ally rich in phosphoric acid and poor in potash; sandy soils The 



are almost always poor in plant-foods, and soils laden with Cultlvatlon of 



u u . u A '4. Citrus Fruits 



organic matter rich in humus contain abundant nitrogen, . 



although it is not always in a form in which it is assimilable i s 



by plants. 



The typical formula will have, therefore, to be modified, 

 more or less, according to the nature of the soil; the elements 

 which are deficient or abound in the latter being increased 

 or diminished correspondingly. As a general rule, all soils 

 are deficient in phosphates, and therefore it will almost al- 

 ways be safe, if not necessary, to increase the quantity of the 

 phosphatic fertilizer indicated in the general formula. 



In the case of trees of the citrus family, an excess of 

 nitrogen induces an exuberant production of wood and leaf, 

 at the same time that the fruit is rendered thick in rind and 

 puffy, deficient in sweetness, wanting in aroma and with a 

 marked tendency to rot. Moreover, a superabundance of 

 nitrogen in the food of the plant delays maturity; and this 

 circumstance has to be taken into account according as early 

 or late maturity of the crop is desired. 



Organic nitrogen, as found in cotton-seed meal, dried 

 blood, guano, barn-yard manure, etc., is especially apt to 

 bring about a soft, rapid growth, and in certain regions, 

 especially in Florida, its continued use is found almost cer- 

 tainly to give rise to "die-back." 



If phosphoric acid is largely in excess in the fertilizer, 

 the fruit will generally be abundant but small, of fine flavour, 

 and having the seeds numerous, large and of great germin- 

 ating power. 



When potash is superabundant relatively to the other 

 available constituents of plant food, the tree acquires but 

 little development; the fruit, however, is juicy, very sweet, 

 of rich flavour and delicate aroma; the rind is fine and the 

 seeds small and few in number. 



From what has been said it will be sufficiently obvious 

 by itself alone the part of a complete fertilizer; each is the 

 complement of the others, each supplements the action of the 

 others, and conjointly and supplied in suitable proportions, 

 they bring about the desired results. 



The general formula which has been indicated pre- 

 supposes that the trees to which the fertilizer is to be applied 

 are large, in full bearing, and yielding a crop of about 



