MAN 



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MAN 



from the atmosphere ; thirdly, by ab- 

 sorbing the gases of the atmosphere; 

 fourthly, by stimulating the vascular 

 system of the plants. Manures approxi- 

 mately assist vegetation, first, by kill- 

 ing predatory vermin and weeds ; se- 

 condly, by promoting the decomposition 

 of stubborn organic remains in the soil ; 

 thirdly, by protecting incumbent plants 

 from violent changes of temperature. 



All these properties seldom if ever 

 occur in one species of manure, but 

 each is usually particularized by pos- 

 sessing one or more in a superior de- 

 gree. That is the most generally appli- 

 cable manure, which is composed of 

 matters essential to the growth of plants: 

 the chief of these are carbon, hydrogen, 

 and oxygen; therefore all animal and 

 vegetable substances are excellent ma- 

 nures. It would evidently be of great 

 benefit, if every plant could be manured 

 with the decaying parts of its own spe- 

 cies; tiie ancients made this a particular 

 object. We read that those vines were 

 the most fruitful, which were manured 

 with their own leaves and prunings, and 

 the skins of expressed grapes. This 

 rule might be so far followed, as that 

 the stems of potatoes, peas, &c., could 

 be dug respectively into the compart- 

 ments where those crops are intended 

 to be grown in the following year. 



Of the less general manures which 

 benefit plants by entering into their 

 composition, a few words will suftice. 

 Sulphate of lime (gypsum) is a compo- 

 nent of clover, lucerne, turnips, &c.; 

 hence it has been applied with benefit 

 to these crops on such soils as did not 

 already contain it. Bones broken small 

 have lately become a very general ma- 

 nure; their utility is easily accounted 

 for. The bones of oxen contain about 

 fifty per cent, of gelatine, which is 

 soluble in water, and rapidly becomes 

 putrescent. The remainder is chiefly 

 phosphate and carbonate of lime, salts 

 which are components of wheat, rve, 

 barley, oats, peas, beans, vines, cucum- 

 bers, potatoes, garlic, onions, truffles, 

 &c. 



Common salt also is employed as a 

 manure, and is beneficial, partly in con- 

 sequence of entering into the constitu- 

 tion of plants. 



Some manures ameliorate a soil by 

 absorbing moisture from theatmosphere. 

 This property is at least as beneficial to 

 ground that is aluminous as to that 



which is siliceous; for it is equally use- 

 less to either during such periods of the 

 year as are characterized by a plentiful 

 deposition of rain; but in the drought 

 of summer, when moisture is much 

 wanting to plants, it is beneficial to 

 both; in very dry seasons it is even 

 of greater importance to clayey than 

 to light soils ; for vegetation on the 

 former suffers more from long continued 

 drought than on the latter, inasmuch as 

 that moisture being equally exhaled 

 from each, the surface of the clayey 

 soil becomes caked and impervious to 

 air, the only grand source of compensa- 

 tory moisture that is available to the 

 languishing plants, and which is more 

 open to those which grow on light, and, 

 consequently, more pervious soils. 



The following table of the compara- 

 tive absorbent powers of many manures, 

 is extracted chiefly from An Essay on 

 the Use of Salt in Agriculture, by Mr. 

 Cuthbert Johnson. 



Parts. 

 Horse-dung evaporated pre-^ 

 viously to dryness, at a | 

 temperature of 100^, ab- 1 

 sorbed during an exposure f" 

 of three hours to air satu- \ 

 rated with moisture at 62'^ J 

 Putrefied tanners' bark,~ 

 under similar circum- 

 stances (66') .... 

 Unputrefied tanners' bark 



Cowdung 130 



Pig dung 120 



Sheep dung 81 



Pigeon dung oO 



Refuse marine salt (GC^) . . 49i 



. Soot (68°) 36 



Burnt clay 29 



The richest soil (in one hour) 23 



Coal ashes 14 



Lime (part carbonate) . . 11 

 Crushed rock salt .... 10 



Gypsum 9 



Ciialk 4 



The absorbing power of a manure is 

 much influenced by the state in which 

 it is presented to the atmosphere, lii 

 a finely divided state mere capillary at- 

 traction assists it; hence, the import- 

 ance of keeping the soil frequently 

 stirred by hoeing, &c. But a mere 

 mass of cotton, by means of capillary 

 attraction, will absorb moisture from the 

 air, yet it parts with it at a very slight 

 elevation of temperature : it is of im- 

 portance therefore to ascertain whiuli 



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