Practical methods of improving seed wheat.
It is contended that the larger grains found in any variety are cap able of increasing the yield, and many experiments go to show that this is a fact. It is probable that size alone cannot be depended on, but rather weight of the grain. For this reason a machine has been devised to take the place of the screening machines usually em ployed. This machine has a cylinder which throws the grain by centrifugal force. The heavier grains naturally travel the farthest and the grain is graded by a series of receptacles into which it falls. Screening either by the use of a fanning mill or a perforated cylinder is also a good practice.
Other factors enter into the improvement of wheat. Among these will be its treatment for pre venting smut and the use of fertilizers. It may also be benefited by being changed to a more con genial climate or soil.
Soil.
Wheat grows in a very great variety of soils, ranging from the stiff clays of the New England region to the volcanic ash of the Pacific coast. With such a great variation no set rule or method for preparation can be advised. In general, soils which are full of organic matter, loose in texture and dark in color are not so well suited for wheat growing as the lighter clay and drift soils. As a rule, over much of the area devoted to wheat-grow ing, crop rotation or the use of some amendment to the soil is essential. In regions where this is not followed it is often customary to practice what is known as summer-fallowing.
Land intended for winter wheat should be plowed as early in the preceding season as possible. This permits of more thorough preparation of the soil and also of the absorption of moisture during the summer. Surface cultivation should be followed, particularly after each rain. The depth of the plowing should not be less than four inches nor more than eight inches. In regions where corn is a leading crop it is customary to seed such fields without replowing, specially designed tools for pre paring the soil and seeding between the rows of corn being used. This allows of the economical use of the land, and the crops secured are gener ally equal to those secured by more expensive methods of preparation. Fig. 902 shows a field
terraced to prevent soil washing.
When spring wheat is grown, the land should be plowed in the fall preceding or as soon as possible in the spring. Thorough preparation of the soil is important in all cases.
Fertilizers. (T. L. Lyon).
On the older soils of the eastern states, extend ing as far west as Ohio and Kentucky, barnyard manure or commercial fertilizer is commonly applied to the land for wheat or for some crop in the rotation of which wheat forms a course. The same is true of eastern Canada, including the prov ince of Ontario. \Vest of this, commercial fertili zers are used very little, although barnyard manure is used on grass-land and for cultivated crops in all the country lying east of the semi-arid region. On the light soils of the prairie region barnyard manure plowed under immediately before seeding to wheat is likely to make the soil too loose for the best yield of that crop.
Summer-fallowing is practiced extensively in the semi-arid regions, where the crop is not irrigated. A considerable proportion of the wheat of North America is now produced in regions having an annual rainfall of less than twenty inches. The soil of these regions is usually very deep, so that there is little loss of moisture by percolation ; almost all of the rainfall that does not run off the surface or pass through the tissues of the plant is lost by evaporation from the soil. The effect of the summer-fallow is to conserve a large part of the rainfall during the year the land is kept fal lowed, and thus greatly to increase the suoply of soil moisture for the following crop. In very dry regions it is customary to fallow every other year, but where the rainfall is not so meager, two or three crops intervene. Summer-fallowing is very destructive to the humus, but it increases the supply of easily soluble plant-food materials, and these, with the greater moisture supply, produce much larger crops than can be secured when the land is cropped continuously. Barnyard manure cannot be used in this region for the wheat crop.