Manures peculiarly adapted to the object, will tend in the highest degree to produce the greatest quantity of _gluten_, the most valuable portion of the flour. It is true, that climate has much to do in condensing, and of course, improving the value of wheat. It is a general principle, that the warmer and drier the climate where it is grown, the more valuable the grain. Wheat from the south of Europe, is worth more than when grown in the north; and that from any portion of the United States, owing to our superior dryness of climate, is more nutritive than what is produced in Great Britain. This difference is increased from 8 to 14 per cent. in favor of the American. Gluten varies in wheat from 8 to 35 per cent.; in rye, 9 to 13; barley, 3 to 6; and oats 2 to 5. The _quality_ of wheat with regard to the quantity of gluten it contains, is nicely estimated and fully regarded by accomplished bakers.
The nitrates of potash, or soda, are frequently used in England to increase not only the quantity, but especially the quality of their flour, a practice the high prices of land and produce may render profitable there, though it is hardly to be expected they could generally be used in this country to a profit. In an experiment lately tried in England, one acre of wheat dressed with one cwt. of nitrate of soda, gave 42½ bushels, weighing 60¾ lbs. per bushel; another acre dressed with two cwt. yielded 47-3/8 bushels, weighing 60½ lbs.; while an undressed acre, in every other respect similar to the others, yielded only 27-7/8 bushels, weighing 61 lbs. Numerous other instances could be given equally conclusive.
Although we may not be justified in using these somewhat expensive salts, so highly charged with nitrogen, there are sources of supply within our reach, especially rich in this material, and abounding in many of the other ingredients of fertility. These are animal manures of all kinds, but more particularly urine, human excrements, and the offal of animals, such as uncalcined bones, horns, hair, hides, flesh, blood, &c. All of these contain large proportions of nitrogen, and if carefully incorporated into the soil, would tend largely to the increased production and value of the wheat crops throughout the country. An experiment was made in manuring wheat with cow dung, which contains the smallest proportion of nitrogen, and this yielded 11·95 per cent. of gluten. Another parcel, grown on land manured with human urine, gave 35·1 per cent. Thus it will be seen, that the maximum of value in wheat, may be reached, by the application of an article, almost everywhere wasted in the United States.