14 ORGANIC MANURES, CONSIDERED 



essential, not only for growing many of the Cape and Australian shrubs, 

 but also for general use. 



Fresh and tender vegetables dug into the soil, produce an immediate 

 effect, from the facility with which they undergo fermentation, and 

 thus supply soluble matter for the spongioles. Sea-weed is still more 

 readily decomposed than recent land or garden plants, in consequence 

 of the mineral alkali which it contains ; and hence this manure is 

 stimulating as well as enriching. Malt-dust is valuable for the sac- 

 charine matter which it contains, and rape-cake for its albumen and 

 oil ; but these manures are only occasionally to be met with. Straw, 

 haulm, and in general all the stems and leaves of herbaceous plants, 

 and the shoots, with their leaves on, of trees and shrubs, form valuable 

 manure when decayed ; more especially if, from the saccharine matter 

 which they contain, or the addition of stable manure or of animal 

 matter, they can be made to heat and promote fermentation. Never- 

 theless, without fermentation, they form useful garden manures, or 

 moulds, which, like leaf-mould, may often be substituted for heath- 

 soil. 



The least valuable truly vegetable manure is spent tanner's bark, 

 which, consisting entirely of woody fibre impregnated with tannin, not 

 only contains no soluble matter, but the tannin, in as far as it can be 

 taken up by the spongioles, seems to prove injurious. Nevertheless, 

 even spent tanner's bark may be rendered fertile, by mixing it with 

 sand, clay, lime, or some other earthy substance which will supply the 

 plants grown in it with the necessary salts, and also keep its particles 

 sufficiently open to admit the air. From the porosity and lightness of 

 tanner's bark, it is an excellent non-conductor of heat ; and hence, 

 when laid on the surface of the ground as a covering to the roots of 

 tender plants, it protects them better from the frost than a more com- 

 pact covering, such as coarse sand, or than coverings which are great 

 absorbents of moisture, such as leaves or half-rotten litter, or any other 

 covering of this kind which does not act as thatch. Rotten tan, how- 

 ever, being peculiarly favourable to the growth of fungi, should be used 

 with great caution when applied about young trees, and more es- 

 pecially Coniferae. 



Peat soil is of two kinds, that formed in peat bogs by the growth of 

 mosses, and that found in valleys, or other low tracts of country, which, 

 being formed of overthrown and buried forests, consists of decayed 

 wood. The latter being the remains of a much higher class of plants 

 than the former, must contain a greater variety of the constituent 

 elements of plants, and must consequently be a better manure. Peat 

 from bogs cannot be used till it has been reduced, either by time or 

 fermentation, to a fine mould or a saponaceous mass ; the former result 

 is obtained by exposure to the air, and repeated turnings during 

 several years, and the latter by fermentation with stable dung. A load 

 of this material, mixed with two loads of partially dried peat, will 

 commence the putrefactive process, in the same manner as yeast com- 

 mences fermentation in dough ; and, in the one case as in the other, 

 additions of any quantity may be made by degrees, so that two loads 



