As the cultivation of sugar-beet, and its manufacture into sugar, has been occupying of late a considerable amount of attention in New Zealand, the following information, gained principally from some practical acquaintance with the subject, may not be uninteresting at the present time:—
There are in cultivation four kinds of beet, viz.:
1. The long red, or garden-beet, so much used as a salad.
2. The white Silesian, or sugar-beet, with its sub-variety, the rose-coloured.
3. The sea-beet, the leaves of which are well known as an excellent substitute for spinach.
4. The mangold-wurzel, or field-beet. Von Thäer, a German writer on agriculture, is of opinion that the field-beet is a hybrid betwixt the red garden-beet and the white sugar-beet. Others say that it is the original stock, and that the finer varieties have been produced from it by higher cultivation—a more likely conjecture.
Of the white sugar-beet (Beta alba) there are more than one species. It has a pear-shaped root and light green top, green leaves with lighter-coloured
ribs and white flesh. There is a variety of it which has a rose-coloured skin, leaves marked by purple-coloured ribs, but the flesh is white like that of the former. There is no difference in their sugar-yielding qualities.
The average temperature of the continental beet-growing countries, and of the localities in England where beets are grown to advantage, ranges from 62° to 65° Fahr.
The average composition of the root of the sugar-beet of France, Belgium, and the Rhenish provinces, is theoretically nearly as follows:—
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|Sugar||10½ per cent.|
Practically the per centage of sugar extracted reaches about 8 per cent. But the proportion varies very much. Thus it is greater:—
1. In small beets than in large. Chemical inquiry has proved that the proportion of sugar was larger, and of salt less, in beets not weighing more than three pounds. One per cent. of salt in the sap will render three per cent. of the sugar uncrystallizable. The best roots weigh on an average from one and a half to two and a half pounds each.
2. In dry climates, and especially when the climate is dry after the roots have begun to swell.
3. When grown in light potato or barley soils than in heavy soils. The land should be well drained and capable of being cultivated to a depth of eighteen inches.
4. In the part under than above ground. The tap root is the richest in sugar.
5. When manure has not been directly applied to the crop, as its contact with the plants occasions unequal growth, as well as infests them with various kinds of insects. Strictly speaking the manure should be worked into the ground some months previously to the seed being sown. Superphosphate of lime and bone-dust are the best manures for this root.
It has been proved that a crop raised by means of the direct application of manure contains more salt, and gives more uncrystallizable syrup, than when raised without direct manuring. At the factory where this was tested a larger price, therefore, was offered for roots grown upon land which had been manured during the previous winter; a higher still for such as were raised after a manured crop of corn; and a still higher when after the manuring two crops of corn were taken before the beet was sown.
In France and Belgium the crops gathered are from fourteen to fifteen
tons an acre, while about Magdeburg, in Prussian Saxony, they do not exceed ten or twelve tons. But the latter are richer in sugar and poorer in salts in proportion.
These facts show how much practical agriculture, as well as climate, have to do with the success of this important manufacture.
Having regard, therefore, to the use and application of suitable manures, and the proper rotation of crops, the mechanical cultivation of the sugar-beet should be pursued as follows:—
The ground is to be prepared for it in the same manner as for mangold-wurzel, turnips, or carrots. The best seed is to be got from Magdeburg, in Prussia, or from M. Vilmorin, the celebrated seedsman in Paris. It should be sown in this country in October. Ten pounds to twelve pounds of seed is the quantity required per English acre. Sugar-beets are planted more closely than mangolds. The distance between the rows, and from plant to plant, should not be less than twelve inches nor greater than eighteen inches. If the young plants are caught in spring by a night's frost they should be ploughed up and fresh seed sown. They should be horse and hand-hoed. The earth should be well gathered up round each plant, in order that the head of each root may be completely covered with soil. When the roots begin to show the commencement of decay in the leaves, they are ripe, and should be dug out, the mould gently shaken off, and the heads cut off together with as much of the roots as shows the presence of leaf-buds. They should then be piled in heaps on the ground to hinder the evaporation of their moisture, and covered with a layer of earth to protect them from light and frost. A beet-root of good quality should not exceed three pounds in weight, and should be firm, brittle, emitting a creaking noise not unlike a pine-apple when cut, and perfectly sound within; the degree of sweetness is also a good indication.
It will be seen by these directions what conditions are necessary to ensure a good root for sugar purposes. Until, however, the experiment which is now being tried of cultivating it in the neighbourhood of Nelson has been tested by chemical analysis, it would be premature to enter into the details of its further treatment in reference to its manufacture into sugar; if the result is satisfactory, there will be read to you at a future time a continuation of this paper, dealing with the several aspects of the question in a manufacturing point of view.
An interesting discussion ensued on the nature of the different kinds of sugar-beet, as well as on their cultivation and manufacture into sugar at a profit in New Zealand, and a vote of thanks was accorded to Mr. Mackay, for his useful and practical paper.