CEBEALS. 241 



season for nitrification begins, they derive great benefit from 

 nitrogenous manures. 



Wheat, being usually autumn sown, has a longer period of 

 growth than barley or oats and is consequently better able to 

 supply itself with the necessary food from the soil. With a 

 wheat crop, however, the land loses the spring tillage, which 

 is conducive to nitrification, and therefore nitrogenous manures 

 are perhaps more required by wheat than by the other cereals. 



Wheat straw is remarkable for the excessively large amount 

 of silica and small amount of nutritive matter which it often 

 contains. 



Wheat is particularly fitted for human food owing to the 

 light, spongy, and palatable bread which can be made from 

 wheat flour. This is due to the richness of the grain in gluten 

 and the peculiarity of this gluten as compared with that occur- 

 ring in the other cereals.* 



Eye very much resembles wheat in its chemical composition 

 and manurial requirements. 



Barley and oats have a much shorter period of growth and 

 hence require an abundance of plant food. Like the other 

 cereals, they can only obtain nitrogen from nitrates ; but the 

 spring tillage in preparing the land for sowing renders it also 

 very suitable for the development of the nitrifying organisms. 

 Moreover, in the case of barley for malting the presence of too 

 much nitrogenous food in the soil favours the production of 

 albuminoids in the grain so as to render it unsuitable for 

 brewing purposes. Consequently nitrogenous manures, in the 

 case of barley, require to be applied in moderation only. The 

 grain of oats is especially rich in ash ; their straws are more 

 nutritious, digestible, and palatable to animals than those of 

 wheat and rye. 



Maize, which is not often grown in England, and then 

 generally for fodder, has the advantage over other cereals of 

 prolonging its growth until late in the autumn, so that it has 

 the opportunity of assimilating the nitrates produced during 

 the hot season. The grain is particularly rich in starch and fat. 

 (b) Leguminous Grain Crops. Beans and peas. The 

 characteristic of these plants is their power of obtaining the 



f. Chap. IX., p. 215. 



