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PLANT FOOD EEMOVED BY FEUIT 



(d) Fruits. These are hardly to be classed as ordinary farm crops, 

 but as in some countries great importance is attached to "fruit farm- 

 ing," they may receive brief mention and consideration here. As a 

 rule, they are the produce of perennial plants trees or shrubs 

 and are therefore not so amenable to cultivation and manuring as the 

 usual farm crops. Their extensive root development enables them to 

 search for food through a larger mass of soil, so that they will often 

 grow on land which may be too poor in plant food to yield payable 

 crops of the usual farm products. They, nevertheless, draw upon the 

 supplies of plant food in two ways : 



(1) To form their fruit, which is usually removed from the tree and 

 lost to the land. 



(2) To be locked up in the tissues of the trees. The trunk, 

 branches, roots and leaves all require nitrogen, potash, phosphoric 

 acid, lime and other constituents obtained from the soil. In the case 

 of deciduous trees, the falling leaves restore, annually, a considerable 

 portion of plant food to the soil. 



The amount of manurial ingredients removed in fruit is, on the 

 whole, small. American estimates give the following as the weight, in 

 pounds, contained in 1000 Ib. of the fresh fruits named : 



Fruits are usually rich in water and their dry matter often consists 

 largely of sugar, to which their sweetness is due, pentosans, pectins, 

 vegetable acids, of which malic, C 2 H 3 (OH)(COOH) , citric, CH 2 

 (COOH).C(OH)(COOH.)CH 2 (COOH), tartaric, CH 2 .(COOH).CH(OH). 

 CH(OH).CH 2 (COOH) and oxalic acid, COOH.COOH, are the chief, and 

 small quantities of essential oil, to which their characteristic flavours 

 are mainly due. 



The following figures show the average compositions of several of 

 the more common fruits, the free acid being given in terms of malic 

 acid, except in the case of the grape (tartaric acid) and the citrus, 

 fruits (citric acid) : 



