order to grow successful crops. In the Rothamsted experiments, the slow action of farmyard manure in supplying fertilising ingredients to the potatoes is strikingly demonstrated. Thus, although farmyard manure was applied at such a rate that more than 200 lb. of nitrogen were added to the soil, the result was inferior to that obtained from the application of 86 lb. of nitrogen applied in the form of readily available artificial manure.

Effect of Farmyard Manure on Potatoes.

It may be said, in this respect, that the potato is less able to utilise the fertilising ingredients of farmyard manure than any other of the farm crops. Yet, despite this fact, farmyard manure has been found to be one of the best manures to apply. The reconciliation of these seemingly contradictory statements depends on the influence exerted by the farmyard manure on the mechanical condition of the soil, rendering it more porous and easily permeable to the surface-roots, upon the development of which the success of the crop so much depends. The beneficial effect of farmyard manure is also doubtless due to the increased temperature which large applications of it produce in a soil.

Sir J. Henry Gilbert, in his well-known Cirencester Lecture on the Growth of Potatoes, cites several examples of the manurial treatment of potatoes in different parts of the country. In Forfarshire, farmyard manure or stable manure is largely employed (at the rate of 12 to 14 tons, and in some cases even 20 tons per acre), and it is also largely supplemented by artificial manures. These latter are applied to the extent of about 10 cwt., and consist of superphosphate, dissolved bones, and potash salts. Six tons of potatoes are considered a fair crop. In East Lothian the manuring is similar, with the exception that farmyard manure is applied in even larger quantities—30 to 40 tons being often used. Sometimes potatoes are grown with artificial manures alone. It would seem that the usual crop of potatoes ranges from 4 to 8 tons per acre.

Manuring of Potatoes in Jersey.

The manuring of the potato crop, so largely grown in Jersey in the Channel Islands, is of interest. Potatoes are there grown two or three years, then corn, then grass for a few years, then potatoes again, no special rotation of crops being followed. Either farmyard manure or sea-weed is applied at the rate of 25 to 30 tons per acre, supplemented by 8 to 12 cwt. of artificial manures.

These statements show how prevalent the practice of heavily manuring the potato crop is.

The Influence of Manure on the Composition of the Potato.

The influence of manure on the composition of the potato crop is of much interest. Potatoes grown without manure, just as in the case of roots, are found to have a larger percentage of nitrogen than potatoes grown with manure. The effect of manuring, therefore, is to increase the proportion of starch, which is the most important constituent of the potato. Mineral manures have a greater effect in increasing the percentage of starch than purely nitrogenous manures; but when used together, a still greater increase is obtained than when used singly. The effect of nitrogenous manures on the composition of roots and potatoes is thus seen to be similar. In the case of both crops the effect is to increase the proportion of the characteristic carbohydrate constituent, which in roots is sugar, and in potatoes starch. Potatoes, like roots, are also much influenced by the season. The effect of season and manuring on the potato disease is worthy of notice. Wet seasons are favourable to the development of the disease. It has been found that in a highly nitrogenous manured crop the proportion of diseased tubers is greater than in a non-manured crop.

LEGUMINOUS CROPS.

We have already referred to the manuring of crops of the leguminous class in discussing the manuring of meadows and permanent pasture. It was there pointed out that the tendency of certain manures was to encourage the growth of the leguminous plants of the herbage, while other manures had the effect of encouraging those of the gramineous class. It was pointed out that a manure which had this effect was potash, or any manure which owed its characteristic action to the fact that it supplied potash to the soil or set it free in the soil.

Leguminous Plants benefit by Potash.

This is one of the most important points to notice in manuring leguminous plants. Just as we can say that nitrogenous manures are specially beneficial to cereals, and phosphatic manures to roots, so potash is the special manure for leguminous crops.

Nitrogenous Manures may actually be hurtful.

But we have, further, an even more striking characteristic of leguminous crops to notice. We have seen that, with regard to the crops already discussed, while there are cases in which a fertilising ingredient may be of no value, or may positively exert a hurtful action on the crops, such cases are only exceptional. With regard to leguminous crops, however, we find that almost invariably they derive little or no benefit from the use of artificial nitrogenous manures. And this is all the more striking since they contain large quantities of nitrogen in their composition—twice as much as the cereals. The fact, which has long been noticed with regard to certain members of this class of plants, such as clover, that not only do they contain a large amount of nitrogen, but that by growing them on a soil the soil is largely enriched in this valuable fertilising constituent, has long waited for a satisfactory explanation, which at last has been forthcoming. The discovery that leguminous crops can draw on the boundless store of nitrogen present in the air has done much to clear up the mystery. There are, however, other problems with regard to the growth of leguminous plants which still await solution.

Clover-sickness.

One of these is the fact that land on which a leguminous crop like clover has been growing for a number of years becomes unfit to support its growth any longer. Such a soil is termed "clover-sick"; and many have been the theories put forward to explain the phenomenon, but none of them can be regarded as satisfactory.

The knowledge that leguminous plants have the power of deriving their nitrogen from the air, furnishes us with an economical means of enriching our soils in nitrogen. By growing leguminous crops alternately with cereals, for example, the air should be made to furnish the necessary nitrogenous manure. As a matter of fact, modified forms of such a practice have long been in use—indeed the ordinary rotations of crops are, to a certain extent, adaptations of this practice.

Alternate Wheat and Beans Rotation.

An interesting experiment carried out at Rothamsted may be here cited which illustrates in a striking manner the truth of the above statement. Wheat and the leguminous crop beans were grown alternately. It was found that almost as much wheat (containing nearly as much nitrogen) was yielded in eight crops of wheat so grown as was yielded by sixteen crops of wheat grown consecutively in an adjoining field.

The most commonly cultivated leguminous crops are clover, beans, and peas. Clover having been already discussed, we need only say a word or two on the manuring of beans and peas.

BEANS.

Beans do best on strong land, and, unlike some of the crops considered, do not require a particularly fine tilth. They are generally grown after cereals, and as a rule are sown in spring. More rarely, however, they are sown in autumn. Spring-sown beans take about seven months to come to maturity. They are much affected, like other crops, but to a greater extent, by the nature of the season—a wet season inducing an undue development of straw.

Manure for Beans.

In common practice the manure used for the bean crop is farmyard manure, applied to the soil in autumn after the harvest of the wheat, barley, or other cereal crop grown. So common is this practice, that the belief commonly exists that farmyard manure is necessary for a successful bean crop. But experiments conducted at the Highland Society's Experiment Station at Pumpherston show that full crops of beans may be grown with the aid of artificial manures on soils which have received no application of farmyard manure for ten years.

Relative Value of Manurial Ingredients.

In the Appendix[246] will be found a table giving the results of manurial experiments with the nitrogenous, phosphatic, and potash manures on beans, carried out by Dr A. P. Aitken at the Highland Society's Experiment Station. From these experiments it will be seen that the application of phosphates and nitrogenous manures, either alone or together, exerted a comparatively small effect in increasing the yield of beans compared with that obtained with potash, either alone or combined with phosphates. As Dr Aitken says, "Without potash in the manure, the other two ingredients are of very little use, unless, indeed, the land be very rich in potash."

Gypsum.

Gypsum has a good effect on the bean crop, both on account of the lime it contains, and of its indirect action in setting free potash.

Superphosphate is a much better manure than insoluble phosphates, and similarly, in the few cases where nitrogenous manures are beneficial, the speediest acting are best. Hence nitrate of soda is to be preferred to other nitrogenous manures. When it is applied, it should be applied in small quantities. A slow-acting nitrogenous manure is positively injurious; so also, according to Dr Aitken, is nitrate of soda, applied as a top-dressing to the crop.

Of potash manures, the muriate seems to be more effective than the sulphate.

Effect of Manure on Composition of Crop.

Lastly, we may refer to the effect of manures on the composition of the crop. This is, on the whole, very slight, especially when compared with the effect manures exert on the composition of such crops as turnips or potatoes. It is the quantity and not the quality of the crop which the manure affects in the case of beans.

PEAS.

Peas are not grown to anything like the same extent as beans. As a rule, when they are cultivated it is along with beans, when they are necessarily manured in a similar manner. If grown alone, however, it may be well to point out that peas do best, unlike beans, on light, friable, chalky loam. When grown in clay they tend to develop an undue amount of straw. The effect of season on the crop is similar to that exerted on the bean crop. In conclusion, it may be pointed out that it is alleged that the effect of farmyard manure on peas is to force the straw.

In concluding this chapter a word or two may be said on the manuring of two other crops which are cultivated to a considerable extent in this country—viz., hops and cabbages.

HOPS.

The requirements of the hop crop in the matter of manures are rather singular. It has been pointed out that in the case of most crops quick-acting manures are to be preferred to slow-acting manures. With hops, however, the case is very different; for they require, and cannot be successfully cultivated without, slow-acting manures. Hops are especially benefited by bulky nitrogenous manures—such as shoddy, horn-meal, hide-scraps, hoofs, rape-dust, &c.; and it is only when quick-acting manures are applied along with such slow-acting manures that they will exercise their full influence. It is best to manure hops twice a-year,—in spring with farmyard manure, supplemented by a slow-acting nitrogenous manure, such as shoddy; and again in summer with a more quickly acting manure. The dressings applied to hops are enormous relatively to those used on other farm crops.

CABBAGES.

