the non-proteid nitrogen increased, especially during the second period, January to March.

CONCLUSIONS.

(1) Apart from the loss of nitrates which takes place during the first two months of storage, it is difficult, in view of the small amount of crude fibre and the still smaller amount of indigestible proteids which mangels contain, to see in what way the roots can undergo any material improvement when stored.

(2) On the other hand it is evident that the roots may, and probably do, lose a very appreciable amount of their most important constituent, sugar. As far as the experiments go there is no evidence of any actual increase of digestible proteids, whilst a loss is shown to be at any rate possible. Loss of furfuroids seems to be as general as the loss of sugar.

(3) The convenience of having mangels for feeding up to the early summer months probably compensates for the losses which may be assumed to occur under ordinary conditions. But there seem to be good reasons for doubting the advisability of prolonging the storage, especially when the extra trouble involved in order to prevent rotting is taken into account.

To the results of the experiments above recorded may be appended a further statement on the composition of a single mangel kept in clamp for a year. Owing to the loss by decay of many of the roots stored in 1898, it was decided to reserve a much greater number of roots from one plot only. Accordingly, in November, 1899, 100 roots were selected from the produce of Plot 2 O, Barnfield. After twisting off the tops the roots were cleaned, weighed, provided with zinc labels, and clamped in the usual manner, the only difference being in the size of the heap. On opening the clamp in November, 1900, very few of the roots were recognisable as roots, and only one was quite sound. The results obtained with this one root indicate, it is to be hoped, what may happen to stored roots rather than what usually takes place.

The manures applied each year to Plot 20 consist of dung (14 tons per acre), basic slag, and sulphate of potash. The yield of roots in 1899 was 9 tons 7 cwt. per acre, being very much below the average.

Particulars of the storage of the selected roots have already been given. The number and average weights of the roots

Changes in Composition of a single Mangel kept for a year. 141

analysed in November, 1899, and the weight of the root from the clamp in November, 1900, were as follows :—

The analytical results in Table II., on page 140, show very remarkable changes in the composition of the root after storage for a whole year, especially when it is remembered that the root had undergone no visible change whatever, and was not only normal in appearance, but also quite hard. The stored root contained less than 6 per cent. of dry matter instead of more than 11 per cent., whilst the percentages of ash and of total nitrogen in the dry matter rose from 8:43 and 1·90, to 18-69 and 4-369 respectively. In the fresh root the total sugar fell from 7.11 to 1.03 per cent., and the remaining sugar was almost entirely invert sugar.

Calculated as percentages of the original weight of the root (estimated by means of the ash percentage), the results show à loss of 87.5 per cent. of the sugar, 20 per cent. of the crude fibre, and 45 per cent. of furfuroids, but no loss of total nitrogen. The nitrogenous matter was, however, a good deal altered, half of the digestible proteids being converted into non-proteids; the indigestible proteids remained essentially the

same.

With only one root available the calculation of its original weight by means of its percentage of ash alone is of course not altogether to be depended on. Taken, however, in conjunction with the determinations of total nitrogen, it is fairly safe to conclude that while the losses indicated in Table II. may have been greater, they cannot very well have been less.

Rothamsted Experiment Station,
Harpenden.

N. H. J. MILLER.

142

THE MANURING OF GARDEN AND
ALLOTMENT CROPS.

ANY attempt to demonstrate the usefulness of manures would be superfluous. Employed at first in an indiscriminate manner, and as the result of traditional experience, they have been, during the course of the last century, the object of systematic study that has led to their rational and economic application. Agriculture has been largely benefited by the progress of science and there are now few farmers who do not recognize the value of manures. Horticulture appears, however, to have somewhat lagged behind in this movement. the same time, numerous works have been published, the conclusions of which I shall endeavour to give after having first entered upon certain considerations of a somewhat general kind, but necessary to explain the principles upon which the use of manures is based.

At

Every one knows that plants derive from the soil the greater number of the elements of which they are composed. With certain exceptions, such as carbon, a small quantity of nitrogen fixed by the leaves, &c., all the elements come from the soil and are absorbed through the roots. Nitrogen, phosphorus, potassium, calcium, and magnesium, are absolutely essential to vegetation, and must be applied to soils in which they are deficient. Other elements, such as sulphur, chlorine, silicon, sodium, iron, and manganese, are usually found in abundance in all soils, so that it is rarely necessary to apply them artificially.

Farmyard manure contains all the essential elements of a good fertiliser, but in very small quantities; and if used in gardens it is because of its usefulness for the formation of beds, and also because it supplies to the soil the humus of which it has need. Mineral elements are not furnished by chemical manures in a pure state, but in the form of combinations

Application of Manurial Elements.

143

which must break up in the soil in order that the constituent elements may be assimilated by the roots of the plants.

The materials most generally employed are as follows:

1. To furnish lime :

Slaked lime; chalk (carbonate of lime); marl; gypsum (sulphate of lime).

2. To furnish phosphoric acid :—

Basic slag; precipitated phosphate of lime; superphosphate of lime; bones.

3. To furnish nitrogen :

Nitrate of soda; nitrate of potash; sulphate of ammonia.

4. To furnish potash :

Nitrate of potash; sulphate of potash; chloride of potassium. 5. To furnish magnesium :-

Sulphate of magnesia.

6. To furnish iron :Sulphate of iron.

Before dealing with the cultivation necessary for special crops, I propose to give some general rules for the employment of manures in horticulture, as recommended by M. Joulie1:—

"The elementary substances that are indispensable may be divided into two categories, which it is important should be carefully distinguished, and of which the method of application must be different. The first category comprises calcareous and phosphatic products. They are insoluble, or nearly so, in pure water, and may be introduced into the soil in large quantities without injury, excepting the superphosphates, which are acid, and may damage the roots if employed on soils incapable of transforming them into neutral substances not easily soluble. They ought never to be employed except in soils sufficiently calcareous to neutralise them immediately they come into contact. They are then transformed into precipitated phosphate of lime, and perform their proper function.

"Every soil may be deemed calcareous that gives rise to a marked effervescence when treated with hydrochloric acid. diluted to a tenth of its volume with water. Such soils as these, containing a large proportion of carbonate of lime, need not receive any calcareous manures. The calcareous substances mentioned should be restricted to soils which give rise to no effervescence on the application of hydrochloric acid diluted with water to a tenth of its volume, and which soils it is therefore

Les Engrais en Horticulture. By MM. Joulie et Desbordes, page 81.