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tion of organic matter, and for this reason a soil poor in humus should 

 receive more sparing applications of lime than soils of a peaty 

 nature, or rich in organic matter ; it sweetens sour soils in neutral- 

 ising the acids; it decomposes injurious substances in the soil 

 (ferrous oxide, a plant poison, into ferric oxide, a plant food) ; it 

 promotes the process of nitrification by encouraging the presence of 

 special micro-organisms ; it increases the fertility of the soil by 

 helping some of the chemical processes which result in the more ready 

 absorption by the soil of phosphoric acid, potash, and ammonia. 

 Clay soils which show a tendency to "puddle" and form clods 

 when improperly tilled, are greatly improved by a dressing of lime. 

 This substance possesses 'the property of flocculating or coagulating 

 the clay particles, thus opening the pores of such soils and making 

 them less retentive of water and more permeable to air. 



Quick or caustic lime, which results from the burning of lime- 

 stone or carbonate of lime, is, chemically speaking, carbon oxide 

 (CaO). It acts more energetically than carbonate of lime, or mild 

 lime, and should be preferred for soils rich in organic matter and 

 on sour soils. 



Oyster shells and marble give the purest lime. Our coastal 

 limestone is not so good, and contains from 6 to 20 per cent, of 

 sand. When exposed to the air, or when moistened, quick lime 

 absorbs carbonic acid gas, and reverts to carbonate of lime (CaCO 3 ), 

 becoming slaked lime. During this process it increases considerably 

 in volume, and falls to powder. A bushel of good stone lime weighs, 

 when quick, 901bs. ; when slaked, it will measure nearly three 

 bushels ; each of which will weigh about 451bs. A bushel of 

 unslaked oyster shell lime weighs 601bs. When slaked it will 

 measure something over two bushels, each of which will weigh 401bs. 



The quantity of lime to use at one application depends on the 

 amount of vegetable matter the soil contains. Thirty bushels of 

 lime (12cwt.) is a safe application if the soil is quite thin and 

 contains but little vegetable mould. Several small applications of 

 lime are safer than one heavy one. Gas lime is another fairly cheap 

 source of agricultural lime. It rarely, however, contains more 

 than 40 per cent, of lime, the rest being made up of moisture and 

 compounds of sulphur or sulphites and sulphocyanates, which are 

 injurious to vegetation, and should be allowed to be corrected by 

 the action of the air before being ploughed in. During this 

 operation the noxious sulphites are converted into gypsum (sulphate 

 of lime). Limekiln ashes are also desirable land amendments ; they 

 contain about one per cent, each potash and phosphoric acid, besides 

 some lime. 



For the destruction of sorrel, heavy liming is recommended, and 

 applications amounting up to two tons to the acre may be used for 

 that purpose. 



Qhalk is dug out and exposed to frost, and then spread, as it 

 is constituted by minute microscopic shells, as well as fragments of 

 shells of larger size ; it contains a little phosphoric acid generally in 