Cabbages belong to that class of crops known as gross feeders, to which any sort of manure, applied in almost any quantities, does not come amiss. Cabbages grow best on good loams with a well-drained porous subsoil, although they also do well on clay soils. The quantity of fertilising ingredients, especially potash, which a large crop of cabbage removes from the soil is very great. They consequently require large quantities of manure, and are especially benefited by saline manures—such as kainit and common salt—and liberal doses of nitrate of soda, which may be regarded as the most effective of manures for all the cabbage tribe. Farmyard manure may be applied with benefit in larger quantities than it would be applied to any other crop.

FOOTNOTES:

[244] See his Lecture on the Growth of Barley.

[245] Small roots are found to contain a larger proportion of sugar than large roots.

[246] See Note I., p. 530.



APPENDIX TO CHAPTER XXIII.

NOTE I. (p. 526).

EXPERIMENTS ON THE MANURING OF BEANS.

Experiments with beans carried out at the Highland and Agricultural Society's Experiment Station at Pumpherston, showing the effect of potash:—

No. of Bushels dressed plots. Kind of manure. grain, per acre.

27. No manure 2-1/2 12. Phosphate (bone-ash) 5-1/6 18. Nitrate 6-1/4 21. Phosphate and nitrate 5-1/3 22. Potash 26-1/2 17. Potash and phosphate 42-1/3 10. Potash, phosphate, and nitrate 45-1/2 38. Potash, phosphate, nitrate, and gypsum 51



CHAPTER XXIV.

ON THE METHOD OF APPLICATION AND ON THE MIXING OF MANURES.

Having considered the manuring of the different crops, we may now pass on to the consideration of some points in the method of application and on the mixing of manures.

Equal Distribution of Manures.

A most important object in applying manures is to effect equal distribution of the manure in the soil. This is often, however, unusually difficult to do, especially in the case of artificial manures, where the quantity to be spread over a large area of the soil is extremely small. The difficulty in the case of farmyard or other very bulky manure is not so great. In order to overcome this difficulty in the case of artificial manures, it is often advisable to mix them with some such substance as sand, ashes, loam, peat, or salt. The manure is thus diluted in strength, and a very much larger bulk of substance is obtained to work with. Circumstances must decide which of these substances to use. If the soil be a heavy clay, the addition of sand or ashes may have an important mechanical effect in improving its texture; while, on the other hand, if it be a light soil, the addition of peat may improve its mechanical condition. It must also be remembered that peat itself contains a large amount of nitrogen, and thus forms a manure of some value. In using loam or peat to mix with artificial manures, they should be first dried and then riddled; while if ashes be used, they should be previously reduced to a fine state. Wood-ashes, however, must be used with caution, and ought not to be mixed with ammoniacal manures, as they are apt to contain caustic alkali, which would tend to drive off the ammonia in a volatile state.

It has been recommended, in order to save trouble and effect equal distribution, that the manure to be applied should always be made up to the same amount, so that the farmer by experience may ascertain the rate at which to apply it. And here it may be well to say a word or two on the subject of mixing manures—a subject with which the farmer is not always so conversant as it is desirable in the interests of his own pocket he should be.

Mixing Manures.

It is to be feared that not unfrequently indiscriminate mixing may cause very serious loss in the most valuable constituent of a manure. It may be well, therefore, to point out one or two of the causes of the loss that is apt to ensue on the mixing of different kinds of manures together.

As the subject depends for its clear comprehension on certain chemical elementary principles, it may be well for the benefit of non-chemical readers to state these pretty fully.

Risks of Loss in Mixtures.

The risks of loss which may occur from the mixing of artificial manures together may be of different kinds. One is the risk of actual loss of a valuable ingredient through volatilisation; another is the risk of the deterioration of the value of a mixture through change of the chemical state of a valuable ingredient. Undoubtedly the most common and most serious source of loss is the former. Of the three valuable manurial ingredients—nitrogen, phosphoric acid, and potash—only the first is liable to loss by volatilisation, and this generally only when the nitrogen is either in the form of ammonia or nitric acid.

Loss of Ammonia.

Ammonia, when uncombined, is a very volatile gas with a pungent smell, a property which enables its escape from a manure mixture to be very easily detected. It belongs to a class of substances which are known chemically as bases, and which have the power of combining with acids and forming salts. Sulphate of ammonia is a salt formed—as its name indicates—by the union of the base, ammonia, with the acid, sulphuric acid. Now when ammonia unites with sulphuric acid and forms sulphate of ammonia, it is no longer volatile and liable to escape as a gas, but becomes "fixed," as it is called.

Although most salts are more or less stable bodies—not liable to change—if left alone, and not submitted to a high temperature or chemical action, they can be easily decomposed if they are heated or brought into contact with some other substance which will give rise to chemical action. Sulphate of ammonia is a salt that is very easily decomposed. This is due to the fact that its base, ammonia, is very volatile, and not capable of being held very firmly by an acid, even by sulphuric, which is among the least volatile of all the common acids. If, therefore, sulphate of ammonia be heated above the boiling-point of water, or brought in contact with any other substance which will give rise to chemical action, it is easily decomposed. Now a salt may be acted upon by a base or an acid or another salt. When it is brought in contact with a base, if the base with which it is brought in contact be a stronger base than the base of the salt, the salt is decomposed, and a new salt is formed. The acid, in short, exchanges its old base for the new one.

Effect of Lime on Ammonia Salt.

This is exactly what takes place when the base lime comes in contact with an ammonium salt, such as sulphate of ammonia. The sulphuric acid exchanges its old base, ammonia, for the stronger base, lime, and sulphate of lime is formed, and ammonia is set free as a gas, and escapes and is lost. Sulphate of ammonia, or any substance in which there is an ammonia salt, must never be brought in contact with free lime, otherwise the ammonia will be lost, and should be harrowed in on chalky soils for this reason.

It is different entirely with gypsum—which is sulphate of lime—or phosphate of lime, both of which may be safely mixed with sulphate of ammonia without any danger of escape of ammonia. It follows from the above that a mixture which must on no account be tried is slag phosphate and sulphate of ammonia. This is because the slag phosphate contains a large percentage of free lime, which would at once, on being brought in contact with the sulphate of ammonia, decompose it, and cause the ammonia to be lost. For this same reason guano must not be mixed with slag. It is perhaps unnecessary, however, to warn one against so doing, as it is not likely such a mixture would be made, as the ratio of phosphoric acid to nitrogen in guanos is generally greater than is required. If it be desired to mix the slag with a quickly available form of nitrogen, nitrate of soda is not liable to loss; although for other reasons it is not desirable to apply nitrate of soda along with the slag, as the former manure should be applied almost always as a top-dressing.

Loss of Nitric Acid.

The risks of the loss of nitrogen in the form of nitric acid, although not so great as they are in the case of ammonia, are still considerable. As nitric acid is not a base but an acid, what is to be avoided in mixing nitrates is bringing them in contact with any other manure which contains another free and stronger acid—as, for example, superphosphate. The free acid present in superphosphate has the tendency to drive out the nitric acid from the nitrate and usurp its place. The risk of loss of expulsion in the above cases is always augmented by the rise of temperature which invariably accompanies chemical action of any kind; and although the loss of nitrogen, in the form of nitric acid, caused by mixing superphosphate and nitrate of soda, might, under ordinary circumstances, amount to very little, yet, if the mixture were to be allowed to stand any time, and the temperature of the mass to be heightened, the loss which would undoubtedly then ensue would be considerable.

The nitrogen salt which it is safe to mix with superphosphate is sulphate of ammonia.

Reversion of Phosphates.

But, as has already been mentioned, there is another loss which may result from the mixing of manures. This is the deterioration of the value of an ingredient by reason of change of chemical condition. This is a source of loss that was little suspected a number of years ago, but it is now well known that superphosphate of lime, under certain conditions, is changed from its soluble to an insoluble form. We have already referred to the reversion of phosphate in the chapter on the Manufacture of Superphosphates.[247] It was there pointed out that reversion is often caused by the presence of iron and alumina or undissolved phosphate, and that the risk of reversion is therefore very much less in a well-made article, made from pure raw material, than in one made from a raw phosphate containing much iron and alumina. Superphosphates containing a large percentage of insoluble phosphates ought not to be kept too long before being used as a manure, otherwise much of the labour and expense involved in their manufacture will be lost by the reversion of their soluble phosphate. Further, it is highly inadvisable to mix superphosphates with basic slag, which contains a large percentage of both iron and free lime. Lastly, if it is desired to mix superphosphate with insoluble phosphate, the mixture ought to be made just previous to application.

Manurial Ingredients should be applied separately.

The question of applying manure in mixtures is one on which considerable difference of opinion may exist. For many reasons manures are often better applied in the unmixed condition. For example, a mixture of a quickly acting nitrogenous manure with a slowly acting phosphatic manure is not suitable. In such a case either the nitrogenous manure will be applied too long before it is required by the plant, and thus suffer from risk of loss, or the phosphatic manure will not be applied long enough before it is likely to be used. By applying manures in an unmixed condition the chances are that a more economical use of them is made than would otherwise be the case. On the other hand, while the application of the separate constituents may be desirable from the scientific point of view, it involves a considerable amount of extra trouble. Of course a further consideration is the desirability in many cases of having a complete manure. The above hints, therefore, on the risks of loss which exist in mixing manures, may be of service to the agricultural student.

FOOTNOTES:

[247] See p. 389.



