In this country wheat is not cultivated, that is, there is no cultivation of the soil after seeding. The soil is, however, plowed and harrowed before planting. In the winter wheat regions the harvesting is in the month of June, though in the southern localities it comes somewhat earlier and in the more northern localities may extend into July. In the spring wheat regions the harvesting is from the last of July to the middle or end of August. The statistics of wheat grown in the United States during 1906 are as follows:
| Winter. | Spring. | |
|---|---|---|
| Acreage, | 29,599,961 | 17,705,868 |
| Yield per acre (bushels), | 16.7 | 13.7 |
| Total yield (bushels), | 492,888,004 | 242,372,966 |
| Total value at farm, | $336,435,081 | $153,897,679 |
| Price per bushel (cents), | 68.3 | 63.5 |
All the different varieties of wheat which are now known are cultivated. The simplest form, namely, the one grain wheat is the only one which grows wild, and the origin of the other varieties of wheat is unknown.
Botanists recognize three species, namely—Species 1, one grain wheat (Triticum monococcum Lam.); species 2, Polish wheat (Triticum polonicum L.); species 3, common wheat (Triticum sativum Lam.). All of these species are distinct, especially the third one, of which the most valuable variety is the common wheat, Triticum vulgare Vill.
The quality and properties of wheat depend more upon the environment in which it is grown than upon the species to which it belongs. There is perhaps no other field crop in which the environment, namely, condition of the soil, temperature, precipitation, etc., makes a greater difference than in wheat. In general, the environment and the species together produce two kinds of wheat as far as milling and bread making are concerned, namely, the soft or starchy wheat and the hard or glutinous wheat. In the first variety there is a larger percentage of starch in relation to the content or protein matter than in the second. Taking the wheat as a whole its average composition is shown in the following table:
| Weight of 100 kernels, | 3.85 | grams |
| Moisture, | 10.60 | percent |
| Protein, | 12.25 | „ |
| Ether extract, | 1.75 | „ |
| Crude fiber, | 2.40 | „ |
| Ash, | 1.75 | „ |
| Carbohydrates other than crude fiber, | 71.25 | „ |
| Dry gluten, | 10.25 | „ |
| Moist gluten, | 26.50 | „ |
In regard to protein American wheat, as a rule, is quite equal to that of foreign origin. This is an important characteristic when it is remembered that both the milling and food value of a wheat depend largely upon the nitrogenous matter which is present. It must not be forgotten, however, that merely a good percentage of protein is not of itself a sure indication of the milling value of a wheat. The ratio of gluten to the other protein constituents in a wheat is not always constant, but it is the gluten content of a flour on which the bread making qualities chiefly depend.
Gluten.
—The principal part of the protein in wheat is known as gluten. Gluten as such does not exist in the wheat but is formed when the pulverized wheat, that is, the wheat flour, is mixed with water by the union of two elements in the wheat, namely, gliadin, which is soluble in dilute alcohol and forms nearly half of the whole protein matter of the wheat kernel, and glutenin, a compound insoluble in water, dilute salt solutions, and dilute alcohol and which is quite as abundant as gliadin in the wheat kernel. In fact, the gliadin and the glutenin together make the whole of the protein, except a little over one per cent.
There are three other forms of protein, as pointed out by Osborne, in the wheat kernel, making altogether nearly 11⁄2 percent of total protein content. The average quantity of these compounds in the protein of wheat is as follows.