CULTURE OF WHEAT 7i 



mg to death and by being heaved out by alternate freezing and 

 thawing. When the soil is bare, the soil temperature about the 

 roots of the young plant will reach nearly that of the overlying air, 

 while if covered with two inches of snow the soil may, if the low 

 temperature is of short duration, be little if any below freezing. 



II. THE SOIL AND ITS AMENDMENTS. 



115. The Choice of Soil. — The character of the soil affects 

 the yield much more than the quality of the wheat. (74, iii) 

 A large proportion of the wheat is grown in this country upon 

 glaciated drift soil, the controlling reason being the ease of 

 cultivation and adaptation to the use of light machinery. 



Throughout the winter wheat region between parallels 38° 

 and 42° N. latitude, within which lies what is known as the 

 "Corn-belt," two general types of drift soil are recognized: (i) 

 clay soils, usually upland, light in color, tenacious in texture, 

 requiring careful tillage, which is generally adapted to wheat 

 and grass crops, and (2) loamy soils, usually lowlands or prai- 

 ries, dark in color, full of organic matter and friable in texture, 

 generally known as maize land, to which it is especially adapted. 

 This latter is not so well adapted to wheat, because in unfavor- 

 able seasons the wheat is apt to winter kill. Where the first 

 type of soil is predominant, wheat, meadows and pastures 

 largely prevail, while where the second type is predominant, 

 maize and oats are the prevailing crops. It is not so much that 

 fair crops of wheat may not be obtained as it is that maize pays 

 better that has brought about this result ; although on this soil 

 wheat, as just stated, is very liable to winter kill. On the other 

 hand, on the clay soils maize not only does not do so well, 

 but the grass crop reduces the labor of tillage and helps to 

 maintain the fertility of the soil. There is still a third type of 

 soil to be found in less quantity in river valleys, chocolate in 

 color, less tenacious in texture than the upland clays, being 

 composed of a larger proportion of silt than the clay and less 



