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ON POTATO FAILURES.

The Potato Rescued from Disease and Restored to Pristine Vigour, by a plan of Keeping and Cultivation founded on the Natural Principles of the Vegetable Economy. By WILLIAM AITKEN, Castle Douglas. Blackwood & Sons, Edinburgh: T. Cadell, London. 1837.

The Failure of the Potato Crop ascertained and demonstrated from Analogy ; with a Remedy and Test for the Present Seed to prevent Failures. By a DUMBARTONSHIRE FARMER. John M'Leod, Glasgow.

1837.

It is too late in the period of its history to expatiate on the importance of the potato.. Suffice it to be known that it is an essential ingredient in the national food. Any circumstance, therefore, which might detract from the prolificacy of its reproduction, commands serious consideration, and should excite national alarm. Grounds for such alarm have manifested themselves, and their investigation, philosophically and practically, demands the combined efforts of the man of science and the farmer. We are not aware that the cause of the potato failure has hitherto been investigated by scientific men, but the extensiveness of those failures, of late years, pressing hard on the interests of the cultivator, has impelled him into the investigation, with the urgency of necessity. The maxim felix qui potuit rerum cognoscere causas, is true, whether the investigator of causes be a man of science or a man of practice; but the latter too easily rests satisfied with the degree of happiness derivable from the discovery of only secondary causes; and they are they which are most obviously connected with his daily operations. The explanations of potato failures hitherto tendered by practical men, have, therefore, been based on the results of secondary causes. The numerous authors of the various papers which have been transmitted to the Highland Society on the subject, have merely criticised various portions of subsidiary practice, which, under the altered condition of the potato, no doubt require amendment, and thus contenting themselves, have not extended their observations to the source of the evil. It is worth while to trace their workings within the boundary of secondary causes, beyond which few have thought it necessary to pass; and a few instances of expressed opinion will perhaps sufficiently illustrate the limited observation which they have taken.

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One writer, for example, affirms, that the potato failure arises from the seed having been heated by being kept in too great quantities in pits or houses; but large quantities of potatoes have been kept in pits or houses, and to a great depth, tco, long before the appearance of the potato failure. And yet the fact may be, that potatoes are now heated in pits and houses, and will not in consequence grow. But what was that which enabled the potato to escape failure until lately, even when kept in depth in pits or houses? Another asserts, that cut sets become heated in large heaps, and will not, in consequence, grow. It is very possible that cut sets become heated, while lying for a time in large heaps on the barn floor. But who has not seen, until lately, large heaps of cut sets waiting with impunity for weeks until they were planted? What was that which enabled the cut sets escape failure then and be overtaken with it now? A third ascribes the failure to the manure being in a fresh state when brought in contact with cut sets. We have frequently seen old straw-ropes laid along the drill raise excellent crops of potatoes; and who has not seen horse-dung taken out fresh from the court, and applied to potato-land without incurring, until lately, a risk of failure? It may be, that fresh dung now destroys the vitality of the potato set, but what was that which prompted the cultivator then to disregard the state of the manure when applied to potato-culture? Another writer is certain, that dry weather in the time of planting, and a continuance of it after, wards, destroys the vitality of the sets and causes the failure; and thus he blames the dry weather of the last three years for the failure. But who, that has lived some time in the world, has not seen many dry springs before those of the last few years, and long before the potato-failure was known? There have been few years which can be compared for drought with 1826, and yet no cultivator experienced potato failure that year. We had then the misfortune to farm gravelly soil, and could the combined agencies of heat and dry soil cause failure, our potatoes could not possibly have escaped it; for when they were setting, the ground felt as if scorched with fire through thick soled shoes, and the dung was, almost dried to a potsherd before it could be got covered in with the utmost expedition, by people and horse, and yet no failure occurred, nor was any appre-,

hended. But it may be that heat now destroys the vitality of potato sets, and yet what was that which enabled the sets to escape with life in 1826, and yet perish by the milder droughts of the last three years? To avoid failure, many recommend sets to consist of whole potatoes, or, if cut, to be placed on the dung on the skinny side, or to be planted during the cooler part of the day, in the morning and evening. These precautions may now, no doubt, be very proper and necessary, but why were they not necessary years ago? What is that which enabled the cultivator formerly to disregard these precautions? Some conceive that the land having been too much cropped with the potato, has become sick of its growth, as in the case of red clover. Whatever force this observation may have had some years ago, when the land was constantly stirred and cropped, it cannot so forcibly apply to the last three years, because the rotations now permit a longer term to grass, and land, in general, is treated with greater leniency and manured more liberally than ever? What is that which enabled the potato to defy failure when the land was constantly over-cropped and under-manured?

