ORGANIC MANURES. 



293 



ever, for damp soils than for light and sandy 

 ones. Applied as manure, it has been found 

 destructive to that intolerable pest the wire- 

 worm (cide p. 182). The rate at which it is ap- 

 plied is about 5 cwt. per acre. 



Leaves of trees. — These, from necessity, are col- 

 lected during autumn and winter in large quan- 

 tities where extensive pleasure-grounds exist, 

 and, when rotted down, afford an excellent ma- 

 nure for most soils. Leaves of trees, when de- 

 cayed, as well as the wood itself when so reduced, 

 form what is termed vegetable mould, containing 

 more charcoal but less oxygen, weight for weight, 

 than the plants that produced it. It yields more 

 ammonia, and contains more azote, on account of 

 the different circumstances under which it has 

 been formed. Vegetable mould is an indispen- 

 sable manure in garden culture. 



Tanners' bark — Both bark and leaves of trees, 

 according to Donaldson (in " Treatise on Soils 

 and Manures," p. 15), "require long time, and 

 much mixing and preparation, to reduce them 

 to mould : hot lime will be the quickest solvent 

 for fresh bark, and the destruction of the fibre 

 being effected, earths and dung may be added, 

 which will bring the whole mass into a soluble 

 and putrescent state. Hot stable-dung has been 

 used in the first application, in order to reduce 

 the woody fibre ; but caustic lime is stronger 

 and quicker, and, after the dissolution has been 

 effected, the mild, materials may be added, and 

 the mixture completed. Time will effect a dis- 

 solution of the fibre without any mixture with 

 the bark ; but a long period will elapse, and it 

 is usually preferred to break it up by hot appli- 

 cations. The reduced mixture may be used as 

 a manure for any purpose, but chiefly for top- 

 dressings, arising from its finely divided and 

 comminuted state." With decayed leaves and 

 a copious admixture of sharp sand, it makes an 

 excellent compost for growing American plants 

 in, many of which, particularly azaleas and rhodo- 

 dendrons, thrive as well in it as in natural peat- 

 earth. It is a good manure to light sandy soils 

 deficient in vegetable matter, and, in a less de- 

 composed state, valuable for keeping open soils 

 of the closest texture. 



Sawdust is much of the nature of tanners' 

 bark ; but, unless entirely of oak wood, it con- 

 tains much less of the tannin principle, that 

 of coniferous trees containing a considerable 

 amount of resinous matter ; but when both are 

 extracted, it forms with sand a good substitute 

 for peat, for hardy shrubs and trees. Both, 

 however, should be broken down without the 

 use of caustic lime, when intended for such pur- 

 poses, as all American plants have a dislike to 

 calcareous matter even in small quantities. 

 Both tanners' bark and sawdust, when charred, 

 constitute a tolerable manure, and are both in 

 that state valuable^ when incorporated with 

 nightsoil, urine, and similar potent manures. 



Boms and hoofs of animals are similar in con- 

 stitution, containing very little earthy matter, 

 and only 0.023 of phosphate of lime ; the chips 

 and shavings of both, procured of the comb- 

 makers and turners, have been strongly recom- 

 mended by some. Repeated trials have not led 

 us to a like conclusion. 

 VOL. II. 



Oyster shells, like those of both sea and fresh- 

 water animals, are constituted chiefly of carbon- 

 ate of lime combined with soft animal matter ; 

 they differ chiefly from animal bones in having a 

 much greater proportion of carbonate of lime, af- 

 fording sometimes almost pure lime when burned. 



Bones ground to powder are extensively used 

 in stimulating the first efforts of vegetable life, 

 being sown immediately before, or along with, 

 the seed. In a crushed state they are employed 

 in the formation of vine borders, as they are 

 slow in decomposing, and, in their decay, afford 

 food to the plants long after all other manures 

 applied at the same time have become exhausted. 

 We have found them excellent as drainage for 

 plants intended to be kept long in the same pot. 

 The action of bone-dust upon the soil appears to 

 be little understood. " Up to a certain quan- 

 tity used," Mr Stephens remarks, " this manure 

 has an evidently beneficial effect, but beyond 

 that quantity no apparent benefit is derived 

 from its use, in so far, at least, as the crop is 

 concerned. I have tried to raise turnips," he 

 says, " with different quantities of bone-dust, 

 varying from 12, 16, 20, to 24 bushels per acre, 

 and found the crop improved up to 16 bushels ; 

 but the quantities beyond that, even to 24 

 bushels, produced no greater effect on the crop 

 in the same field, and on the same sort of soil, 

 than 16 bushels. It is therefore unnecessary," 

 he concludes, " in so far as the crop of turnips 

 is concerned" (that being the crop he experi- 

 mented upon), " to sow more than 16 bushels of 

 bone-dust alone, or 8 bushels with coal-ashes or 

 street manure." Where the ground has been 

 previously manured with farmyard dung, 8 

 bushels of bone-dust is deemed amply sufficient 

 for any annual crop. Bone-dust, in combina- 

 tion with sulphuric acid, has of late years been 

 greatly recommended, and in this state it has 

 been found to have greater effect in raising 

 crops on strong land than bone-dust alone. The 

 manner of preparing the sulphurated bones is 

 to mix a given quantity of sulphuric acid with 

 twice its bulk of water, and to place twice the 

 weight of bone-dust as of the acid in a tub or 

 trough, and pour over the bones the prepared 

 liquid gradually, and by times ; the bones will 

 become entirely dissolved, and form a mass with 

 the acid and water. When the mass is dried, 

 it will assume the appearance of granulated pow- 

 der, and is then fit for use. One cwt. of bones, with 

 56 lb. of sulphuric acid, will be sufficient bone- 

 manure for an acre of strong garden-ground, 

 previously manured with stable-dung ; for it 

 should never be overlooked that bone-dust, like 

 most others of the modern fertilisers, should 

 only be regarded as an auxiliary, and not as a 

 general manure. Bones are often broken down 

 by fermentation with sifted coal-ashes, and even 

 with pure sand, and their value considerably 

 increased, probably on account of their being 

 disintegrated to the smallest possible degree, 

 and thereby mixing more readily with the soil. 

 The method of fermenting bone-dust in this 

 manner is thus described by Mr Stephens : " Mix 

 four cart-loads of bones with as many of sand, 

 or mould, or sawdust, in a flat-topped heap. 

 The bones should be thoroughly drenched with 



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