51 



EFFECT OF FERTILISERS ON THE ORANGE IN HEALTH. 



The elements which need to be supplied in fertilisation to most 

 Florida orange groves are nitrogen, potassium, and phosphorous ; or 

 using the terms in which they are expressed in most analyses of ferti- 

 lisers, ammonia, potash, and phosphoric acid. The application of lime 

 would also prove of benefit to many groves. Probably no element of 

 plant food used in the fertilisation of orange groves should be more 

 •aref ully considered, with respect both to form and quantity, than nitro- 

 gen. It is the most costly and at the same time the most dangerous 

 element to use, as excessive applications are liable to resist in extensive 

 dropping and splitting of the fruit or in the production of the serious 

 diseases known as die-back, which will be discussed below. 



EFFECT OF NITROGEN. 



A Grower may with considerable certainty determine by the appear- 

 ance of his trees the condition of his grove in respect to the supply of 

 nitrogen available in the soil. An abundance of nitrogen is indicated 

 by a dark green colour of the foliage and rank growth. The fruit shows 

 the effect of an abundance of nitrogen by being, in general, large, with 

 a thick and comparatively rough rind. If the trees have a yellowish 

 foliage, with comparatively small leaves, and show little or no growth, 

 there is probably a lack of nitrogen. In this case there is but little 

 fruit fermed, and that formed is small and usually colours early. If the 

 tree is starving from a lack of nitrogen, the foliage will become very 

 light yellow and sparse, and the small limbs will die, as will also the 

 large limbs in extreme cases. If the starvation is continued, no fer- 

 tiliser being added, the tree will finally die back nearly to the ground 

 and probably die out entirely. The extreme symptoms of general star- 

 vation from lack of elements are probably nearly the same. lhe 

 nitrogen used in fertilisation is commonly derived from mineral or 

 organic sources. Of the former, sulphate of ammonia and nitrate of 

 soda are the forms most used; of the latter, muck, dried blood, blood 

 and bone, cotton-seed meal, tankage, fish scrap, stable manure, etc., are 

 the forms most commonly employed. 



INJURIOUS ACTION OF MUCK. 



Muck is very commonly app lied in considerable quantities either in a 

 raw state or composted with sulphate of potush, etc. Many growers 

 rather fanatically hold to what they term natural fertilisation. By this 

 is usually meant giving the tree nourishment in the form in which they 

 suppose it to bo derived in nature. It is contended by many that muck 

 is principally decaying vegetable matter, and that as this is the form 

 of nourishment which the trees obtain in nature, it must be a good fer- 

 tiliser to use in culiivation. But it must be borne in mind that orange 

 trees as we cultivate them are decidedly not in a state of nature, except 

 that by the cultivation of centuries we have made cultivation and manur- 

 ing natural conditions which the plant demands. Trees in nature bear 

 fisuits for seed to reproduce the species ; on the contrary, we grow fruits 

 for market and favour a seedless variety. We want a smooth, thin- 

 skinned, tender, juicy fruit that will sink in water. Nature does not 

 paj particular attention to these characters, so we watch for freaks and 

 sports, abnormal plants, which have the characters we desire, and when 

 found we render these characters permanent by budding. Our aim in 



