CHAPTER I 



COMPOSITION OF PLANTS 



How Plants Make Food. Plants supply the feed for 

 poultry and a brief description of their composition and 

 growth is of value in the study of the principles of poultry 

 feeding. Fourteen elements are commonly found in 

 plants, namely, carbon, hydrogen, oxygen, nitrogen, phos- 

 phorus, sulphur, calcium, potassium, iron, magnesium, 

 sodium, chlorin, silicon and manganese. The water 

 which is obtained from the soil through the roots of plants 

 makes up from 75 to 90 per cent of the weight of freshly 

 cut plants. In addition to the water which they use plants 

 live largely on carbon dioxid drawn from the air. 



Plants use an enormous volume of air in getting this 

 carbon dioxid as only 3 to 4 parts of carbon dioxid are 

 found in 10,000 parts of air. Practically all plants ex- 

 cept the legumes secure their nitrogen from the soil either 

 in the form of nitrates or as ammonia. The legumes in- 

 cluding such plants as clover, alfalfa, soybeans and cow- 

 peas are able to take nitrogen gas from the air through 

 nodular growth on their roots which contain bacteria. 

 Therefore, the growing of these legumes adds fertility 

 directly to the soil in the form of nitrogen. The mineral 

 substances of plants given in this list of elements are taken 

 from the soil in the form of phosphates, sulphates, car- 



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