CHAPTER XXV.

ON THE VALUATION AND ANALYSIS OF MANURES.

Value of Chemical Analysis.

The value of a manure to the farmer depends on the proportion of nitrogen, phosphoric acid, and potash it contains, as well as—and this is hardly less important—the condition in which the ingredients are present. Since these facts can alone be determined by a chemical analysis, it is obvious that manures should always be purchased with a chemical analysis. It is unfortunate, however, that very often a chemical analysis, even when procured, is unintelligible. It may be of advantage, therefore, to say a word or two on the correct interpretation of the significance of the data furnished in the ordinary chemical analysis of manures.

Interpretation of Chemical Analysis.

The first thing that the farmer ought to look for in the analysis of a manure is the amount of nitrogen, phosphoric acid, and potash which the manure contains.

Nitrogen.

The percentage of nitrogen in a manure is generally stated as equal to its equivalent percentage of ammonia. Very often, indeed, in the older analyses, its equivalent of ammonia was alone stated. Now this statement does not necessarily imply that the nitrogen in a manure is actually present in the form of ammonia. Thus, for example, when it is stated in an analysis of bone-meal that it contains 3.5 per cent of nitrogen, equal to 4.20 per cent of ammonia, it is not to be inferred that bone-meal actually contains nitrogen in the form of ammonia. In point of fact the nitrogen is present in an insoluble, slowly available, organic form, which possesses a manurial value very inferior to that possessed by ammonia. This custom is a most unfortunate one, and is much to be regretted, as it is often liable to give rise to serious misunderstanding. It must be remembered, therefore, that an ordinary chemical analysis does not always specify the exact form in which nitrogen is actually present. It is nevertheless of importance for the farmer to know this, of which the nature of the manure analysed is generally a good indication. Unfortunately this is not shown in the case of mixed manures; and this constitutes one of the reasons why mixed manures are sometimes to be regarded with suspicion.

Phosphoric Acid.

The amount of phosphates present in a manure is usually stated in its analysis as so much phosphoric acid, while in a footnote the quantity of tricalcic (or ordinary bone) phosphate this amount is equivalent to is also given, this being the unit of valuation. When the phosphates are in a soluble condition they are stated as such, and at the same time a statement is made as to the quantity of tricalcic phosphate which would be required to furnish this amount by treatment with sulphuric acid. Thus, for example, in an analysis of a superphosphate of lime, the statement, monocalcic phosphate, 17.3 per cent, equal to tricalcic phosphate rendered "soluble," 27.2 per cent, means that it would require 27.2 per cent of tricalcic phosphate to furnish 17.3 per cent of soluble phosphate. Paradoxically enough, the former amount is called "soluble" phosphate, and such a superphosphate as the above would be described as containing 27.2 per cent of "soluble" phosphate.

Again, there are different forms of the so-called "insoluble" phosphates,[248] although they are often not distinguished in a chemical analysis. As we have already pointed out in the chapter on Basic Slag, phosphoric acid occurs in the slag in the form of tetrabasic phosphate of lime, although it is invariably stated in analysis as so much tricalcic phosphate. Then we have the so-called dibasic phosphate of lime, the form into which soluble phosphate in superphosphate is converted when "reversion" takes place. Hitherto it has not been customary in this country—although the custom is prevalent both on the Continent and in America—to distinguish in the analysis of a superphosphate the "reverted" phosphate from the undissolved phosphate; since the superior value of the former as a manure is not recognised in the manure-trade.[249]

Importance of Mechanical Condition of Phosphate.

A further point to which it is desirable to draw attention is the mechanical condition of the different insoluble phosphates, which has an important influence on their value. A very wide difference, for example, exists between the value of phosphate of lime in such a manure as Malden guano and in the crystalline mineral apatite; although, chemically considered, the form in which the phosphoric acid is present is the same in both substances.

Potash.

Potash ought only to occur in a soluble form in manures. It is generally stated as so much potash, and in a footnote the equivalent amount of muriate or sulphate of potash is given, the former being the more concentrated form of potash.

For purposes of reference a table will be found in the Appendix[250] giving some useful factors for converting different forms of nitrogen, phosphoric acid, and potash into one another.

Other Items in the Chemical Analysis of Manures.

The other items in the analysis of a manure are of comparatively secondary importance compared with those already named. Among them may be mentioned the moisture, the insoluble matter, and the organic matter. The amount of moisture and the amount of sand are two items of importance, since, if these are excessive, they afford presumption that the manure has been adulterated.

Fertilisers and Feeding Stuffs Act.

An Act was passed, and came into operation in January 1894, for the purpose of compelling every vendor of manure manufactured in this country or imported from abroad to give to the purchaser "an invoice stating the name of the article, and whether it is an artificially compounded article or not, and what is at least the percentage of the nitrogen, soluble and insoluble phosphates, and potash, if any, contained in the article, and this invoice shall have the same effect as a warranty by the seller of the statements contained therein."

Different Methods of Valuing Manures.

The monetary value of a manure depends upon a number of more or less complicated commercial considerations, such as the questions of supply and demand, &c., which need not here be discussed, and which similarly regulate the monetary value of any other article of commerce.

"Unit" Value of Manurial Ingredients.

For the purpose of affording data for ascertaining the approximate value of a manure, tables have been drawn up giving what is called the "unit" value of the different manurial ingredients in various manures. This is obtained by dividing the market value of a manure per ton by the percentage of nitrogen, phosphoric acid, and potash it contains. Thus, for example, sulphate of ammonia of 97 per cent purity contains 25 per cent of ammonia, and at present (Dec. 1893) is valued at L13, 15s. per ton. In order to obtain the unit value of ammonia in sulphate of ammonia, we have only to divide L13, 15s. by 25, which gives us 11s. The value of such tables depends on the competence of those drawing them up, and they require to be subjected to constant revision. In the Appendix will be found two of these tables, taken from the 'Transactions of the Highland and Agricultural Society of Scotland.'[251]

Intrinsic Value of Manures.

But there is another way of valuing manures, and that is by attempting to ascertain what their intrinsic worth is in producing an increase in the returns of the crops. Of course it may be said that the intrinsic worth of manure affects directly its market value. This is doubtless true, but it is not the only factor in determining the market value of a manure.

Again, the intrinsic worth of a manure may be said to vary according to the soil to which it is applied and the climatic conditions. This being so, it is important for every farmer to try and ascertain for himself what the intrinsic value of different manures is on the soil of his farm; and this can only be done by carrying out manuring experiments for himself. This leads us to say a word or two on the important subject of

Field Experiments.

It is impossible that every farm should be able to support an experiment station for the purpose of carrying out elaborate experiments on the effect of different manures on different crops. Nevertheless it is possible and highly desirable for every farmer who is engaged in arable farming on any scale to carry out simple experiments for the purpose of ascertaining the characteristic manurial requirements of his soil. This can be done at the expenditure of a little time and trouble, and should be carried out in the following way. The field on which it is desired to carry out the experiments should be divided into the requisite number of experiment plots. These, which may be the tenth, twentieth, or fortieth of an acre in extent, should be, if possible, on a level piece of ground—all of them equally free from the shelter of hedge or tree, and otherwise subjected to the same conditions. The nature of the soil of the different plots, as well as its past treatment, should be similar. It is desirable, in order to minimise experimental error as much as possible, to carry out the experiments in duplicate, or even triplicate. In the first place, there should be what is called a nothing plot—i.e., a plot receiving no manure. The produce obtained from this plot, compared with the produce obtained from the other manured plots, will thus furnish data for estimating the respective amounts of increase obtained by different manures. One very simple kind of experiment is what is called the "seven-plot" test. It consists in testing the results obtained by using nitrogenous, phosphatic, and potash manures alone and in different combinations. Thus the plots would be manured respectively as follows:—

No. No. 1. Nothing plot. 5. Nitrogen and phosphates. 2. Nitrogen. 6. Nitrogen and potash. 3. Phosphates. 7. Phosphates and potash. 4. Potash.

The subjects of other experiments might be such as the respective values of nitrogen in the different forms of sulphate of ammonia and nitrate of soda; phosphoric acid as superphosphate, and in an undissolved form as Thomas-slag; the relative importance of artificial and farmyard manure; the effect of manures applied at different times, as well as the effect of different quantities of the same manure; the most economical manures for different kinds of crops; and numerous other interesting problems connected with the practical application of manures.

In carrying out these experiments, care should be taken not to have the experimental plots immediately adjoining one another, as the manure applied to the one plot may, by soaking through the soil, affect the result on the adjoining plot. Especial note ought to be taken of the weather during the progress of the experiment. In order to make such experiments as valuable as possible, they ought to be continued year after year. At the conclusion of the experiment the produce obtained from each plot should be carefully weighed.

Educational Value of Field Experiments.

The educative value of such experiments is very great, and in this connection the remarks made by Mr F. J. Cooke, in a recent lecture delivered to the London Farmers' Club, are worthy of most careful consideration.

"Local experiments," he says, "teach the simple principles which should determine the selection of manures, as well as scientific accuracy and method in their use. The value of experiments is thus brought home to men who would not go far to discover it; and the practice of a few simple trials upon a correct system, each on his own farm, is encouraged. That such trials may be conducted with very little expense to the farmer, or other difficult qualifications, and yet to his great practical advantage, I will venture to assert on the ground of my own personal experience. For some twenty years I have annually conducted private experiments on a very humble scale, and am not aware of any other separate practice which has been so useful to me. It has been pursued upon two light-land farms in different parts of the same county. Yet, in respect of manurial requirements, the proper treatment for one of them has differed so essentially from the other that a common practice upon both would have been simply ruinous."

