GUANO. 



The total comparative produce in Ibs. of 

 potatoes from these manures was therefore 



Guano, or sea-fowl dung, at 35 bushels per acre - 639 



Horse dung, 35 cart loads per acre ... 626 



Hogs' dung, 35 cart loads per acre - - - 534 



Soil simple 446 



With mangel-wurzel the produce per acre 

 on a similar soil was as follows : 



Leaves. 



tons. 



Rootg. 



Soil simple ------ 38 19* 



Hogs's dung and ashes, 360 bushels per 



a e cre . . . '_ . . . 131 66* 



Guano, 35 bushels per acre - 153} 77} 



The guano, or sea-fowl dung, adds General 

 Beatson, which is found in considerable quan- 

 tities upon Egg Island, was first recommended 

 to my notice by Sir Joseph Banks, President 

 of the Royal Society. " It furnishes," says he, 

 "the loading of an immense number of ves- 

 sels that are constantly employed in bringing 

 it from small islands to the main land on the 

 western coast of South America, where it is 

 sold and distributed for the purpose of ma- 

 nure, for which it answers in a degree infi- 

 nitely superior to any other article we have 

 the knowledge of. A handful is considered as 

 sufficient for several square yards of land, the 

 produce of which is exuberant in consequence 

 of the force of this application." 



The accuracy of this valuable communica- 

 tion has been most amply confirmed by my 

 experiments in the culture of potatoes, as well 

 as upon grass lands. Thirty-five bushels of 

 the guano, or 3 cart-loads per acre appear to 

 me equivalent in effect to 70 loads of good rot- 

 ten dung. I should imagine that abundance 

 of this most valuable manure might be had 

 from many of the rocks and islands on the 

 coast of Scotland. The effect of the guano 

 upon grass lands is comparatively greater than 

 in the potato experiment. From what cause 

 this proceeds it may be difficult to explain ; 

 but as Dr. Priestley found, by experiment, that 

 vegetables throve best when they were made 

 to grow in air made putrid by the decomposi- 

 tion of animal and vegetable substances, it 

 may be inferred that the very strong effluvia 

 which issue from the sea-fowl dung or guano, 

 together with its being readily washed among 

 the roots of vegetables by the first falls of rain, 

 are circumstances that may possibly render its 

 effects as a top-dressing greatly superior to 

 those it produces when it is mixed with the 

 soil. On the 29th of July, 1808, 1 marked out 

 a space on the lawn in front of Plantation 

 House, which measured 1 rod in breadth and 

 12 rods in length; this was divided into 12 

 equal parts, or square rods, and numbered 

 progressively from 1 to 12. The guano was 

 reduced to a powder and sifted, and upon No. 

 1 a quart of this powder was evenly strewed 

 by the hand; this is at the rate of 5 Winches- 

 ter bushels per acre, because 160 square rods, 

 or an acre, would have required that number 

 of quarts, or exactly 5 bushels. In the same 

 manner No. 2 had 2 quarts, No. 3, 3 quarts, 

 and so on to No. 12, which had 12 quarts, or 

 at the rate of 60 bushels per acre. From the 

 29th of July there were daily drizzling rains 

 until the 5th of August, when the effect of this 

 invaluable manure began to appear. On the 



GUANO. 



following day the whole extent of the 12 rods 

 became highly verdant, and exhibited such a 

 contrast to the unmanured part of the lawn, 

 that it had the appearance of having been 

 newly turfed with a finer kind of sod. The 

 effect gradually increased, and in the first 

 week of October, that is, in a little more than 

 two months, the higher numbers, from 6 to 12, 

 having from 30 to 60 bushels per acre, excited 

 the surprise of every person who saw them, 

 being covered with the most. exuberant grass 

 that can be imagined, and having more the re- 

 semblance of a crop of young wheat very 

 thickly sown, than of any grass I ever beheld. 

 This is more remarkable, as at that time the co- 

 pious rains which fell in August and the spring 

 season had made no visible effect on the adjoin- 

 ing part of the lawn. It was from a frequent 

 and careful inspection of the above experi- 

 ments that I have estimated 35 bushels of gu- 

 ano per acre to be equivalent in effect upon 

 grass lands to seventy loads of well-rotted 

 dung. I have been informed that guano is 

 sold at Lima, and at other towns on the coast 

 of Peru, for a dollar a bag of 50 pounds weight, 

 and that it is much in use there for manuring 

 fruit trees and gardens. It is certainly one of 

 the most powerful of manures, and therefore it 

 is necessary to be cautious in using it. I have 

 observed, when too much is laid on grass, 

 that it burns and destroys it. I would, there- 

 fore, recommend to those who may try it on 

 fruit trees, to begin with not more than three- 

 quarters of a pint to each tree, and to trench it 

 about a foot deep all round the roots. If the 

 first application be found insufficient, a second 

 or third may be given at intervals of two or 

 three months; or a better mode, perhaps, of 

 determining the quantity of guano proper for 

 each fruit tree, would be to select about a 

 dozen trees of the same kind and size, and to 

 vary the quantities by an easy progression, 

 from three-quarters of a pint to one or two 

 quarts, or more, to each tree. (Com. Board of 

 dgr., vol. vii. p. 225 240. 



The price at present of guano in England 

 is 25*. per cwu, or JE12 per ton. As it costs 

 only about 3s. per cwt. at the South American 

 ports, near which it is obtained, it should be 

 imported and sold at a lower price. 



In any case, says J. F. W. Johnston, it seems 

 improbable that guano can continue to be im- 

 ported into England for any length of time. 

 It is absolutely necessary to the cultivation of 

 the land in Peru, and it is also diminishing 

 in quantity, the first settled government, there- 

 fore, which is formed in that country, must 

 prohibit the further exportation of a substance 

 so important to the national interests. It is a 

 matter not unworthy of the attention of che- 

 mists, therefore, to consider whether a mixture 

 similar to the guano, and of equal efficacy, 

 cannot be formed by art not only at a cost so 

 reasonable as at once to make the farmer 

 independent of the importer, but also in such 

 abundance as at the same time to place so 

 valuable a manure within the reach of all. 



Several attempts have been made to manu- 

 facture an artificial guano, and the results have 

 shown considerable success. 



The following mixture contains the various 



597 



