244 CHAPTER XIV 



From this it will be seen that the difference in climate 

 was a dominating factor. 



However, the soil does influence the composition, but in 

 general farm practice to only a comparatively small degree. 

 The protein in wheat may be increased by high nitrogenous 

 manuring. Hall, at Kothamstead, has obtained wheat in this 

 manner so high in gluten that it was almost impossible to 

 obtain the ordinary baked loaf, the dough being loose, unstable 

 and gelatinous. 



In Ohio a number of experiments was conducted to 

 ascertain the effect of fertilisers on the physical and chemical 

 properties of wheat. ^ The soil on which the experiments 

 were carried out was very unproductive, normally, 50 per cent, 

 of the grain was shrivelled and undeveloped. By increasing 

 the nitrogen content alone of the soil, this condition of the 

 kernels was accentuated. 



Potash gave a larger percentage of plump kernels, but the 

 composition w^as about the same as that found in the nitrogen 

 plots. Phosphates improved the physical appearance of the 

 grain to the greatest extent. The nitrogen plots gave wheat 

 of a higher protein content because of the shrivelled grain 

 produced, while the grain from the plots manured with phos- 

 phates gave wheat having a higher carbohydrate content, 

 because of the plumper grain produced. 



When the soil deficiencies are remedied by judicious 

 manuring the most satisfactory kernels are produced. 



The following correlations have been noted in this 

 respect : — * 



(1) The average weight of the kernel varies directly with 

 the length of the development period. 



(2) The percentage nitrogen varies inversely with the 

 length of this period. 



(3) The length of this period is the chief determining 

 factor in the final composition of the grain. 



(4) A relatively high rainfall, particularly between flower- 

 ing and ripening, results in the wheat being lower in protein 

 and higher in starch than when the opposite is the case. 



The following shows he average constituents taken to 

 form an ordinary crop of wheat in Australia : — 



