Recent Publications on Manures. 83 



Mark Lane Express, says, 4 bushels of guano (52 lb. per bushel) 

 to the acre, mixed with 1 bushel of charcoal powder and drilled, 

 produced 6 quarters, 2 bushels, ] g pecks per acre of wheat ; 

 when 15 bushels of bone dust yielded only 4^ quarters. Mr. 

 Cuthbert Johnson says that, in St. Helena, 35 bushels of guano 

 are said to produce more potatoes than 35 loads of horse dung. 

 Three cart-loads of guano, he says, are equal to 70 loads of 

 good rotten dung, and its effects are greater on grass than on po- 

 tatoes. From all accounts, guano appears to be a powerful 

 concentrated manure ; and the ammonia in it does not seem 

 to be so volatile as dreaded by some chemical writers. 



Blubber of fish and oil, Mr. Squarey says, " yield 70 per 

 cent of carbon, on which their benefit depends ; and he proposes 

 to mix these substances with coal ashes and apatite, to absorb 

 them and give them off to the roots as wanted." Coal ashes he 

 thinks valuable, from their yielding sulphate of lime and char- 

 coal : the principal benefits however arise, he thinks, from the 

 absorbing powers of charcoal for ammonia, which is washed 

 out by rain for the roots of plants, and a new quantity again 

 absorbed. The effect is much diminished, he says, "by reducing 

 the coal ashes to powder, as they do not absorb so well." As 

 I stated before, however, practice has led me to adopt a dif- 

 ferent opinion : I have often seen the bad effects of mixing 

 coal ashes from domestic fires, especially when not well sifted, 

 and the pieces large ; they absorb the juices of the dung, reducing 

 it to a dry straw, and I never could see the ashes produce any 

 corresponding effect in consequence of it. The fact of the 

 matter, I believe, is, that when the pieces are large, the ordinary 

 moisture of the soil will not penetrate them so as to extract 

 what is absorbed. When the pieces are small, and when the 

 ashes are reduced as small as possible by sifting and burning 

 well, they are found much more beneficial ; and all persons whom 

 I have ever conversed with, who are in the habit of purchasing 

 such manures to a great extent, universally prefer the small 

 powder of well burned, well sifted ashes, to the coarse un- 

 sifted kind. The small pieces absorb and give off, the same as 

 the particles of soil do ; and, falling into powder, their saline 

 substances and charcoal are in a more soluble and available state. 

 Of what great benefit are absorbents to the soil, when every 

 particle of the soil itself is capable of absorbing, and, by its 

 disintegrating readily, yielding up its absorbed substances easily. 

 The object is not to absorb and lay up manures, it is to make 

 them as speedily available as possible. Of the great tenacity 

 with which some of these absorbents retain the ammonia they 

 absorb, we have a familiar instance in iron. When a large pot 

 of cast iron has been exposed for a long time to the action of 

 the air, it absorbs ammonia to such a degree, that, though cold 



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