THE FARMER'S MAGAZINE. 



115 



COMMERCIAL AND AGRICULTURAL VALUE OF CERTAIN PHOSPHATIC ROCKS 

 OF THE ANGUILLA ISLES, IN THE LEEWARD ISLANDS. 



Sir, — A few weeks ago I perceived in your journal a com- 

 munication from Sir Roderick Impey Murchiaon, V.P.R.S., to 

 the Journal of the Royal Agricultural Society of England, 

 respecting the commercial and agricultural value of certain 

 phosphatic rocks of the Anguilla Tales in the Leeward Islands: 

 conveying information which cannot be made too generally 

 known, nor too highly appreciated, either in a commercial or 

 national point of view. For no sooner had the researches in 

 organic chemistry during the last twenty years explained the 

 elaborations of vegetable economy, and reduced agricultural 

 operations comparatively to defluite laws, by defining the 

 nature and determining the relative proportions of these ele- 

 mentary and compound bodies ever present and indispensable 

 to the mature development of whatever crop it is the object 

 of the farmer to cultivate, than arose the question, From 

 whence was an adequate supply of those indispensable inor- 

 ganic constituents to be derived ? For, notwithstanding 

 there are many subjects connected with the daily operations 

 of the farm j^et to be discussed, it is generally admitted by all 

 acquainted with the great achievements in modern agriculture, 

 that wherever a commensurate amount of capital and science 

 are brought into operation iu this important field of national 

 industry, few investments are calculated to ensure more cer- 

 tain and remunerative returns; and none conferring more per- 

 manent good upon the country at large, as it directs the 

 energies and enterprise of a vast portion of the community to 

 be expended in a cause which must inevitably expedite the 

 general development of our agricultural resources, and aug- 

 ment to an indefinite extent the annual produce of the soil. 

 Now to render the present refined state of chemical analysis 

 subservient to the daily operations of practical husbandry, it is 

 not only essentially necessary that the farmer should know 

 the nature of the mineral and saline ingredients extracted 

 from the soil by the crops raised, but that he should have the 

 means of restoring to the land any of those ingredients indis- 

 pensable to the proper development of a crop of which it may 

 be deficient. For example, I need only remark that either 

 roots or cereals will vegetate with considerable luxuriance up 

 to a certain period of their growth, during which time they 

 had expended their sustenance iu the formation of cellular 

 tissue ; and for want of alkaline and earthy phosphates, and 

 azotized matter, the plants cannot attain proper maturity, and 

 we obtain bulk with little nutritious virtue. 



To enable the practical farmer to fully comprehend the im- 

 portant mission assigned to inorganic matter in the economy 

 of vegetable physiology, it is only necessary to estimate the 

 quantity of theae substances removed from the soil by a ton 

 of each of the following grasses ; — 



From the above statement it appears that the mineral and 

 saline ingredients extracted from the soil by the different 

 grasses cited coni^ists, iu the aggregate, of alkaline aud earthy 



phosphates, but assimilated in very different proportions by 

 the respective plants named. 



Thus we find, by contrasting lucerne with rye-grass, that the 

 former extracts from the soil close upon 380 per cent, more of 

 these materials than the latter, showing that one species of 

 grass may be cultivated with advantage upon a soil totally 

 incompetent to produce the other, without the agriculturist 

 can avail himself of the means to correct the defect. And the 

 history of all ancient states establishes the fact, that no sys- 

 tem of culture can compensate for the inordinate quantities of 

 these valuable substances removed from the soil iu remote 

 parts of the country in the form of milk, corn, cattle, or any 

 other form the produce may assume, without we return quan- 

 tities equivalent to those removed. As soon as the great fer- 

 tilizing power of phosphatic compounds was known, the at- 

 tention of many of the leading scientific men of the day was 

 directed towards discovering a source from whence a perma- 

 nent supply could be had. And at that time it was currently 

 reported that a considerable deposit of phosphate of lime 

 existed in the Spanish province of Estremadura; but after a 

 personal survey of the deposit by Dr. Daubeuy, it was found 

 unavailable to the purposes of British agriculture, chiefly 

 arising from the expense of transport. 



Indeed, various and extensive explorations have been made 

 by many eminent professional and scientific gentlemen 

 throughout the entire range of the cretaceous series of strata; 

 and although many of these deposits contained phosphoric 

 acid, except the phosphatic fossils of Suffolk and Essex dis- 

 covered by Professor Henslow, and now extensively used as a 

 substitute for bones in the manufacture of superphosphate of 

 lime, little was effected to promote the interest of agriculture. 

 And however much an adequate supply of mineral manure was 

 felt at that time, its value in agricultural operations has very 

 much increased since the passing of the Cora Law, inasmuch 

 as the farmer has been compelled, from the low price of grain, 

 to turn his attention more to grazing. And if attention is 

 directed to the rearing and fattening of cattle and sheep, an 

 adequate supply of earthy and alkaline phosphates becomes 

 more imperative, as they enter largely into the structure of 

 all animals, and necessarily forms the most valuable portion of 

 the food they consume. For instance, phosphate of lime 

 forms from 50 to 60 per cent, of all the bone reared and ex- 

 ported from the farm ; and the alkaline phosphates constitute 

 from 70 to 75 per ceut. of the ashes of both flesh and blood, 

 also forming about 80 per cent, of the ashes of the most 

 valuable food for cattle and sheep. 



After chemistry had elicited the important part assigned to 

 these phosphatic compounds in both animal and vegetable life, 

 it will be admitted that a plentiful supply of those ingredients 

 is of the greatest importance to practical agriculture. And 

 it is with that view that I now point out the Island of Som- 

 brero as the means of supplying these necessary requirements 

 of the day. 



The Island of Sombrero was visited so early as 1814 by an 

 English gentleman, and again about 1825, on which occasion a 

 report was made to the British Government ; but it was not 

 until 1856 that the Americans discovered this extraordinary 

 deposit of phosphatic guano, and at once took possession of 

 the island. And since that time large quantities have been 

 imported into the Southern States to replenish the exhausted 

 tobacco and cotton fields, and which has been attended with 

 surprising effect. 



Since Sir R. I. Murchison's communication appeared ia 

 your journal, I have had an opportunity of examining a cargo 

 of a thousand tons discharged in the port of London, ex 

 " Rochembean," from which the accompanying specimens are 

 selected, and are equally rich in phosphatic compounds as 

 those which Sir Roderick had analyzed from the same island, 

 varying from 75 to 90 per cent., according to the nature and 



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