48 



THE BOOK OP WHEAT 



tenacious clay; and the lowlands and prairies, which have a 

 dark, loamy, organic, friable soil. Common bread wheats are 

 usually grown on black soils. These soils are not well adapted 

 to fall wheat, however, for it is apt to winterkill. Durum wheats 

 thrive best in alkaline soils rich in nitrogenous matter. Sandy 

 bottom land is best adapted to the production of soft wheat. 

 Richardson attributed the low protein content of some American 

 wheat to a deficiency in soil nitrogen. The ash of wheat stands 

 next to the gluten in variability, and the factor most concerned 

 in its variation is the soil. 



DURUM WHEAT DISTRICTS OF THE UNITED STATES 

 (By Carleton) 



The lined districts show where durum wheat will succeed best and the dotted 

 districts where it may be grown with grain of less quality. 



Climate. Seasonal differences are included under this sub- 

 ject, because their effects are the same in kind as those of 

 climatic differences. Certain climates produce certain cor- 

 responding characteristics in wheat, regardless of what the soil 

 conditions are. The protein content of wheat, and correspond- 

 ingly its moist and dry gluten, is extremely sensitive to en- 

 vironment of a meteorological nature. The starch content is 

 also sensitive, but in an inverse ratio. Climate varies from 



