These figures apparently show that the tops of turnips are more valuable than their bulbs; but, in the absence of any feeding experiments made to determine the point, we believe they are less so, as a very large proportion of the solid matter in the tops of turnips is in too low a degree of elaboration to be assimilable. Their high proportions of nitrogen and mineral matter constitute them, however, a very useful manure—nearly twice as valuable as the bulbs; this fact should be borne in mind when turnips are sold off the land.
The Mangel-wurtzel is one of the most valuable of our green crops. Its root is more nutritious than the turnip, occupying a position in the scale of food equivalents midway between that bulb and the parsnip. Mangels, when fresh, possess a somewhat acrid taste, and act as a laxative when given to stock; but after a few months' storing they become sweet and palatable, and their scouring property completely disappears.
Although the mangel is one of the most nutritious articles of food which can be given to cattle, yet it is stated on the best authority that sheep do not thrive upon it. Voelcker, who has investigated this subject, informs us that a lot of sheep which he fed on a limited quantity of hay and an unlimited quantity of mangels, did not, during a period of four months, increase in weight, whilst another lot of sheep supplied with a small quantity of hay, and Swedish turnips ad libitum increased on an average 2½ lbs. weekly. I believe the experience of the greater number of feeders agrees with the results of Dr. Voelcker's experiment.
The chemistry of the mangel-wurtzel has been thoroughly studied by Way and Ogston, Fromberg, Wolff, Anderson, and Voelcker. According to the last-named chemist, its average composition is as follows:—
| Water | 87·78 |
| Flesh-forming matters | 1·54 |
| Sugar | 6·10 |
| Gum, pectin, &c. | 2·50 |
| Woody fibre | 1·12 |
| Mineral matter (ash) | 0·96 |
| ——— | |
| 100·00 |
It is difficult to accurately determine by a comparative trial the relative feeding properties of mangels and turnips, for the former are only in a fit state to be given to the animals when the latter are deteriorating. However, by comparing the composition of the two substances, and the results obtained from numerous feeding experiments, it would appear, that on the average 75 lbs. weight of mangels are equal to 100 lbs. weight of turnips. Of the different varieties of the mangel the long yellow appears to be the most nutritious, and the long red the least so.
The leaves of the mangel—some of which are occasionally pulled and used for feeding purposes, during the growth of the bulb—are an excellent feeding substance: their composition indicates a nutritive value but little inferior to that of the root; but as their constituents cannot be in a highly elaborated condition, it is probable they are not more than equal to half their weight of the bulbs.
One questio vexata of the many which at present occupy the attention of the agricultural world is, whether or not the leaves of mangels may be removed with advantage during the latter part of the development of the plants. This practice prevailed rather extensively a few years since, but latterly it has fallen somewhat into disuse.
Those who adopt this plan urge, as its advantages, that a large quantity of food is obtained at a time when it is urgently needed, and that instead of the removal of the leaves exercising an injurious influence on the development of the roots, the latter are actually increased in size.
In 1859 an experimental investigation was carried out at the Glasnevin Model Farm, with the view of throwing new light on the question. The outside leaves were very gradually removed on different occasions—from the 12th August to the 15th October. In this way five tons of leaves per statute acre were removed, and subsequently made use of for feeding purposes. The experiment was conducted on a field of four acres, of which the produce of 12 drills, each 200 yards in length, was left untouched. The result was that the produce of the roots of the untouched plants was only 40 tons 8 cwt. 6 qrs. per acre, whilst the roots of the plants which had been partly denuded of their leaves weighed at the rate of 45 tons 1 cwt. This experiment afforded results which are apparently favorable to the practice of stripping the leaves; but it is to be regretted that it was not rendered more complete by an analysis of the roots, as a great bulk of roots does not necessarily imply a great weight of dry food, and it is just possible, though not very probable, that the roots of the stripped mangels contained a larger proportion of water than those of the untouched plants.