Dr Davy's Agricultural Discourse, 303 



kind derived from the soil, he will conclude, that with good 

 management, a cane-crop is not exhausting ; and that if the 

 leaves and stalks are returned to the soil, the land instead 

 of being impoverished, may be actually enriched, in as much 

 as there is given to the soil a vast accession of vegetable 

 matter, the elements of which have been obtained from the 

 atmosphere, and which, in decomposing, render up these ele- 

 ments to support the growing crop, being, as it were, to the 

 young plant what the milk of the mother is to the young ani- 

 mal. I should add, that the inquiry of the agricultural che- 

 mist will by no means be complete, unless his attention also 

 be directed to the soil, and that not only once, but at inter- 

 vals. If, on his first examination of it, he find a marked de- 

 ficiency in it of phosphate of lime, and of other inorganic sub- 

 stances which seem to be essential to the composition of the 

 sugar cane in its healthy state, he will suggest the use of 

 guano as a manure, or of bone-dust, or of marl containing 

 phosphate of lime, according to circumstances. If, after an 

 interval of a few years, the land having yielded good crops, 

 he examine the soil again, and now finds in it no marked de- 

 ficiency of phosphate or carbonate of lime, or other supposed 

 requisite inorganic ingredient, he will, I conceive, be war- 

 ranted in suggesting the sparing the expensive manures, the 

 guano and the bone-dust, and using only manure chiefly ve- 

 vetable, made on the estate. 



Such, I fancy, is the line of inquiry, as regards particular 

 manures, that is likely to be most useful, and the more use- 

 ful, I cannot but think it will be, the more minutely, and 

 carefully, and judiciously it is carried out, testing theoretical 

 suggestions founded on chemical analysis, by the results of 

 practical experince, that is, by well conducted trials, and ex- 

 tending them from point to point, till satisfactory knowledge 

 is arrived at, so that being acquainted with the quality of the 

 soil, the quality and quantity of manure applied, the mode of 

 tillage employed, the planter may be able to calculate, com- 

 munibus annis, what will be the quantity and quality of sugar, 

 what the quantity and quality of the molasses, and what the 

 quantity of rum, that should be made on his estate. 



The subject of manures is far too large a one for a single 



