CHAPTER XI. 



MANURING. 



Of all the operations connected with the growing of 

 citrus fruits tho subject of manuring is one of the most 

 important. However rich the soils may naturally 

 be, through continual cropping they will, sooner or 

 later, become impoverished, unless sufficient fertiliser 

 is applied to the ground to replace the plant food 

 removed. The elements which enter into the 

 composition of plants are carbon, oxygen, nitrogen, 

 hydrogen, potassium, calcium, magnesium, phos- 

 phorous, sulphur, and iron. Of these, all except 

 nitrogen, potash, phosphorous, and sometimes lime, 

 are usually present in sufficient quantities for the 

 needs of the trees. 



Young citrus trees require a liberal supply of 

 nitrogen if they are to make vigorous wood growth. 

 When the trees come into bearing very large amounts 

 of nitrogen are no longer necessary, as they impair the 

 fruitfulness of the trees, wood formation taking place 

 at the expense of fruit. Citrus trees of all ages 

 should always be supplied with a liberal supply of 

 phosphoric acid (phosphates) or the health of the tree 

 will suffer, and the fruit will not develop normally. 

 For the formation of citrus fruits a plentiful supply 

 of potash is essential. Harold Hume, of the Univer- 

 sity of Florida, the American citrus expert, says of 

 potash manuring in respect to citrus trees : "If 

 large amounts of potash are taken up by the trees 

 it will be found that the rind of the fruit will be much 

 thinner than otherwise and the amount of rag will 

 be greatly lessened. A plentiful supply of potash 

 in the fruit has an excellent influence on its keeping 