Value of Manures deduced from Experiments.

Tables have been constructed for the purpose of showing the comparative value of different kinds of manures as deduced from such experiments, and may be fittingly compared with the tables giving the trade prices. We have already quoted some of these tables in the Appendix to the chapter on Mineral Phosphates. These tables show the relative intrinsic value of different forms of phosphatic manures. In the Appendix[252] to this chapter tables showing the relative value of different kinds of nitrogenous and potash manures will be found.

Value of Unexhausted Manures.

A subject which has had much attention devoted to it of late years is the question of the value of unexhausted manures in the soil. In the Agricultural Holdings Act special provision is made for giving compensation to the out-going tenant of a farm for unexhausted manures in the soil. The Act has given rise to endless disputes between landlord and tenant, owing to the extreme difficulty of arriving at a satisfactory estimate of what the value of the unexhausted manures in reality is. The difficulty arises from the fact that we have not sufficient data available for guiding us in estimating this value, which further varies under different conditions. The fertilising ingredients of a soil are present in the soil for the most part in an inert condition, from which they are only slowly converted into an available form.

Potential Fertility of a Soil.

As indicating the total amount of the more important mineral ingredients present in a soil, it may be mentioned that it has been calculated, in the case of a poor sandy soil, that the amount of potash it contains (provided it were in an available condition) would be sufficient to yield three or four average crops of potatoes; of phosphates, nineteen average crops; and of lime, seventy-three. But then only a very small amount of this fertilising matter is in a readily available form.

It is for this reason that artificial manures, although added in such small amounts, exercise so striking an influence in increasing plants' growth. Their effect, however, is to a large extent only of a temporary nature; and in attempting to assess the unexhausted value of a manure a year or two after its application, we must remember this fact.

Some manures are very speedily taken up by plants, and some are very easily washed out of the soil. Others, again, it would seem highly probable, have a tendency to become converted into a more or less inert condition after a while. This remark may be especially applied to the fertilising constituents (chiefly nitrogen) in farmyard manure.[253] The whole question, however, is little understood. One or two points may be drawn attention to. In the first place, it may be safely affirmed that little direct effect can be expected from such quickly available and easily soluble forms of nitrogenous manures as nitrate of soda and sulphate of ammonia a year after application. Potash and phosphates, on the other hand, may exercise an effect for a considerably longer period; and what the length of this period may be will depend on their amount and condition. Thus it is not likely that superphosphate will have much effect more than two years after application. On the other hand, such manures as bones, basic slag, and farmyard manure may exert an appreciable influence for a number of years. How long exactly, it is wellnigh impossible to say, the rate at which they are applied and the nature of the soil having an important influence.

Tables of Value of Unexhausted Manures.

Numerous tables have been drawn up for the purpose of guiding farmers in estimating this unexhausted value at different periods after application, and in the case of different manures. Such tables, as a rule, furnish only very rough approximations, and are little better than mere guess-work. Still more complicated is the attempt to assess the manurial value of foods consumed by the stock of the farm. Lawes and Gilbert have devoted much attention to the elucidation of this difficult question, and have drawn up most elaborate and valuable tables, furnishing data for calculating unexhausted manure value in the case of commonly used foods. These tables are given in the Appendix.[254] In them will be found the manurial value of different cattle-foods, calculated on the basis of numerous experiments carried out at Rothamsted.

Thus these experiments have demonstrated that, on an average, probably not more than one-tenth of the nitrogen, phosphoric acid, and potash a food contains is removed from the food in its passage through the animal system. The exact amount will obviously depend on a variety of conditions, referred to already in a previous chapter.[255]

In explanation of these tables, it may be pointed out that Table I. gives the total quantities of the three fertilising ingredients in various foods; while Table II. shows the proportion retained in the animal body and the proportion voided in the manure, as well as the manurial value of the food, assuming that it exercises its full theoretical effect. As this, however, is never fully realised, it is necessary to make some deduction. The deduction suggested by the Rothamsted experimenters, on the basis of their wide experience, is 50 per cent for food consumed within the last year. That is to say, the manurial value of food consumed during the last year is only one-half its theoretical value. For food consumed within the last year but one, they suggest a deduction of one-third of the allowance for last year; while for food consumed three years back, a deduction of one-third from this latter sum should be made; and so on for whatever number of years, down to eight, may be taken.

FOOTNOTES:

[248] The term insoluble phosphates is an unfortunate one, as the word insoluble is purely relative in its significance. Undissolved phosphates would be a better term.

[249] The amount of "reverted" phosphate is estimated by the ammonium citrate process.

[250] See Note I., p. 553.

[251] See Note II., p. 554.

[252] See Note III., p. 556.

[253] See Chapter on Farmyard Manure, p. 271.

[254] See Note IV., p. 557.

[255] See Chapter on Farmyard Manure, pp. 224-236.



APPENDIX TO CHAPTER XXV.

NOTE I. (p. 543).

USEFUL FACTORS FOR CALCULATING THE PERCENTAGE OF IMPORTANT MANURIAL INGREDIENTS IN A MANURE INTO THEIR DIFFERENT COMPOUNDS. (From the 'Transactions of the Highland and Agricultural Society.')

Multiplied Gives corresponding Amount of by amount of Nitrogen 1.214 Ammonia. " 6.3 Albuminoid matter. Ammonia .824 Nitrogen. " 3.882 Sulphate of ammonia. " 3.147 Muriate of ammonia. " 3.706 Nitric acid. " 5.0 Nitrate of soda. Potash (anhydrous) 1.85 Sulphate of potash. " 1.585 Muriate of potash. Phosphoric acid (anhydrous) 2.183 Phosphate of lime. " " 1.4 Biphosphate. " " 1.648 Soluble phosphate. Soluble phosphate 1.325 Phosphate of lime. Biphosphate 1.566 " Lime 1.845 " " 1.786 Carbonate of lime. Chlorine 1.648 Chloride of sodium.

NOTES II. (p. 545).

UNITS TO BE USED IN DETERMINING THE COMMERCIAL VALUE OF MANURES.

For Season 1893.

A: Ichaboe. B: Peruvian (riddled). C: Fish guano. D: Frey Bentos guano. E: Steamed bone-flour. F: Dissolved or vitriolated bones. G: Superphosphates. H: Genuine. I: Genuine. J: Average.

-+ -+ -+ -+ Guanos. Scrap manures. Items to be + -+ -+ -+ -+ Bone-meal. valued. A B C D -+ -+ -+ -+ -+ -+ -+ -+ Classes H I a. b. a. b. -+ -+ -+ -+ -+ -+ -+ -+ Phosphates Dissolved - - - - - - - Undissolved 2/- 2/- 1/5 1/6 1/4 1/4 1/3 Ammonia 16/- 17/6 10/- 11/6 10/- 10/- 9/6 Potash - 3/6 - - - - - Prices per ton, March 1893 From 250/- 230/- 130/- 150/- 120/- 105/- 100/- To 270/- 290/- 150/- 180/- 140/- 115/- 110/- -+ -+ -+ -+ -+ -+ -+ -+

- - - - - Items to be E F G Dissolved valued. Compounds. - - - - - - - Classes a. From To J - - - - - - - Phosphates Dissolved - 2/6 - 2/- 2/6 2/3 Undissolved 1/5 1/6 1/11 1/3 1/9 1/6 Ammonia 10/- 11/6 - 10/- 12/- 11/- Potash - - - 3/4 3/8 3/6 Prices per ton, March 1893 From 95/- 95/- 45/- - - - To 110/- 110/- 60/- - - - - - - - - - -

CASH PRICES OF DIFFERENT MANURES, MARCH 1893.

-+ -+ + Price per MANURES. Guarantee. ton. Unit. -+ -+ + Per cent. L s. d. Sulphate of ammonia, 97 per cent 24 Am. 11 10 0 Am. = 9/7 Nitrate of soda, 95 per cent 19 " 10 5 0 " = 10/9 Castor-cake dust 5.5 " 3 10 0 " = 12/9 Horn-dust 15 " 8 10 0 " = 11/4 Dried blood 15 " 8 0 0 " = 10/7 Muriate of potash, 80 per cent 50 Pot 8 15 0 Pot.= 3/6 Sulphate of potash, 50 per cent 27 " 5 5 0 " = 3/10 Kainit, 23 per cent 12 " 2 0 0 " = 3/4 Nitrate of potash, 73 per cent {14 Am.} 14 10 0 {Am. = 10/} {40 Pot.} {Pot.= 3/9} Ground Charleston phosphate 57 Phos. 3 0 0 Phos.=1/ Belgian phosphate 50 " 2 5 0 " = 0/11 Thomas-slag (fine) Scotch 30 " 1 16 0 " = 1/2 Thomas-slag (fine) English 37 " 2 3 0 " = 1/2 Phosphatic guano {67 " } 5 0 0 {" = 1/4} {1 Am. } {Am. = 10/} -+ -+ +

NOTE III. (p. 549).

TABLES SHOWING RELATIVE MANURIAL VALUE OF NITROGEN AND POTASH IN DIFFERENT SUBSTANCES.

Wolff, 1893.

