Let, however, our grand birds of prey be encouraged, instead of being shot by the keeper as vermin, or knocked over by the prowling bird-stuffer, in order to be perched up in a box for sale to some Cockney, who would fain be considered as fond of sport because his “den,” perchance, contains a stuffed owl, hawk, magpie, or some other specimen.
On a recent visit to Dorsetshire, on our own farm, we saw a man employed to “keep the birds” from a field where several labourers were engaged barley sowing; and it is quite true that, unless he had been there, the rooks would have as industriously followed the drill as they do the plough; but, as we thought, scarcely to pick up barley in the breeding season, when there was metal more attractive in the recently-hatched Elater obscurus, parent of the wireworm, which were thicker than we ever saw them before, and, doubtless, the disturbance of the soil brought these and two or three generations of wireworms to the surface. Now, we do not hesitate to give as our opinion that this birdkeeper would have done more good to the barley and the succeeding clover crop by picking up a hundred or two of these beetles and destroying them than by blazing away at rooks for a twelvemonth, and this certainly might have been done in an hour or two.
Still, that some soils do get incapable of growing a clover crop is pretty certain; and it may, we think, be equally settled that this does not entirely depend upon their having been exhausted of the ingredients which analysis demonstrates clover to contain, for we certainly have seen clover succeed after the burning of so-called clover-sick land; and though there is reason to think that this result was partially due to the setting free of a fresh supply of manurial ingredients, we are still convinced that the burning out of humus or peaty vegetable matter and the destruction of insects had their share in the induced change.
Still, however much we may suppose that the failure of the clover crop is influenced by the alteration of its constitution as the result of cultivation, the presence of choking weeds, or by the presence of prejudicial ingredients, especially in thin soils, there can be no doubt that the principal cause of the difficulty will be found in the fact that the corn crop with which the clover is grown exhausts the soil, in the most unsparing manner, of the very chemical ingredients which the clover requires.
Thus, if sheep are folded on a crop of turnips, the whole of this crop is converted into a manure at once available for the grain crop, by which it is quickly appropriated and then taken away. Here, then, we may suppose at starting that the clover is half starved; and, with a constitution drawn up in the effort of the plants to obtain a glance of sunshine, and weakened for the want of nourishment, it is expected to bear our inclement winters.
This argument will be made all the clearer if we place side by side the result of the analyses of barley and clovers, and especially if we consider what a quantity of mineral matter is taken in a short time, and by a crop ripening its straw and seed.
Now, if we look at these figures we shall see how much of the mineral matter required for the clover has been previously abstracted by the barley, and if at the same time we reflect that this robbery may, and too often does, co-exist with the other causes which we have instanced as tending to clover-sickness, we should no more call land sick of clover because it will not bear this crop under our exhaustive system of cultivation than we should call a barren sand wheat-sick for refusing to grow corn.
| ANALYSES OF BARLEY AND CLOVER. | ||||||
| PLAYFAIR | WAY. | |||||
| Barley Grain. | Barley Straw. | Red Clover. | White Clover. | |||
| Silica | 28·97 | 46·30 | 3·34 | 3·68 | ||
| Phosphoric acid | 35·68 | 3·22 | 6·35 | 11·53 | ||
| Sulphuric acid | 1·22 | 2·61 | 4·18 | 7·21 | ||
| Carbonic acid | 16·93 | 18·03 | ||||
| Lime | 3·06 | 7·59 | 35·39 | 26·41 | ||
| Magnesia | 8·04 | 3·55 | 11·22 | 8·15 | ||
| and loss | and loss | |||||
| Peroxide of iron | 1·94 | ? | 4·35 | ? | 0·97 | 1·96 |
| Potash | 15·61 | 22·17 | 14·85 | 14·33 | ||
| Soda | 5·03 | 0·84 | 1·40 | 3·72 | ||
| Chloride of sodium | 0·45 | 9·37 | 2·36 | 4·94 | ||
| Chloride of potassium | 2·96 | |||||
| 100·00 | 100·00 | 99·95 | 99·96 | |||
We cannot better conclude this chapter than by quoting the following from Baron Liebig’s Letters on Modern Agriculture, so ably translated by Professor Blyth:—
The simplest peasant has sense enough to see, and all agriculturists agree with him, that clover, turnips, hay, &c., cannot be sold off from a farm without most materially damaging the cultivation of the corn. Every one willingly admits that the sale and exportation of clover, turnips, &c., exercise a detrimental influence on the growing of corn. “Above all, let us take care to have plenty of fodder; the corn crop[146] will then take care of itself.” But that the exportation of corn may possibly exercise an injurious influence on the cultivation of clover or turnips; that it is, above all, indispensable to restore to the soil the mineral constituents of the corn, to enable the clover or turnip crop to “take care of itself;” in other words, that in order to grow clover, turnip, &c., we must manure the land—this is a notion utterly incomprehensible, nay absolutely impossible, for most agriculturists. For, is not the clover grown for the sake of manure? What advantage, then, would there be if it were necessary to manure again to produce the clover? This clover the farmer expects to grow for nothing.
The mutual relations existing in the order of nature between the two classes of plants are, however, as clear as daylight. The mineral constituents of the clover, turnips, &c., and of the corn, form the conditions for the production of the clover, turnips, &c., and of the corn, and they are in their elements quite identical. The clovers, &c., require for their growth a certain amount of phosphoric acid, potash, lime, magnesia,—so does the corn. The mineral constituents contained in the clover are the same as those in the corn, plus a certain excess of potash, lime, and sulphuric acid. The clover draws these constituents from the soil; the cereal plant receives them,—we may so represent it from the clover. In selling his clover, therefore, the farmer removes from his land the conditions for the production of corn. If, on the other hand, he sells his corn, there will be no clover crop in the following year; for in his corn he has sold some of the most essential conditions for the production of a clover crop.—pp. 183-5.