22S agricultural report. [T435, 436, 437, 438, 439 



stable manure. Among artificial mixtures intended as universal manures, the 

 one known as "Mapes' Nitrogenized Superphosphate of Lime " has acquired 

 some reputation ; and new compositions ot a similar character are daily coming 

 forward. 



The superphosphate of lime, as also hone-dust, is a specific manure for the 

 maintenance of pastures, inasmuch as the largest part of the ingredients with- 

 drawn from them by the stock is thus replaced. It is also specially recom- 

 mended as a top-dressing for the turnip crop. 



435. Chilian Saltpetre; Common Salt. — Among the stimulants which may 

 sometimes be used with advantage, both by themselves and in addition to stable 

 manure or to the compost pile, we may mention Qmmon Salt, and Chilian 

 Saltpetre or nitrate of soda. There are, probably, but few cases in wheh the 

 action of either of these substances can be attributed to the ingredients they sup- 

 ply diredly; they act as solvents and decomposing agents, scmewhat in the 

 manner of ammoniacal salts, and the farmer ought to understand distinctly, that 

 large crops resulting frcm the use of these substances, have been produced 

 entiiely at the expense of his soil. Both salts, being but slightly absorbed by 

 the soil, are scon removed fnm it, to a great extent, by thediain waters (1J378). 



436. Plaster of Paris, or Gypsum, which is brought into ccmmeice for agri- 

 cultural purposes, under the title of "Land Plaster," occupies a prominent place 

 among stimulant manures. Its constituents — Lime and Sulphuric Acid — are 

 themselves important nutritive ingredients, as before stated. Yet its supplying 

 these ingredients to the soil is but rarely the main cause of its favorable effect 

 upon crops. While exposed to the atmosphere in a moist soil, it undergoes a 

 chemical change, caused by the ammonia and carbonic acid contained in the 

 atmosphere, both of which it attracts and fixes in the soil, the result of the pro- 

 cess being the formation of carbonate of lime and sulphate of on>mcnia. Loth 

 these substances are powerful stimulants, as has been explained above; and it 

 is they, and not the sulphate of lime originally applied to the soil, which often 

 produce the decided effects noticed after the application of this substance. Com- 

 bining as it does, the action of two important and powerful agents, one of which 

 is obtained gratis, as it were, from the atmosphere, it is used with great advan- 

 tage on clay or loam soils, not naturally strong, which have been temporarily 

 exhausted by severe cropping; serving very effectually the same purpose as 

 fallowing, besides enriching the soil by the ingredients it supplies. It is known, 

 however, to be ineffectual, and sometimes injurious, on acid soils (1J406) — for 

 reasons not perfectly understood. It is a special manure for clover, peas and 

 leguminous plants generally. 



437. Quicklime and Carbonate of Lime. — I have repeatedly mentioned the 

 mode of action of lime (^[308, ff.); I now resume the subject in connection with 

 some general remarks on the use of the calcareous marls of the State. I pre- 

 mise that in this respect, the only ditierence between the action of burnt and 

 unburt lime (the latter being the carbonate, or combination of the former with 

 carbonic acid), consists in the greater rapidity and energy of action in case of 

 the former as compared with the latter. Hence, a small amount of burnt 

 lime (provided it has not been allowed to became air-slaked (1J310), will, when 

 properly diffused through the soil, exercise the same effect as a much larger 

 quantity of unburnt, or air-slaked lime. — The process of air-slaking consists 

 in a resumption of water and carbonic acid from the air by the lime ; and is 

 therefore the reverse of burning, in which process the same acid is expelled. 



438 Action of Lime. — I have already sufficiently alluded to the action of 

 lime as a stimulant of the soil, by rendering available to plants ingredients 

 heretofore inaccessible to them. Its office as an indispensable article of food to 

 vegetables has also been mentioned (^368, ff). There are, however, several 

 other important purposes it may be made to serve, according to the necessities 

 of the soil ; the chief among which are the following : 



439. Firttly : It will correct the acidity of soils, which is usually the conse- 



