1. That exclusive of blood, sheep’s dung gave the greatest increase in the barley crop. The favourite Norfolk system of eating off turnips with sheep previous to barley, besides other benefits which are known to attend the practice, may owe part of its acknowledged utility to this powerful action of sheep’s dung upon the barley crop.

2. The action of cow dung upon oats is equally striking, and the large return obtained by the use of vegetable manure alone—thirteen fold—may perhaps explain why in poorly farmed districts oats should be a favourite and comparatively profitable crop, and why they may be cultivated with a certain degree of success on lands to which no rich manure is ever added.

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,41lbs.34lbs.
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.
Manure. Starch. Gluten. Starch. Gluten.
Blood,66½6½60  5½
Night-soil,66  6½60  5  
Sheep dung,66½6½61  4½
Horse dung,66  6½61½4½
Cow dung,69   3½62  3½
Vegetable manure,69  3  66½2¼
Unmanured,69½3  66½2¼