WHEAT. The botanical characters of wheat will be found under the word Turner:at, in Ner. Hisr. Div. Some botanists have divided wheats into different species, from some marked peculiarity in their formation. Others, considering that they mostly form hybrids when mixed in the sowing, and that their peculiarities vary with the soil and climate, have looked upon all the cultivated wheats as mere varieties. There are, however, three principal varieties, so different in appearance that they claim peculiar attention. These ere the hard wheats, the soft wheath, and the Polish wheats. The hard wheats are the produce of warm climates, such as Italy, Sicily, and Barbary. The soft wheats grow in the northern parts of Europe, as in Belgium, England, Den mark, and Sweden. The Polish wheats grow in the country from which they derive their name, and are also hard wheats. It is from their external form that they are distinguished from other wheats. The hard wheats have a compact aced nearly transparent, which, when bitten through, breaks short, and shows a very white flour within. The soft wheats are those usually cultivated in Britain : they have an opaque coat or skin, which, when first reaped, gives way readily to the pressure of the finger and. thumb. These wheats require to be well dried and hardened before they can be conveniently ground into flour. The Polish wheat has a long chaff which is much longer than the seed, a large oblong hard seed, and an ear cylindrical in appearance. It is a delicate spring wheat, and not very productive in the climate of England : hence it has only been occasionally cultivated by way of experiment.
The following cuts represent some peculiar varieties of wheat. The first is a compound ear, common in Egypt. The second is the spelter wheat, of which the chaff is so strongly attached to the grain as to be separated only by passing through a mill. It is an inferior variety, but grows in less fertile soils. The third is the Polish wheat, with very long chaff and hard grains. The fourth is a variety which only ripen. one seed In each epikelet, and is not much cultivated. The fifth Is common soft bearded wheat. If the awns of this kind are oblite rated, it forms our common soft wheat. The circumstance of awns Seems not to affect the nature of the wheat, and they differ so much in length that the varieties of smooth-eared and bearded wheate run insensibly into each other.
The distinction between the winter and summer wheath is one which arises entirely from the season in which they have been usually sown ; for they can readily be converted into each other by sowing earlier or later, and gradually accelerating or retarding their growths. The original difference in colour between red and white wheats is owing chiefly to the Boil : white wheats gradually become darker and ulti mately red in some dill' wet soils, and the red wheats lose their colour and become first yellow and then white on rich, light, and mellow soils- It remarkable that the grain sooner changes colour than the chaff and straw. Hence we have red wheats with white chaff, and
white wheats with red chaff, which on the foregoing principle is readily accounted for. The chaff retains the original colour when the skin of the grain has already changed to another. We atate this on our own experience. The soil best adapted to the growth of wheat is a deep loam inclined to clay, with a dry subsoil. If this is not dry naturally, it must be drained artificially, to ensure good crops of wheat. In such a soil wheat may be sown every third year, with proper intermediate crops. Formerly the preparation for a wheat crop was generally by a clean naked fallow, with a certain addition of manure, the remains of which were thought sufficient for a crop of barley or oats, after which the fallow recurred. It was soon found out that by this means a crop of wheat could never be forced beyond a certain average ; for if more than the usual portion of manure was carried on the land the wheat failed, by being laid before it arrived at maturity. Thus a limit appeared to have been set to its increase. New modes of cultivation have shown that this was not without its remedy, and that it was recent manuring which caused the wheat to lodge : but that an in creased fertility, produced by judicious preparation, enabled the land to bear crops of wheat far superior to what it ever could before. Wheat requires a soil In which the organic matter is intimately mixed with the earthy ingredients; where it can have a firm hold by its roots, and can at the same time strike the fibres of them downwards, as well as around, in search of food. When it meets with such a soil and is deposited at a proper depth, it vegetates slowly, pushing to the surface oue cylindrical filament, while numerous fibres strike into the soil from the seed. These supply the plant with regular nourishment, and in due time a knot is formed at the surface of the soil, from which several roots and stems branch out. This is called the tillering of the wheat. The new roots near the surface soon become the chief source of nourishment, and in a rich compact soil, where there is room, nume rous stems arise, forming a tuft, and each of these in time bears a large ear well filled with seeds; so that from a very moderate quantity of seed a great return is produced. The strong stems supporting each other are well able to resist the effect of storms and rains, which would lay weaker plants level with the ground. The effect of surface manur ing immediately before the seed is sown is to produce too rapid a growth, weakening the straw, and increasing its quantity often at the expense of the ear, which does not attain its proper development. This is called running to straw. Ammoniacal and nitrogenous manures have this effect ; which is corroborated by late experiments with sul phate of ammonia, saltpetre, and nitrate of soda.