VALUE OF MANURES. 215 



contrary action of the manure on tlie two soils, by stating- 

 that the meadow at Trewithen, having* been highly manured, 

 for the last seven years with farm-yard dung, might be 

 considered as fairly rich in carbonized and nitrogenized 

 matter, besides a tolerable amount of alkaline ])hosphates 

 and silicates ; but the Carnwinick soil could not atlbrd much 

 of these matters; for, excepting the ashes left from the 

 burning of the furze root, Sec, there was probably very little 

 else, saving the inorganic or mineral elements which the 

 soil itself atforded. He knew nothing of the composition of 

 Professor Liebig's manure ; he believed it to be entirely a 

 mineral one ; but the next experiment would perhaps throw 

 some light on the subject of its failure at Carnwinick. This 

 was made on a very extensive scale by J. D. Gilbert, Esq., 

 Trelissick, on a wheaten arish of 10 acres, lying on coarse 

 argillaceous slate, abounding in quartz (provincially spar- 

 stones), the soil of which was extremely poor, having been 

 very considerably injured by bad farming previous to its 

 coming into Mr. Gilbert's possession. It was valued at 12.?. 

 per acre ; and in preparing the land for a turnip crop of 

 " Scotch yellows," it was ploughed 7 inches deep, and the 

 seed and manure drilled in 27 inches apart. 



No. Manure per acre. Cost. Produce. 



1.— Bone-dust 72*... 10 tons. 



2. — Fish refuse ' (one load of fish offal with 1 1 loads 



ofeartW — .. l]i 



3.— Farm-yard dung 100 .. IQi 



4. — 3 cwt. of Liebig's patent manure 35 . . 6 



5.-3 cwt. ditto, with 200 lb. of Ichaboe guano .... 59 . . ll-\ 



6. — 100 lb. of Ichaboe guano 32 . . 13 



7. — 24 bushels of bone-dust and 100 lb. of nitrate 



Qfsoda 91 .. 20^ 



8. — 24 bushels of bones and 100 lb. of nitrate of 



potash 98 . . 20| 



The produce in each case, excepting the two last, was ex- 

 ceedingly light, but the experiment is an interesting one, as 

 testing the efiect of eight different manures on a poor ex- 

 hausted soil. In this instance Liebig's manure, compared 

 with the guano, No. 6, at about the same cost per acre, 

 yielded only two-fifths of the weight of turnips; and in the 

 trial No. 5, where 200 lb. of Ichaboe guano were added to 

 Liebig's manure, the weight of turnips compared with No. 4, 



' The recent fish refuse, according to a note in the last edition of Sir 

 H. Davy's work on Agricultural Chemistry, contains about four per cent, 

 of nitrogen, besides the phosphates. 