Nitrogen in form of ammonia and nitrates, and easily decomposable organic compounds, as dried blood, flesh-meal, meat-meal, Peruvian guano, and as urate 100 " in fine steamed bone-meal, fish-guano, oilcakes, and better kinds of artificial guano 85 " in fine bone-meal and horn-meal 77 " in coarse bones and horn-shavings, woollen refuse, farmyard manure, and poudrette 61

American, 1892.

" in ammonia salts 100 " as nitrates 86 " in dry and fine-ground fish, meat, and blood 91 " in cotton-seed meal, and castor pomace 86 " in fine bone and tankage 86 " in medium bone and tankage 68 " in coarser bone and tankage 43 " in hair and horn-shavings, and coarse fish scrap 40 Potash as high-grade sulphate, and in forms free from muriates (or chlorides) 100 " as muriate 82

Professor Wagner has drawn up, from numerous experiments, the relative manurial values of different nitrogenous manures, which he rates as follows:—

Nitrate of soda 100 Sulphate of ammonia 90 Blood-meal, horn-meal, and green vegetable matter 70 Finely ground steamed bone-meal, fish-meal, and meat-meal guano 60 Farmyard manure 45 Shoddy 30 Leather-meal 20

NOTE IV. (p. 551).

TABLE I.—AVERAGE COMPOSITION, PER CENT AND PER TON, OF CATTLE-FOODS.

-+ -+ -+ PER CENT. NO. FOODS. + -+ + -+ + -+ Dry Nitro- Mineral Phos- Potash. Matter. gen. Matter phoric (Ash). Acid -+ -+ -+ + -+ + -+ per per per per per cent. cent. cent. cent. cent. 1 Linseed 90.00 3.60 4.00 1.54 1.37 2 Linseed-cake 88.50 4.75 6.50 2.00 1.40 3 Decorticated cotton cake 90.00 6.60 7.00 3.10 2.00 4 Palm-nut-cake 91.00 2.50 3.60 1.20 0.50 5 Undecorticated cotton-cake 87.00 3.75 6.00 2.00 2.00 6 Cocoa-nut-cake 90.00 3.40 6.00 1.40 2.00 7 Rape-cake 89.00 4.90 7.50 2.50 1.50 -+ -+ -+ + -+ + -+ 8 Peas 85.00 3.60 2.50 0.85 0.96 9 Beans 85.00 4.00 3.00 1.10 1.30 10 Lentils 88.00 4.20 4.00 0.75 0.70 11 Tares (seed) 84.00 4.20 2.50 0.80 0.80 -+ -+ -+ + -+ + -+ 12 Indian corn 88.00 1.70 1.40 0.60 0.37 13 Wheat 85.00 1.80 1.70 0.85 0.53 14 Malt 94.00 1.70 2.50 0.80 0.50 15 Barley 84.00 1.65 2.20 0.75 0.55 16 Oats 86.00 2.00 2.80 0.60 0.50 17 Rice-meal* 90.00 1.90 7.50 (0.60) (0.37) 18 Locust-beans* 85.00 1.20 2.50 - - -+ -+ -+ + -+ + -+ 19 Malt-combs 90.00 3.90 8.00 2.00 2.00 20 Fine pollard 86.00 2.45 5.50 2.90 1.46 21 Coarse pollard 86.00 2.50 6.40 3.50 1.50 22 Bran 86.00 2.50 6.50 3.60 1.45 -+ -+ -+ + -+ + -+ 23 Clover-hay 83.00 2.40 7.00 0.57 1.50 24 Meadow-hay 84.00 1.50 6.50 0.40 1.60 -+ -+ -+ + -+ + -+ 25 Pea-straw 82.50 1.00 5.50 0.35 1.00 26 Oat-straw 83.00 0.50 5.50 0.24 1.00 27 Wheat-straw 84.00 0.45 5.00 0.24 0.80 28 Barley-straw 85.00 0.40 4.50 0.18 1.00 29 Bean-straw 82.50 0.90 5.00 0.30 1.00 -+ -+ -+ + -+ + -+ 30 Potatoes 25.00 0.25 1.00 0.15 0.55 31 Carrots 14.00 0.20 0.90 0.09 0.28 32 Parsnips 16.00 0.22 1.00 0.19 0.36 33 Swedish turnips 11.00 0.25 0.60 0.06 0.22 34 Mangel-wurzels 12.50 0.22 1.00 0.07 0.40 35 Yellow turnips* 9.00 0.20 0.65 (0.06) (0.22) 36 White turnips 8.00 0.18 0.68 0.05 0.30 -+ -+ -+ + -+ + -+

-+ -+ - PER TON. + -+ -+ - NO. FOODS. Nitrogen. Phos- Potash. phoric Acid -+ -+ -+ -+ - lb. lb. lb. 1 Linseed 80.64 34.50 30.69 2 Linseed-cake 106.40 44.80 31.36 3 Decorticated cotton cake 147.84 69.44 44.80 4 Palm-nut-cake 56.00 26.88 11.20 5 Undecorticated cotton-cake 84.00 44.80 44.80 6 Cocoa-nut-cake 76.16 31.36 44.80 7 Rape-cake 109.76 56.00 33.60 -+ -+ -+ -+ - 8 Peas 80.64 19.04 21.50 9 Beans 89.60 24.64 29.12 10 Lentils 94.08 16.80 15.68 11 Tares (seed) 94.08 17.92 17.92 -+ -+ -+ -+ - 12 Indian corn 38.08 13.44 8.29 13 Wheat 40.32 19.04 11.87 14 Malt 38.08 17.92 11.20 15 Barley 36.96 16.80 12.32 16 Oats 44.80 13.44 11.20 17 Rice-meal* 42.56 (13.44) (8.29) 18 Locust-beans* 26.88 - - -+ -+ -+ -+ - 19 Malt-combs 87.36 44.80 44.80 20 Fine pollard 54.88 64.96 32.70 21 Coarse pollard 56.00 78.40 33.60 22 Bran 56.00 80.64 32.48 -+ -+ -+ -+ - 23 Clover-hay 53.76 12.77 33.60 24 Meadow-hay 33.60 8.96 35.84 -+ -+ -+ -+ - 25 Pea-straw 22.40 7.84 22.40 26 Oat-straw 11.20 5.38 22.40 27 Wheat-straw 10.08 5.38 17.92 28 Barley-straw 8.96 4.03 22.40 29 Bean-straw 20.16 6.72 22.40 -+ -+ -+ -+ - 30 Potatoes 5.60 3.36 12.32 31 Carrots 4.48 2.02 6.27 32 Parsnips 4.93 4.26 8.06 33 Swedish turnips 5.60 1.34 4.93 34 Mangel-wurzels 4.93 1.57 8.96 35 Yellow turnips* 4.48 (1.34) (4.93) 36 White turnips 4.03 1.12 6.72 -+ -+ -+ -+ - * In the case of neither rice-meal, locust-beans, nor yellow turnips have records of ash analyses been found. For rice-meal the same percentages of phosphoric acid and potash as in Indian corn, and for yellow turnips the same as in swedes, are provisionally adopted; but in all the Tables the assumed results are given in parentheses. For locust-beans no figure has been assumed, and the columns are left blank.

NOTE IV.

TABLE II.—LAWES' & GILBERT'S TABLES FOR CALCULATING UNEXHAUSTED VALUE OF MANURES.

KEY: A - Fattening Increase in Live Weight (Oxen or Sheep). B - In Food. C - In Fattening Increase (at 1.27 per cent). D - In Manure. E - Food to 1 Increase. F - Increase per ton of Food. G - Per cent. H - Per ton. I - From 1 ton of Food. J - Per cent of total consumed. K - Total remaining for Manure. L - Nitrogen equal Ammonia. M - Value of Ammonia at 6d per lb.

