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To the sugar-planter the question of soils and manures is doubtless 

 becoming more important every day, and any practical observations 

 upon a subject which affects to so great an extent the future prosperity 

 of our West Indian Colonies cannot fail, I believe, to have a certain de- 

 gree of interest at the present time. 



II. 



It is not very long ago since the great chemist, Justus von Liebig, 

 showed that by burning a plant and analysing the ash we not only 

 learnt what that plant derived from the soil, but the food necessary to 

 render it luxuriant in a given soil. However, when Liebig asserted 

 that the mineral ingredients found in plants were its only true and 

 natural food, Professor Boussingault, who, with Dr. Mulder and Sir TL 

 Davy, must be looked upon as oDe of the fathers of Agricultural 

 Chemistry, simply refuted the theory by applying the ashes of farm- 

 yard manure and an equivalent of farmyard manure itself, side by side, 

 upon the land. The latter gave luxuriant crop ; the former produced 

 nothing. In fact, I have convinced myself that the burning of a vegetable 

 to procure the ash renders the mineral food it naturally contains almost 

 useless as manure. 



More recently the laborious experiments of Lawes and Gilbert 

 have weakened the faith of agriculturists in mineral manures, 

 though Lawes himself has long been a manufacturer of them, and 

 at the outset of his agricultural researches took out a patent for mak- 

 ing superphosphate. The results obtained by these gentlemen have 

 not overthroicn the fact originally proclaimed by Liebig, that the mineral 

 substances found in the soil and in the crops are of the greatest im- 

 portance to the agriculturist ; they have merely shown once more that 

 nitrogen is likewise necessary, and after some twenty years of experi- 

 ments have arrived at the conclusion that the largest crops ivere obtained 

 when the mineral and nitrogenous manures were employed together. 



This applies more particularly to the wheat plant, which belongs, 

 however, to the same family as the sugar-cane. Both are plants of the 

 grass tribe ; but the one is cultivated for the seed, and the other for its 

 saccharine juice. Turnips, on the other hand, are grown principally 

 for the roots, and it has been found by direct experiments that on most 

 soils acid superphosphate is a very advantageous manure for this crop. 

 But should we send out turnip manure for the sugar-cane ? I think 

 not. Direct experiments, extending over a long series of years, have 

 shown that on the average soils superphosphate alone does little or no 

 good to wheat ; how can we expect that it will affect the sugar cane ? 

 It contains a large amount of free acid, which the cane cannot touch 

 until it is neutralised by the lime or potash of the soil ; and long- worked 

 cane soils are for the most part already much too acid. 



Sulphate of ammonia, largely employed in Demerara and elsewhere, 

 acts as a powerful stimulant upon all graminaceous plants growing on 

 average qualities of soil. With regard to the sugarcane, its immediate 

 effect is the rapid rise of the green cane, and often the production of a 

 watery juice, poor in sugar. It is moreover a highly exhaustive 

 manure, causing the plant to take up lime, potash, and phosphoric acid 

 from soils well-nigh worked out, and giving, for the time, the appearance 

 of extraordinary fertility. 



