| ANALYSES OF TURNIPS. | |||||
| Swedish Turnip. | White Globe. | Aberdeen Yellows. | Purpletop Yellows. | Norfolk Bell. | |
|---|---|---|---|---|---|
| Water | 89·460 | 90·430 | 90·578 | 91·200 | 92·280 |
| Albuminous, or flesh-forming substances | 1·443 | 1·143 | 1·802 | 1·117 | 1·737 |
| Non-nitrogenous, or fat-forming substances (fat, gum, sugar, &c.) | 5·932 | 5·457 | 4·622 | 4·436 | 2·962 |
| Woody fibre | 2·542 | 2·342 | 2·349 | 2·607 | 2·000 |
| Mineral matter (ash) | 0·623 | 0·628 | 0·649 | 0·640 | 1·021 |
| 100·000 | 100·000 | 100·000 | 100·000 | 100·000 | |
The Greystone Turnip is a variety which has only quite recently been introduced. It is stated to be an uncommonly productive crop, usually yielding returns from 30 to 50 per cent. greater than those obtained from other varieties of the turnip. The composition of the Greystone turnip appears to be inferior, so that probably it is not, after all, a more economical plant than the ordinary kinds of turnips.
| DR. ANDERSON'S ANALYSIS OF THE GREYSTONE TURNIP. | ||
| No. 1. Grown on Clay. | No. 2. Grown on Sand. | |
|---|---|---|
| Water | 93·84 | 94·12 |
| Oil | 0·26 | 0·34 |
| Soluble albuminous matters | 0·35 | 0·56 |
| Insoluble ditto | 0·20 | 0·18 |
| Soluble respiratory matters | 2·99 | 2·32 |
| Insoluble ditto (chiefly fibre) | 1·73 | 1·85 |
| Ash | 0·63 | 0·63 |
| ——— | ——— | |
| 100·00 | 100·00 | |
It was at one time the fashion—not yet become quite obsolete—to regard the proportion of nitrogen in the turnip as the measure of the nutritive value of the bulb; but the fallacy of this opinion has been shown by several late investigators, and more particularly by the results of one of the numerous series of feeding experiments conducted by Mr. Lawes. Many bulbs exceedingly rich in nitrogen are very deficient in nutritive power—partly from a deficiency in the other elements of nutrition—partly because most of their nitrogen is in so low a degree of elaboration as to be incapable of assimilation by animals. The value of a food-substance does not merely depend upon the amount and the relative proportion of its constituents, but also, and to a very great extent, upon their easy assimilability. There is but little doubt that the nutritive matters contained in the Swedish turnip when the bulb is fresh are very crude. By storing, certain chemical changes take place in the bulb, which render it more nutritious and palatable. A large proportion of the non-nitrogenous matters exist in the fresh root as pectin; but this substance, if the bulb be preserved for a couple of months, becomes in great part converted into sugar, which is one of the most palatable and fattening ingredients of cattle-food. By storing, too, the bulbs lose a portion of their excessive amount of water, and become less bulky, which is unquestionably a desideratum. These facts suggest the necessity for cultivating the earlier varieties of the turnip, for it may be fairly doubted if a late-grown crop, left for consumption in the field, ever, even under the most favorable circumstances, attains its perfect development. At the same time it must not be forgotten that turnips fully matured in the field rather deteriorate than otherwise after a few weeks' storage.
Many agriculturists consider that there is a strict relation between the specific gravity, or comparative weight of the bulb, and its nutritive value; others believe that a very large turnip must necessarily be inferior in feeding qualities to a small one; whilst not a few maintain that neither its size nor its specific gravity is an indication of its feeding qualities. Dr. Anderson, who has specially investigated a portion of this subject, states that "the specific gravity of the whole turnip cannot be accepted as indicating its real nutritive value, the proportion of air in the cells being the determining element in such results; that there is no constant relation between the specific gravity of, and the nitrogen compounds in, the bulb; and that such relation does exist between the specific gravity of the expressed juice and the nitrogen compounds and solid constituents." Dr. Anderson allows, however, that the best varieties of the turnip have the highest specific gravity; which admission—coupled with the fact admitted by all experimenters that the heavy roots store best—lead me to adopt the opinions of those who consider great specific gravity as one of the favorable indications of its nutritive value. With respect to size, I prefer bulbs of moderate dimensions; the monsters that win the prizes at our agricultural shows—and which, in general, are forced—are inferior in feeding qualities, are always spongy, and almost invariably rot when stored.
The composition of the turnip is influenced not only by the nature of the soil on which it is grown, but also by that of the manure applied to it. The most reliable authorities are agreed that turnips raised on Peruvian guano are watery, and do not keep well; but that with a mixture of Peruvian guano and superphosphate of lime, with phospho-guano, or with farmyard manure supplemented with a moderate amount of guano, the most nutritious and firm bulbs are produced.
Turnip-tops have been analysed by Voelcker, with the following results:—
| ONE HUNDRED PARTS CONTAIN— | ||
| White. | Swedish. | |
|---|---|---|
| Water | 91·284 | 88·367 |
| Nitrogen compounds | 2·456 | 2·087 |
| Non-nitrogenous matters (gum, sugar, &c.) | 0·648 | 1·612 |
| Ditto, as woody fibre | 4·092 | 5·638 |
| Mineral matter | 1·520 | 2·296 |
| ——— | ——— | |
| 100·000 | 100·000 | |