As long as such diversity of opinion exists on the cause of the potato failure, it is obvious there can be no community of purpose among the holders of these opinions, who are also the cultivators of the potato, to discover its probable cause; for the prevalent belief that one effect, that is, the same failure can be produced by so many, and some of them opposite, causes, as we have enumerated, must be founded on improbability, and not on the laws which regulate other natural phenomena. Guided by his peculiar belief, each cultivator may, no doubt, so contrive to manage his potato culture, as to avoid for a time the most aggravated failure; but he cannot assure himself of safety for even one season, far less can he depend on the infallibility of his management for a series of years. Whichever of those peculiar opinions he may have adopted, he will most probably be obliged to relinquish it, and adopt those of other cultivators, perhaps the very one which he had formerly ridiculed. In adopting this change he may nevertheless feel satisfaction, that he is obeying the dictates of experience, though not of his own. But the time will at length arrive when he will be wearied pursuing so many desultory practices, even although they should all have

been sanctioned by experience. In his perplexity he will probably be tempted to ask himself, what is that which makes so many methods, hitherto acknowledged excellent, of raising potatoes, all terminate now in failure? Were the question repeatedly asked by cultivators, whether at themselves or others, a hope might be cherished that the spirit of investigation was about to dwell in their bosoms, and the result might be anticipated that the light of philosophy was about to illumine the operations of the field.

But some cultivators have already been asking themselves the question proposed; and the response which they have received consists of conjecture, whose probable accuracy derives confirmation from daily experience. The conjecture has the merit of explaining all the phenomena of failure, and reconciling their discrepancies. It can appeal to analogy for the correctness of its principle, and, admitting that its application to potato culture may, in time, be proved to be untenable, the practice founded on it, in the mean time, can entail no loss or inconvenience to the cultivator. The conjecture is, that the potato, as a plant, has lost its constitutional vigour. We give this principle of the failure at present no higher pretensions than of being founded on conjecture, but if it, like many theories which have sprung from conjecture, be confirmed by subsequent experiment, it will deserve to be invested with all the authority of sound theory. Now, let us apply this conjectural principle to the various phenomena exhibited by the failure, and thereby ascertain whether they are explicable by the theory of constitutional decay: For example, are potatoes now heated when stored in depth, in pits and houses, more readily than formerly? it is, because being constitutionally weaker, they are less able to endure the rough treatment of former times. Are cut sets now easily heated when lying in heaps? the same reason will explain the circumstance. Does dry manure now effect potato failure? it is because the weakened sets are unable to resist, to them, the mortal effects of active fermentation in the manure, until the manure has incorporated itself with the soil? Does a scorching drought now produce potato failure? it is because the intensity of the heat actually deprives the sets of vitality, in their present debilitated condition. In short, take the sets under every circumstance of fail

ure, let them fail when planted at mid-day, and grow when planted in the morning and evening; let them fail when the cut side is presented to the dung, and grow when the skinny side is so placed; let them fail when cut, and grow when planted whole, when the skin, as in the last instance, acts as a protection to the pulp; let them fail when planted in dry soil, and succeed when planted in damp, where their natural sap is retained, the same principle of constitutional weakness will explain every one of these phenomena, for every instance of failure occurs in situations more likely to be fatal to the vitality of the sets than in situations in which the crop succeeds. No doubt, each of the multitude of secondary causes, such as heating of the seed, heat of the sun, dryness of the manure, and many others, will also explain one or more of the phenomena of failure; but the confidence of the cultivator will be shaken in them all, when he discovers, in his endeavours to avoid one cause, by a particular change of culture, he may suffer from the effects of another, for all his precautions, suggested by these numerous causes, may not insure him against disappointment. Although armed with every precaution, he plants his crop in dread. He may conceive he may, but he can only with a trembling heart, pray Heaven to be gracious, for he thinks he has done his part; but, in fact, for all he imagines he has accomplished, he has not nearly done his part, nor done that part well. He has confined his observation to the facts which surround him. Like the child who is afraid of the burning embers which have set fire to its clothes, is yet heedless of the danger from the fire itself. Would it not be more philosophical, more like a desire for truth, to extend observation beyond the narrow hounds of daily practice, for explanation of a phenomenon, which assumes, like Proteus, 30 many shapes within our view? Would it not be more philosophical, more conformable to Nature's laws, to believe that a single principle which evidently effects mutation in living objects, both in the animal and vegetable economy, should account for rather than a plurality of causes, the variations of a mutable phenomenon? This principle is constitutional weakness in the potato, superinduced by a peculiarity of treatment.

But granting that vegetables do decay in constitution by peculiar treatment, how, it may be asked, is it known, or can be