^ Craps. 181 



tice, much better than burning, is to compost such material with 

 soil. In this way, both nitrogen and the ash constituents are 

 conserved as the organic matter decays. 



Individual characteristics of crops may be taken up now more 

 in detail. 



Wheat. This important grain represented 25 per cent of the 

 value of cereal crops and 13 per cent of all crops in 1900. Sixty- 

 two per cent of the cereal products milled in that year were from 

 wheat. Over one-third of the farms in the United States raised 

 wheat, with a total production in 1900 of 35 billion bushels. 

 Extensive breeding of this grain has led to the production of 

 about 245 leading varieties. 



The crop is commonly sown in the fall and grown as "winter 

 wheat." As a result, it has a longer period of growth and a 

 more extensive root system than most of the cereals. The roots, 

 which are especially developed in Durum wheat, have been found 

 to reach a length of four, and even of six feet. These conditions 

 enable the plant to feed effectively upon the soil. The necessary 

 omission of spring tillage in the case of this crop, prevents the 

 aid of this important stimulus to nitrification and renders wheat 

 dependent largely upon manurial supplies of available nitrogen. 

 Its extensive root system and long period of growth aid this plant 

 in deriving its mineral constituents from the soil and make it 

 more independent of available potash or phosphate fertilization ; 

 nitrates or ammonium salts consequently are recommended as the 

 chief fertilizer treatment. 



The wheat kernel, according to Bessey, is separated mechan- 

 ically into the following proportion of parts : 



Coatings (or bran layers) 5 per cent 



Gluten layer 34 " 



Starch cells 8486 



Germ 6 " 



Protein and fat are highest in the germ and bran, ash is high- 

 est in the bran, and the fibre is confined almost exclusively to 

 this coating. Starch is the characteristic, and by far the most 



