51 



We know also that cane trash is burnt and the ash restored carefully 

 to the soil in almost all the West India Islands and Demerara. 

 Unfortunately for the cause of the sugar-planter, this cane trash is used 

 there as fuel, and we cannot expect to get work twice out of the same 

 material. If it were fermented in a moist heap like stable manure, it 

 would yield its fertilising elements to the soil and the plant ; but 

 when burnt its nitrogen is gone, its silica and lime have become almost 

 completely insoluble and unavailable, and it can only supply directly a 

 certain moderate amount of potash. But cane soils lose their lime 

 long before their potash is all gone. 



Add to the substances already named Peruvian guano — not only a 

 very costly manure, but one which, injudiciously applied, is very apt to 

 endanger a crop of sugar — and we have nearly all the auxiliaries to labour 

 which, until recently, the sugar- grower has had at his disposal, and has 

 employed in many cases without sufficient knowledge of the require- 

 ments either of the cane or the soils in which it is planted. 



III. 



Let us now proceed to glance at the requirements of the sugar-cane, 

 and those of the long-cultivated soils of our Colonies ; the differences 

 presented by the soils of new and old plantations ; the manures best 

 suited to restore the soil of partially-exhausted estates, and to ensure 

 the largest yield of sugar in the stiff clays of Demerara, Barbadoes, 

 Jamaica, &c. 



The composition of the fully-developed sugar-cane may be very fairly 

 represented by the following good average analysis : — 



Sugar Cane. 



Water ... ... 71.04 



Sugar ... ... 18.02 



Cellulose ... ... 9.56 



Albumine ... ... 0.55 



Fatty and colouring matters ... 0.35 



Salts soluble in water ... 0. 12 



" insoluble " ... 0.16 



Silica ... ... 0.20 



100.00 



So that a thousand tons' weight of cane takes up from the soil a little 

 more than four tons of mineral ingredients, and if the soil cannot 

 supply these four tons in the proper form — i. e., capable of being 

 assimilated — no crop of sugar can be raised. About one ton of nitrogen 

 is required to form the albuminous matter of one thousand tons of 

 cane. 



The next question that presents itself is, What are the nature and 

 relative proportions of these mineral ingredients derived froni the soil ? 

 This is obtained by careful analysis of the ash of the full-grown cane 

 and its leaves. There exists great discrepancy in the various analyses 

 of cane ash that have hitherto been made, the cause of which I shall 