-+ -+ -+ + NITROGEN. + -+ - A B C D DESCRIPTION -+ -+ -+ + -+ -+ + -+ NO. OF FOOD. E F G H I J K L M -+ -+ -+ -+ -+ + -+ -+ + -+ + lb. % lb. lb. % lb. lb. L s. d. 1 Linseed 5.0 448.0 3.60 80.64 5.69 7.06 74.95 91.0 2 5 6 2 Linseed-cake 6.0 373.3 4.75 106.40 4.74 4.45 101.66 123.4 3 1 8 3 Decorticated cotton-cake 6.5 344.6 6.60 147.84 4.38 2.96 143.46 174.2 4 7 1 4 Palm-nut-cake 7.0 320.0 2.50 56.00 4.06 7.25 51.94 63.1 1 11 7 5 Undecorticated cotton-cake 8.0 280.0 3.75 84.00 3.56 4.24 80.44 97.7 2 8 10 6 Cocoa-nut-cake 8.0 280.0 3.40 76.16 3.56 4.67 72.60 88.2 2 4 1 7 Rape-cake (10) (224) 4.90 109.76 2.84 2.59 106.92 129.8 3 4 11 -+ -+ -+ + -+ -+ + -+ + 8 Peas 7.0 320.0 3.60 80.64 4.06 5.03 76.58 93.0 2 6 6 9 Beans 7.0 320.0 4.00 89.60 4.06 4.53 85.54 103.9 2 11 11 10 Lentils 7.0 320.0 4.20 94.08 4.06 4.32 90.02 109.3 2 14 8 11 Tares (seed) 7.0 320.0 4.20 94.08 4.06 4.32 90.02 109.3 2 14 8 -+ -+ -+ + -+ -+ + -+ + 12 Indian corn 7.2 311.1 1.70 38.08 3.95 10.37 34.13 41.4 1 0 9 13 Wheat 7.2 311.1 1.80 40.32 3.95 9.80 36.37 44.2 1 2 1 14 Malt 7.0 320.0 1.70 38.08 4.06 10.66 34.02 41.3 1 0 8 15 Barley 7.2 311.1 1.65 36.96 3.95 10.69 33.01 40.1 1 0 1 16 Oats 7.5 298.7 2.00 44.80 3.79 8.46 41.01 49.8 1 4 11 17 Rice-meal 7.5 298.7 1.90 42.56 3.79 8.91 38.77 47.1 1 3 6 18 Locust-beans 9.0 248.9 1.20 26.88 3.16 11.76 23.72 28.8 0 14 5 -+ -+ -+ + -+ -+ + -+ + 19 Malt-combs 8.0 280.0 3.90 87.36 3.56 4.08 83.80 101.8 2 10 11 20 Fine pollard 7.5 298.7 2.45 54.88 3.79 6.91 51.09 62.0 1 11 0 21 Coarse pollard 8.0 280.0 2.50 56.00 3.56 6.35 52.44 63.7 1 11 10 22 Bran 9.0 248.9 2.50 56.00 3.16 5.64 52.84 64.2 1 12 1 -+ -+ -+ + -+ -+ + -+ + 23 Clover-hay 14.0 160.0 2.40 53.76 2.03 3.78 51.73 62.8 1 11 5 24 Meadow-hay 15.0 149.3 1.50 33.60 1.90 5.65 31.70 38.5 0 19 3 -+ -+ -+ + -+ -+ + -+ + 25 Pea-straw 16.0 140.0 1.00 22.40 1.78 7.95 20.62 25.0 0 12 6 26 Oat-straw 18.0 124.4 0.50 11.20 1.58 14.11 9.62 11.7 0 5 10 27 Wheat-straw 21.0 106.7 0.45 10.08 1.36 13.49 8.72 10.6 0 5 4 28 Barley-straw 23.0 97.4 0.40 8.96 1.24 13.84 7.72 9.4 0 4 8 29 Bean-straw 22.0 101.8 0.90 20.16 1.29 6.39 18.87 22.9 0 11 6 -+ -+ -+ + -+ -+ + -+ - + 30 Potatoes 60.0 37.3 0.25 5.60 0.47 8.39 5.13 6.2 0 3 1 31 Carrots 85.7 26.1 0.20 4.48 0.33 7.37 4.15 5.0 0 2 6 32 Parsnips 75.0 29.9 0.22 4.93 0.38 7.71 4.55 5.5 0 2 9 33 Swedish turnips 109.1 20.5 0.25 5.60 0.26 4.64 5.34 6.5 0 3 3 34 Mangel-wurzels 96.0 23.3 0.22 4.93 0.30 6.09 4.63 5.6 0 2 10 35 Yellow turnips 133.3 16.8 0.20 4.48 0.21 4.69 4.27 5.2 0 2 7 36 White turnips 150.0 14.9 0.18 4.03 0.19 4.71 3.84 4.7 0 2 4 -+ -+ -+ -+ -+ + -+ -+ + -+ +



KEY: N - In Food. O - In Fattening Increase at (0.86 per cent). P - In Manure. Q - In Food. R - In Fattening Increase at (0.11 per cent). S - In Manure. T - Per cent. U - Per ton. V - From 1 ton of Food. W - Per cent of total consumed. X - Total remaining for Manure. Y - Value at 3d per lb. Z - Per cent. AA - Per ton. BB - From 1 ton of Food. CC - Per cent of total consumed. DD - Total remaining for Manure. EE - Value at 2-1/2d. per lb. FF - Total original Manure value per ton of Food consumed.

-+ -+ + PHOSPHORIC ACID. -+ + + + N O P Description + -+ + -+ -+ + No. of Food. T U V W X Y -+ -+ + -+ + -+ -+ + % lb. lb. % lb. s. d. 1 Linseed 1.54 34.50 3.85 11.16 30.65 7 8 2 Linseed-cake 2.00 44.80 3.21 7.17 41.59 10 5 3 Decorticated cotton-cake 3.10 69.44 2.96 4.26 66.48 16 8 4 Palm-nut-cake 1.20 26.88 2.75 10.23 24.13 6 0 5 Undecorticated cotton-cake 2.00 44.80 2.41 5.38 42.39 10 7 6 Cocoa-nut-cake 1.40 31.36 2.41 7.68 28.95 7 3 7 Rape-cake 2.50 56.00 1.93 3.45 54.07 13 6 + -+ + -+ -+ - + 8 Peas 0.85 19.04 2.75 14.44 16.29 4 1 9 Beans 1.10 24.64 2.75 11.10 21.89 5 6 10 Lentils 0.75 16.80 2.75 16.37 14.05 3 6 11 Tares (seed) 0.80 17.92 2.75 15.36 15.17 3 9 + -+ + -+ -+ - + 12 Indian corn 0.60 13.44 2.68 19.94 10.76 2 8 13 Wheat 9.85 19.04 2.68 14.08 16.36 4 1 14 Malt 0.80 17.92 2.75 15.35 15.17 3 9 15 Barley 0.75 16.80 2.68 15.95 14.12 3 6 16 Oats 0.60 13.44 2.57 (19.12) 10.87 2 8 17 Rice-meal (0.60) (13.44) 2.57 (19.12) (10.87) (2 8) 18 Locust-beans - - 2.14 - - - + -+ + -+ -+ + 19 Malt-combs 2.00 44.80 2.41 5.38 42.39 10 7 20 Fine pollard 2.90 64.96 2.57 3.96 62.39 15 7 21 Coarse pollard 3.50 78.40 2.41 3.07 75.99 19 0 22 Bran 3.60 80.64 2.14 2.65 78.50 19 8 + -+ + -+ -+ + 23 Clover-hay 0.57 12.77 1.38 10.81 11.39 2 10 24 Meadow-hay 0.40 8.96 1.28 14.28 7.68 1 11 + -+ + -+ -+ + 25 Pea-straw 0.35 7.84 1.20 15.31 6.64 1 8 26 Oat-straw 0.24 5.38 1.07 19.89 4.31 1 1 27 Wheat-straw 0.24 5.38 0.92 17.10 4.46 1 1 28 Barley-straw 0.18 4.03 0.84 20.84 3.19 0 9 29 Bean-straw 0.30 6.72 0.88 13.10 5.84 1 5 + -+ + -+ -+ + 30 Potatoes 0.15 3.36 0.32 9.52 3.04 0 9 31 Carrots 0.09 2.02 0.22 10.89 1.80 0 5 32 Parsnips 0.19 4.26 0.26 6.10 4.00 1 0 33 Swedish turnips 0.06 1.34 0.18 13.43 1.16 0 4 34 Mangel-wurzels 0.07 1.57 0.20 12.74 1.37 0 4 35 Yellow turnips (0.06) (1.34) 0.14 (10.78) (1.20) (0 4) 36 White turnips 0.05 1.12 0.13 11.61 0.99 0 3 -+ -+ + -+ + -+ -+ +

- - - - POTASH. - - - Q R S Description No. of Food. Z AA BB CC DD EE FF - - - % lb. lb. % lb. s. d. L s. d. 1 Linseed 1.37 30.69 0.49 1.60 30.20 6 3 2 19 5 2 Linseed-cake 1.40 31.36 0.41 1.31 30.95 6 5 3 18 6 3 Decorticated cotton-cake 2.00 44.80 0.38 0.85 44.42 9 3 5 13 0 4 Palm-nut-cake 0.50 11.20 0.35 3.13 10.85 2 3 1 19 10 5 Undecorticated cotton-cake 2.00 44.80 0.31 0.69 44.49 5 11 3 5 4 6 Cocoa-nut-cake 2.00 44.80 0.31 0.69 44.49 9 3 3 0 7 7 Rape-cake 1.50 33.60 0.25 0.74 33.35 6 11 4 5 4 - 8 Peas 0.96 21.50 0.35 1.63 21.15 4 5 2 15 0 9 Beans 1.30 29.12 0.35 1.20 28.77 6 0 3 3 5 10 Lentils 0.70 15.68 0.35 2.23 15.33 3 2 3 1 4 11 Tares (seed) 0.80 17.92 0.35 1.95 17.57 3 8 3 2 1 - 12 Indian corn 0.37 8.29 0.34 4.10 7.95 1 8 1 5 1 13 Wheat 0.53 11.87 0.34 2.86 11.53 2 5 1 8 7 14 Malt 0.50 11.20 0.35 3.13 10.85 2 3 1 6 8 15 Barley 0.55 12.32 0.34 2.76 11.98 2 6 1 6 1 16 Oats 0.50 11.20 0.33 2.94 10.87 2 3 1 9 10 17 Rice-meal (0.37) (8.29) 0.33 (4.00) (7.96) (1 8) (1 7 10) 18 Locust-beans - - 0.27 - - - - - 19 Malt-combs 2.00 44.80 0.31 0.69 44.49 9 3 3 10 9 20 Fine pollard 1.46 32.70 0.33 1.01 32.37 6 9 2 13 4 21 Coarse pollard 1.50 33.60 0.31 0.92 33.29 6 11 2 17 9 22 Bran 1.45 32.48 0.27 0.83 32.21 6 8 2 18 5 - 23 Clover-hay 1.50 33.60 0.18 0.54 33.42 7 0 2 1 3 24 Meadow-hay 1.60 35.84 0.16 0.45 35.68 7 5 1 8 7 - 25 Pea-straw 1.00 22.40 0.15 0.67 22.25 4 8 0 18 10 26 Oat-straw 1.00 22.40 0.14 0.63 22.26 4 8 0 11 7 27 Wheat-straw 0.80 17.92 0.12 0.67 17.80 3 8 0 10 1 28 Barley-straw 1.00 22.40 0.11 0.49 22.29 4 8 0 10 1 29 Bean-straw 1.00 22.40 0.11 0.49 22.29 4 8 0 17 7 - 30 Potatoes 0.55 12.32 0.04 0.32 12.28 2 7 0 6 5 31 Carrots 0.28 6.27 0.03 0.48 6.24 1 4 0 4 3 32 Parsnips 0.36 8.06 0.03 0.37 8.03 1 8 0 5 5 33 Swedish turnips 0.22 4.93 0.02 0.41 4.91 1 0 0 4 7 34 Mangel-wurzels 0.40 8.90 0.03 0.34 8.93 1 10 0 5 0 35 Yellow turnips (0.22) (4.93) 0.02 (0.34) (4.91) (1 0) (0 3 11) 36 White turnips 0.30 6.72 0.02 0.30 6.70 1 5 0 4 0 - - -



