Ill 



three years the plant should be changed to fresh soil. Mr. Bowrej . 

 however, gives the following suggestions as to manuring the pine- 

 apple: — "'Judging from this analysis of the ash of the pine-apple, 



potash is the most important mineral substance which it requires. < H 

 course, phosphoric acid is also necessary, and so are lime, magnesia 

 and iron : but it must be a very rare soil which does not contain iron 

 and magnesia in ample quantity, and usually there is enough lime also 

 present. It is difficult to make suggesl ions respecting manuring in total 

 ignorance of the nature ol the soil to be manured. But certainly no 

 harm can be done and probably much good by adding phosphoric acid 

 and potash to the soil : the former best as finely ground basic slag, 

 price about 55s. per ton f. o. b. in England. A dressing of from five 

 to ten cwts. per acre will supply phosphoric acid for three or four 

 years and also some quantity of lime. The potash can. I think, be 

 obtained here or imported into Jamaica most cheaply as muriate of 

 potash : its price is about £8 per ton, f. o. b. in England. From one- 

 half to one cwt. per acre would be a dressing for a year. But the 

 pine-apple also requires nitrogen for its growth ; this might be 

 supplied as nitrate of soda at £10 per ton, giving one cwt. per acre 

 when the plants have started to grow rapidly." 



The combination of muriate of potash with nitrate of soda in 

 about equal proportions has been regarded by many chemists as a 

 practical method of supplying nitrate of potash cheaply to the soil. 

 The combination is largely used in France in horticulture. It has been 

 recognised that muriate of potash when used alone as a source of potash 

 to a soil deficient in this constituent is liable to failure, and many cas 

 of disappointment occurred in France soon after its introduction 

 mainly on the recommendation of Mr. George Ville. These failures 

 led to an investigation by M. Crochetelle. who finally showed that 

 for the muriate to become assimilable by plants it had first to be con- 

 verted into the carbonate. In the form of carbonate it is readily 

 converted into the nitrate by the agency of the nitrifying organisms 

 contained in the soil. The great fact in the natural history of these 

 organisms is that they live on the element carbon, extracting it from 

 carbonates, and liberating at the same time their oxygen to oxydise 

 nitrogenous compounds into nitric acid and nitrate-. Potash 

 and nitrogen are chiefly taken up by plants in the form of nitrates. 

 The value of chemical manures in the cultivation of the pine-apple is 

 not to be disregarded, because it will be by the aid of nitrate of soda, 

 salts of potash, and preparations of phosphoric acid that the cultivation 

 of the pine on the same ground can be kept up. Mr. Bowrey's advice 

 to employ basic slag must be regarded as valuable, more especially so 

 in the pineries of St. Andrew, where lime appears to be a diffident 

 constituent in some of the fields devoted to the pine-apple. The basic 

 slag yield- up its constituents slowly and apparently just according to 

 the requirements of the plant, a fact which makes this waste-material 

 very useful in horticultural cultivations, including the vine. The 



ential nature of lime as a food for the pine-apple will be evident. 

 from Mr. Bowrey's analysis. It is doubtless the more abundant pre- 

 sence of lime in the soils of Clarendon which gives an advantage to 

 the growers in that part. 



The cultivation of the pine-apple is a matter of much practical 

 interest ; it requires the constant attention of the cultivator, but the 



