WHEAT. Wheat belongs to the Hordea tribe of the Graminca or grass family. There are four principal kinds of sub-races : common wheat (Triticson sotition re/gore), Egyptian and English wheat (Triticent satitotan turgi duns), flint wheat (Triticarn SOilt11118 durum), to which the durum and macaroni varieties be long, and a dwarf variety (Triticum :Gamut compocrum), supposed to have been the kind produced in ancient times. Each sub-race is in turn divided into many varieties. The wheat most generally cultivated and in most common use for bread purposes is Triticum minion vulgar,, although varieties of durum and spelt are extensively grown in some localities.
Wheat is of ancient origin and was culti vated by prehistoric races, as the Swiss Lake Dwellers. In the earliest writings it is men tioned and samples which are not materially different from similar modern varieties have been found in a fair state of preservation in an cient tombs. Attempts have been made to ger minate this wheat.' but without suc cess. The Chinese claim that wheat was used by them as food 2,700 years before the Christian era and in Egypt its use as food appears even to antedate this period. A number of varieties have been cultivated from early times, as spelt, durum, and winter and spring varieties of Triticum sativunt vulgare. Wheats produced in different countries have been subject to dif ferent climatic and soil conditions as well as to different methods of cultivation until material changes have taken place and numerous hard and soft varieties have been produced. There appears to be no authentic record of wheat growing wild and sowing itself without the help of man.
The world's wheat crop normally amounts to about 3,750,000,000 bushels, of which the European countries produce a little more than half. At present the United States is the great est wheat-growing country — about 850,000,000 bushels are produced annually. In 1915 the yield was about 1,000,000,000 bushels. There are large wheat areas in the northwestern pos sessions of British North America which have not yet been brought under full cultivation.
There also are large undeveloped wheat regions in South America, particularly in the Argentine Republic, and it is claimed that some undevel oped parts of Siberia are suitable for wheat production. Thus it is evident that there are vast areas of fertile virgin soil yet to be brought under wheat cultivation.
Wheat can be grown on a variety of soils. It thrives best, however, and produces largest yields upon rich alluvium, and soils formed from different kinds of rock thoroughly disin tegrated and mixed with vegetable mold. The wheat soils of the northwestern wheat region of the United States are largely of glacial for mation and composed of clay and silt with small amounts of fine sand containing liberal amounts of alkaline matter, particularly disin tegrated limestone. The best wheat soils are rich in humus (decaying vegetable matter), which through decay supplies nitrogen, one of the principal elements used by the wheat plant fur the formation of gluten.
The tendency in wheat farming upon new sods has been to grow the crop for a number of )(ars without practising rotation or using fer tilizers After a time this results in reduced sields and an inferior crop, due in part to the loss of nitrogen from the land. Wheat does not remove a large amount of gross fertility from the soil, but exclusive wheat culture on virgin soil causes a rapid decay of the humus and a consequent loss of nitrogen, one of the elements of which humus is composed. %%len wheat is grown along with other farm crops in a good rotation and manures are intelligently used the wheat does not have an exhausting effect upon the soil. The chemical compo sition of a wheat soil of high productiveness from the Red River Valley of the North is as follows: The yield of wheat ranges from 10 bushels and less to 30 bushels and more per acre. la countries where land is expensive, and intensi fied farming is practised, the yield per aere is generally larger than in new regions where more land is available. The yield per acre of wheat in the United States is much less than the soils are capable of producing.