Section Ii.—Influence of the Kind of Manure on the Chemical Quality of

THE GRAIN.

But the quality of the grain also, as well as its quantity, is materially affected by the kind of manure by which its growth is assisted. The apparent quality of wheat and oats is very various; but in samples apparently equal in quality, important chemical differences may exist, by which it is believed that the nourishing properties of the grain are materially affected.

It has been stated in a previous chapter (p. 43), that when flour is made into dough, and this dough is washed upon a linen cloth with water as long as the latter passes through milky,—the flour is separated into starch, which subsides from the water, and gluten, which remains behind. The quantity of gluten thus left varies more or less with almost every sample of flour, and the nutritive properties of each sample are supposed to depend very much upon the quantity of gluten it contains. So far it seems to be pretty well ascertained, that those varieties of grain which contain the largest amount of gluten yield also the greatest return of flour, and the heaviest weight of bread.

The weight of gluten contained in 100 lbs. of dry wheat has been found to vary from 8 to 34 lbs., and this proportion is affected in a very remarkable manner by the kind of manure which has been applied to the land. Thus the proportions of starch and gluten in 100 lbs. of the grain of the same wheat, grown on the same land, differently manured, was as follows:—

Manure. Starch. Gluten. Blood, 41 lbs. 34 lbs. Sheep’s dung, 42 ” 33 ” Horse dung, 62 ” 14 ” Cow dung, 62 ” 12 ” Vegetable manure, 66 ” 10 ”

Potato-flour, which consists entirely of starch, makes a fine light bread, easily raised. Wheaten-flour, which contains little gluten, approaches in this respect to potato-flour. When the quantity of gluten is large, greater care is required to make a good light bread; but the bread from such flour is generally found to be more nutritive in its quality. A dough peculiarly rich in gluten is required for the manufacture of macaroni and vermicelli; such is said to be the flour naturally produced in southern Italy. By the above table it appears, that the use of richer animal, or poorer vegetable manures, would enable the farmer to raise, at his pleasure, either a rich macaroni wheat, or one poor in gluten suited for the makers of fancy bread.

An equally striking effect is not produced upon other kinds of grain by varying the manure. Thus the proportions of starch and gluten in the dry grain of barley and oats, differently manured, were found to be as follows:—

BARLEY. OATS. Starch. Gluten. Starch. Gluten. Blood, 66½ 6½ 60 5½ Night-soil, 66 6½ 60 5 Sheep dung, 66½ 6½ 61 4½ Horse dung, 66 6½ 61½ 4½ Cow dung, 69 3½ 62 3½ Vegetable manure, 69 3 66½ 2¼ Unmanured, 69½ 3 66½ 2¼

Though a variation in the proportion of gluten can be observed in both of these kinds of grain, according as one or other of the above kinds of manure was employed, yet neither the average quantity of gluten present in them, nor the variations to which the quantity is liable, are at all equal in amount to what are observed in the case of wheat.

The malting of barley is known to be affected by a variety of circumstances. It should be so uniform in ripeness as to sprout uniformly, so that no part of it should be beginning to shoot when the rest has already germinated sufficiently for the maker’s purpose. On this perfect sprouting of the whole depends in some degree the swelling of the malt, which is of considerable consequence to the manufacturer.

But the melting quality of the grain, which is of more consequence to the brewer and distiller, is modified chiefly by the proportion of gluten which the barley contains. That which contains the least gluten, and therefore the most starch, will melt the most easily and the most completely, and will yield the strongest beer or spirit from the same quantity of grain. Hence the preference given by the brewer to the malt of particular districts, even where the sample appears otherwise inferior. Thus the brewers on the sea-board of the county of Durham will not purchase the barley of their own neighbourhood, while Norfolk grain can be had at a moderate increase of price. But that which refuses to melt well in the hands of the brewer, will cause pigs and other stock to thrive well in the hands of the feeder, and this is the chief outlet for the barley which the brewer and distiller reject.

So far as a practical deduction can be drawn from the effects of different manures on the proportion of gluten in barley, it would appear that the larger the quantity of cow dung contained in the manure applied to barley land—in other words, the greater the numbers of stock folded about the farm-yard, the more likely is the barley to be such as will bring a high price from the brewer.

The folding of sheep produces a larger return (p. 206), from the barley crop—while the folding of cattle gives grain of a better malting quality.