CHAPTEE XII. 

 CROPS. 



IN this chapter will be given a short account of the chemical char- 

 acteristics of the chief crops of the farm. Some of the crops described 

 cannot be grown successfully in temperate climates, e.g., England, but 

 are included because of their importance as food stuff's. A brief de- 

 scription of the chemistry of some of the more important fruits is 

 also embodied. 



Crops may be grouped according to various methods. The follow- 

 ing classification will be adopted here : 



1. Those in which the seed (or fruit) is the portion of the plant 

 most valued. 



These may be sub-divided into 



(a) Cereals wheat, barley, oats, rye, maize, rice, millet, 



sorghum. 



(b) Leguminous seeds beans, peas, lentils, lupines, earth nuts, 



soy beans, cow peas. 



(c) Miscellaneous seeds buckwheat, cottonseed, linseed, hemp- 



seed, rape seed, castor seed, sunflower seed. 



(d) Fruits apples, pears, plums, apricots, peaches, cherries, 



currants, citrus fruits, melons, pumpkins, grapes, bananas, 

 pine-apples. 



2. Those in which the root or tuber is the most valued product 

 turnip, swede, mangold, beet, potato, carrot, parsnip, sweet potato, 

 artichoke. 



3. Those in which the stem and foliage are of most importance. 

 These include 



(a) Gramineous crops. 



(b) Leguminous fodder crops. 



(c) Miscellaneous fodder crops. 



CLASS 1. GRAIN CROPS AND FRUITS. 



(a) The Cereals. These are characterised by containing much 

 less nitrogen than leguminous or root crops, and by the richness of 

 their seed in carbohydrates, particularly starch. 



They are also remarkable for the large amount of silica which is 

 usually present in the outer portions of the leaves and straw. This 

 silica, which is apparently not essential, is absorbed as soluble silicates, 

 the rnetals, probably chiefly potassium, being used in the plant, the 



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