CHAPTER XXVI

THE ROTHAMSTED EXPERIMENTS.

Reference has been so repeatedly made in the preceding pages to the Rothamsted experiments on manures, that it may form a fitting conclusion to the present treatise to give a short account of these famous experiments.

In describing these experiments, the author has remarked elsewhere[256] "that, in respect of their wide scope, dealing as they have done with almost every department of farming, the elaborate care and accuracy with which they have been carried out, the length of time they have been in progress, and, lastly, in respect of the important bearing their results have had on agricultural practice, these famous experiments may be justly described as unrivalled by any other similar ones."

Started on a small scale in 1837 by Sir John (then Mr) Lawes, they were placed on a systematic basis in 1843, in which year Sir John Lawes associated with himself Sir (then Dr) J. Henry Gilbert. They have thus been in progress for a period of fifty years—a fact which was celebrated a few months ago by the presentation of numerous congratulatory addresses from various learned and agricultural societies to the distinguished investigators, and the erection of a memorial granite slab at Rothamsted. What increases the feeling of gratitude due to Sir John Lawes by the agricultural community, is the fact that the entire expense of conducting these experiments has been borne by himself, and he has further most generously handed over to the nation a large sum of money and a certain area of land for carrying them on in perpetuity.

Nature of Experiments on Crops and Manures.

The earliest systematic experiments were on turnips, and since then almost every common crop has been experimented on. Table I. (p. 562) is a list of the different experiments, with their duration, area, and number of plots.

Soil of Rothamsted.

Before describing the more striking results of these experiments, it may be advisable to say that the elevation of the land at Rothamsted is about 400 feet above sea-level; that the average rainfall is about 28 inches per annum; and that the surface-soil is a heavy loam, and the subsoil a stiff clay, resting on chalk.

TABLE I.—LIST OF ROTHAMSTED FIELD EXPERIMENTS.

+ + + Crops. Duration. Area. Plots. + + + Years. Acres. Wheat (various manures) 50 11 34 (or 37) Wheat alternated with fallow 42 1 2 Wheat (varieties) 15 4-8 about 20 Barley (various manures) 42 4-1/4 29 Oats (various manures) 10[1] 0-3/4 6 Beans (various manures) 32[2] 1-1/4 10 Beans (various manures) 27[3] 1 5 Beans, alternated with wheat 28[4] 1 10 Clover (various manures) 29[5] 3 18 Various leguminous plants 16 3 18 Turnips (various manures) 28[6] 8 40 Sugar-beet (various manures) 5 8 41 Mangel-wurzel (various manures) 18 8 41 + + Total root crops 51 + + Potatoes (various manures) 18 2 10 Rotation (various manures) 46 3 12 Permanent grass (various manures) 38 7 22 + + + 1. Including one year fallow.

2. Including one year wheat and five years fallow.

3. Including four years fallow.

4. Including two years fallow.

5. Clover, twelve times sown (first in 1848), eight yielding crops, but four of these very small, one year wheat, five years barley, twelve years fallow.

6. Including barley without manure three years (eleventh, twelfth, and thirteenth seasons).

WHEAT EXPERIMENTS.

The first experiments we shall refer to are those on wheat, since they are among the oldest, and their results the most striking of any.

Unmanured Plots.

Wheat has been continuously grown year after year on three plots for fifty years, without the application of any manure whatever.

We shall first give the results of the first eight years as illustrating the effect of season, which accounts for the irregular results obtained. But for the difference in seasons, we should expect to find a steady decrease in the amount of produce; and this is shown in taking the average of groups of years, as we shall do in the next table.

WHEAT GROWN CONTINUOUSLY ON SAME LAND (unmanured).

TABLE II.—(a.) Remits of first Eight Years (1844 to 1851).

Year. Bushels. Year. Bushels. 1844 15 1849. 19-1/4 1845 23-1/4 1850. 15-7/8 1846 18 1851. 15-7/8 1847 16-7/8 1848 14-3/4 Average of 8 years 17-3/8

TABLE III.—(b.) Results of subsequent Forty Years (1852 to 1891).

Grain Weight per Straw (bushels). bushel. (cwts.) 20 years (1852-1871) 14-1/2 57-5/8 13 20 " (1872-1891) 11-1/2 58-3/4 8-5/8 40 " (1852-1891) 13 58-1/4 10-5/8 49th season (1891) 9-3/8 59-1/2 7-1/2

It is interesting to notice the comparatively slight decrease which has taken place in the yield of wheat during these fifty years. With such wide variations, due to season, it is extremely difficult, as Sir J. Henry Gilbert has pointed out, to estimate rate of decline due to exhaustion. Excluding the very bad seasons, this may be reckoned at from one-fourth to one-third of a bushel per acre per annum. The return of the first year is 15 bushels, while the yield of the forty-ninth season is 9-3/8 bushels. The average of the returns obtained during these fifty years is really in excess of the average yield of the principal wheat-producing countries in the world. This is truly a most astounding result.

The next experiments we shall describe are those on the influence of farmyard manure on the wheat crop when grown continuously.

TABLE IV.—WHEAT GROWN CONTINUOUSLY WITH FARMYARD MANURE (14 tons per annum).

Weight per Bushels. bushel Straw (lb.) (cwts.) 8 years (1844-1852) 28 - - 20 " (1852-1871) 35-7/8 60 33-7/8 20 " (1872-1891) 33-1/2 60-3/8 31-3/8 40 " (1852-1891) 34-7/8 60-1/4 32-5/8

It will be seen from the above results, which contain merely a selection from a very much greater number of experiments, that farmyard manure gives as good an average over the forty years as most of the artificial mixtures do. That this is due to the nitrogen it contains, is strikingly illustrated by the fact that mixed mineral manures alone give less than half the return, and also by the fact that ammonia salts alone give a return twice as great as mineral mixtures; while, lastly, the mixture of mineral manures and ammonia salts gives but a slight increase over that obtained with ammonia salts alone.

The remaining results, selected from a much larger number, need no comment, and we shall give them in tabular form.

Table V.—WHEAT GROWN CONTINUOUSLY WITH ARTIFICIAL MANURES, FARMYARD MANURE, AND UNMANURED.

Average of Forty Years (1852-91).

- PRODUCE PER ACRE AVERAGE PER ANNUM. Dressed grain. MANURES PER ACRE PER ANNUM. Quantity. 20 years, 20 years, 40 years, 1852-71. 1872-91. 1852-91. - bush. bush. bush. Farmyard manure, 14 tons per annum since 1843 35-7/8 33-1/2 34-7/8 Unmanured continuously 14-1/2 11-1/2 13 Mixed mineral manures[1] and 3-1/2 cwt. superphosphate 17 12-7/8 15 Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts 26-1/2 21-3/4 24-1/8 Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts 38-1/4 34-3/4 36-1/2 Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda 36-7/8 34 35-3/8 275 lb. nitrate of soda 26 19-3/8 22-3/4 400 lb. ammonium salts every year since 1845 22-1/2 19 22-1/2 400 lb. ammonium salts, 3-1/2 cwt. superphosphate 28 22-1/4 25-1/8 Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn 31-5/8 29-1/2 30-1/2 - + PRODUCE PER ACRE AVERAGE PER ANNUM. + + Dressed grain. MANURES PER ACRE PER ANNUM. + + Quantity. + + 20 years, 20 years, 40 years 1852-71. 1872-91. 1852-91. -+ + lb. lb. lb. Farmyard manure, 14 tons per annum since 1843 60 60-3/8 60-1/4 Unmanured continuously 57-5/8 58-3/4 58-1/4 Mixed mineral manures and 3-1/2 cwt. superphosphate 58-7/8 59 58-7/8 Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts 59-3/8 60 59-5/8 Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts 59 60 59-1/2 Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda 58-3/8 59-5/8 59 275 lb. nitrate of soda 56-5/8 56-5/8 56-5/8 400 lb. ammonium salts every year since 1845 58 57-3/8 57-5/8 400 lb. ammonium salts, 3-1/2 cwt. superphosphate 57-3/8 58 57-5/8 Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn 59-1/2 60 59-3/4 -+ + -+ PRODUCE PER ACRE AVERAGE PER ANNUM. + MANURES PER ACRE PER ANNUM. Total straw. + 20 years, 20 years, 40 years 1852-71. 1872-91. 1852-91. - cwt. cwt. cwt. Farmyard manure, 14 tons per annum since 1843 33-7/8 31-3/8 32-5/8 Unmanured continuously 13 8-5/8 10-5/8 Mixed mineral manures and 3-1/2 cwt. superphosphate 15 9-3/4 12-3/8 Mixed mineral manures, 3-1/2 cwt. superphosphate, 200 lb. ammonium salts 24-1/2 19-1/8 21-7/8 Mixed mineral manures and 3-1/2 cwt. superphosphate, 600 lb. ammonium salts 41-3/8 39-5/8 40-1/2 Mixed mineral manures, 3-1/2 cwt. superphosphate, 275 lb. nitrate of soda 41-1/2 37-3/4 39-5/8 275 lb. nitrate of soda 28-1/4 18-1/2 23-3/8 400 lb. ammonium salts every year since 1845 24-3/4 16-1/4 20-1/2 400 lb. ammonium salts, 3-1/2 cwt. superphosphate 26-3/8 21 23-3/4 Mineral manure, 3-1/2 cwt. superphosphate, 400 lb. ammonium salts in autumn 31-1/4 28-3/8 29-3/4 - 1. By the term mixed mineral manures is meant a mixture of mineral fertilisers, not including phosphates.

