64 MIXED MANURES, CONSIDERED 



steppes ; and, applied in small quantities, it appears to hasten the decompo- 

 sition of organised matter in the soil. As a manure, however, it requires to 

 be applied with very great caution ; and, in gardens, is perhaps safest when 

 used in walks for the purpose of killing weeds and worms. 



206. In suburban villas calcareous manures are often required for the im- 

 provement of lawns and other grass lands ; and a stock of quicklime, un- 

 slaked, should always be kept in a cask, or other closed vessel, to be ready 

 for use with water. Where lime is not at hand, common pptash or Ame- 

 rican pearlash dissolved in water, or urine especially that of cows, will have 

 the same effect on insects as lime-water ; but they are more expensive. 



SECT. III. Mixed Manures. 



Mixed Manures include coal ashes, vegetable ashes, street manure, soot, 

 and vegetable or vegeto-animal composts. 



207. Coal Ashes are of very different natures in different parts of the 

 country ; the constituents of coal varying in the quantity of clay and lime, 

 and also of sulphur and iron, which it contains. Many persons object en- 

 tirely to coal ashes as a manure, considering them poisonous rather than 

 beneficial. The portions of coal which contain iron or other metallic ores 

 are converted by burning into hard porous masses, which, when buried in 

 the soil, absorb moisture, and consequently soluble organic matter ; and as 

 the spongioles of the roots cannot be supposed to penetrate into cinders or 

 scoria, that soluble matter must remain there till it is washed out by rains or 

 set free by the disintegration of the cinder. Supposing this to be the case, 

 the principal benefit to be derived from coal ashes would appear to be that 

 of increasing the friability of stiff clayey soils. 



208. Vegetable Ashes are obtained by burning weeds, leaves, prunings, or 

 roots of woody plants, and in general of all kinds of vegetable matter not 

 readily decomposed by fermentation. The burning of vegetable substances 

 must necessarily dissipate the whole of the oxygen, hydrogen, and nitrogen 

 which they contain, together with more or less of the carbon, according to the 

 degree in which the burning mass is exposed to the action of the atmosphere, 

 Hence in burning wood for charcoal, the pile of logs is covered with earth 

 or mud to prevent the production of flame, and consequent decomposition 

 of the carbon, by the action of the oxygen of the atmosphere. The 

 burning of vegetables, however, does not destroy the fixed saline ingredients 

 which they contain ; and hence vegetable ashes, as manure, will be valuable 

 as containing salts which are either of general or specific use to plants, and 

 also as containing more or less carbon. If one kind of plant only were 

 burnt at a time, then the ashes of that plant would form a specific manure 

 for plants of the same kind ; but as a number of kinds are generally burned 

 together, their ashes must contain salts of various kinds, and they may be 

 considered as being useful to plants generally. Among these ashes there 

 is always a large proportion of vegetable alkali (carbonate of potass) ; and 

 this, when mixed with soil, combines with insoluble organic matter and ren- 

 ders it soluble ; and hence vegetable ashes form a useful manure for all soils, 

 since potass is of almost universal existence in plants. It is therefore not 

 only a general manure by its action on organic matter, but a specific con- 

 stituent of plants. Soda, which exists but in few plants, differs from potass 

 in not being a specific manure, its action being limited to increasing the 