Table VI.—EXPERIMENTS ON THE GROWTH OF BARLEY FOR FORTY YEARS, 1852-91.

- PRODUCE PER ACRE AVERAGE PER ANNUM. Dressed grain. MANURES PER ACRE PER ANNUM. Quantity. 20 years, 20 years, 40 years, 1852-71. 1872-91. 1852-91. - bush. bush. bush. Unmanured continuously 20 13-1/4 16-1/2 3-1/2 cwt. superphosphate of lime 25-1/2 17-3/4 21-3/4 Mixed mineral manures 22-1/2 13-1/2 18 Mixed mineral manures, 3-1/2 cwt. superphosphate 27-1/2 17-1/4 22-3/8 200 lb. ammonium salts 32-1/2 25-5/8 29 200 lb. ammonium salts, 3-1/2 cwt. superphosphate 47 38-1/2 42-3/4 200 lb. ammonium salts, mixed mineral manures 35 27-3/4 31-3/8 Manures, 3-1/2 cwt. superphosphate of lime 46-1/4 40-3/4 43-1/2 275 lb. nitrate of soda 37 28-3/8 32-3/4 275 lb. nitrate of soda, 3-1/2 cwt. superphosphate 49-1/4 42-1/4 45-3/4 275 lb. nitrate of soda, mixed mineral manures. 37-3/8 29-1/2 33-1/2 275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate 49-3/4 41-1/4 45-1/2 1000 lb. rape-cake 45-1/4 37-1/8 41-1/4 1000 lb. rape-cake, 3-1/2 cwt. superphosphate 46-3/4 40 43-3/8 1000 lb. rape-cake, mixed mineral manures 43-5/8 35-5/8 39-1/2 1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate 47-3/8 39 43-1/4 Farmyard manure, 14 tons every year 48-1/4 49 48-5/8 -

+ PRODUCE PER ACRE AVERAGE PER ANNUM. + + Dressed grain. MANURES PER ACRE PER ANNUM. + + Quantity. + + + + 20 years, 20 years, 40 years 1852-71. 1872-91. 1852-91. -+ + + + lb. lb. lb. Unmanured continuously 52-3/8 51-3/4 52 3-1/2 cwt. superphosphate of lime 53-1/4 53 53-1/8 Mixed mineral manures 53 51-7/8 52-1/2 Mixed mineral manures, 3-1/2 cwt. superphosphate 53-3/8 52-3/8 53 200 lb. ammonium salts 52-1/8 52 52 200 lb. ammonium salts, 3-1/2 cwt. superphosphate 53-3/8 52-1/4 52-7/8 200 lb. ammonium salts, mixed mineral manures 52-3/4 52-1/2 52-5/8 Manures, 3-1/2 cwt. superphosphate of lime 54 54-1/8 54 275 lb. nitrate of soda 52 52-1/8 52 275 lb. nitrate of soda, 3-1/2 cwt. superphosphate 53-3/8 53-1/4 53-1/4 275 lb. nitrate of soda, mixed mineral manures. 52-1/4 52-3/4 52-1/2 275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate 53-3/8 54 53-5/8 1000 lb. rape-cake 53-3/4 53-7/8 53-7/8 1000 lb. rape-cake, 3-1/2 cwt. superphosphate 53-7/8 54-3/8 54-1/8 1000 lb. rape-cake, mixed mineral manures 53-3/4 54-1/8 54 1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate 53-5/8 54-1/4 53-7/8 Farmyard manure, 14 tons every year 54-3/8 54-1/4 54-1/4 -+ + + +

-+ PRODUCE PER ACRE AVERAGE PER ANNUM. + MANURES PER ACRE PER ANNUM. Total straw. + 20 years, 20 years, 40 years 1852-71. 1872-91. 1852-91. -+ + + cwt. cwt. cwt. Unmanured continuously 11-3/4 6-7/8 9-3/8 3-1/2 cwt. superphosphate of lime 13-3/8 8-1/4 10-3/4 Mixed mineral manures 12-1/4 7 9-5/8 Mixed mineral manures, 3-1/2 cwt. superphosphate 14-3/8 8-3/8 11-3/8 200 lb. ammonium salts 18-1/2 13-1/2 16 200 lb. ammonium salts, 3-1/2 cwt. superphosphate 27-5/8 20-1/8 23-7/8 200 lb. ammonium salts, mixed mineral manures 20-1/4 15-1/8 18 Manures, 3-1/2 cwt. superphosphate of lime 28-1/2 23-3/8 25-7/8 275 lb. nitrate of soda 22-1/8 15-7/8 19 275 lb. nitrate of soda, 3-1/2 cwt. superphosphate 30-1/2 23-3/8 27 275 lb. nitrate of soda, mixed mineral manures. 23-7/8 17-1/2 20-3/4 275 lb. nitrate of soda, mixed mineral manures, 3-1/2 cwt. superphosphate 32-3/8 24-1/2 28-1/2 1000 lb. rape-cake 26-7/8 20 23-3/8 1000 lb. rape-cake, 3-1/2 cwt. superphosphate 28-3/8 21-1/2 24-7/8 1000 lb. rape-cake, mixed mineral manures 27-1/8 19-7/8 23-1/2 1000 lb. rape-cake, mixed mineral manures, and 3-1/2 cwt. superphosphate 29-3/4 21-7/8 25-5/8 Farmyard manure, 14 tons every year 28-1/4 29-3/4 29 -+ + +

TABLE VII.

EXPERIMENTS ON THE GROWTH OF OATS, 1869-78.

-+ AVERAGE PER ANNUM. 5 YEARS, 1869-73. + MANURES PER ACRE PER ANNUM. Dressed grain. + + + Total Quantity. Weight straw. per bushel. -+ + + Bushels. lb. cwt. Unmanured 19-7/8 33-3/4 10-3/8 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate of lime 24-1/2 35 13-3/8 400 lb. ammonium salts 47 35-7/8 28-1/2 400 lb. ammonium salts, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate 59 37 41-1/8 550 lb. nitrate of soda 47-1/8 35-1/2 27-1/2 550 lb. nitrate of soda, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate 57-1/2 35-3/4 35 -+ + + AVERAGE PER ANNUM. 4 YEARS, 1874-78. -+ Bushels. lb. cwt. Unmanured 13-3/4 31-1/4 6 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate of lime 13-1/8 31-5/8 6-1/8 200 lb. ammonium salts. 28-7/8 33-1/4 14-1/8 200 lb. ammonium salts, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate 38 35-1/2 20 275 lb. nitrate of soda 26-3/8 31-5/8 11-1/8 275 lb. nitrate of soda, 200 lb. sulphate potash, 100 lb. sulphate soda, 100 lb. sulphate magnesia, and 3-1/2 cwt. superphosphate 28-1/2 34-1/8 14 -+ + +

TABLE VIII. EXPERIMENTS ON ROOT CROPS: SWEDISH TURNIPS. Fifteen Seasons, 1856-70.[1] Roots and Leaves carted off the Land. - -+ SERIES 1. Standard manures only. PLOT. STANDARD MANURES. -+ - Roots. Leaves. Tons. cwt. Tons. cwt. 1 Farmyard manure, 14 tons 6 4 0 17 2 Farmyard manure, 14 tons, and superphosphate 6 7 0 16 3 Without manure, 1846, and since 0 11 0 3 4 Superphosphate, each year; sulphate potash, soda, and magnesia, 1856-60 2 16 0 8 5 Superphosphate, each year 2 12 0 9 6 Superphosphate, each year; sulphate potash, 1856-60 2 7 0 7 7 Superphosphate, each year; sulphate, potash, and 36-1/2 lb. ammonium salts, 1856-60 2 12 0 7 8 Unmanured 1853, and since; previously part unmanured; part superphosphate 1 3 0 4 -

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