6o8 Journal of AgncuLiure^ Victoria. [lo Oct.. 191 :;. 



V. 



THE PRACTICE OF LIMING. 

 By A. E. V. Richardson, M.A., B.Sc, Agricultural Suferintcndent. 



The value of lime a.s a means of ameliorating certain classes of soil 

 has been known from the very earliest times, and was the subject of com- 

 ment by many of the ancient writers. During comparatively recent time; 

 there are many instances on record where liberal dressings of marl and 

 chalk have had a most marked and favorable effect on the fertility of the 

 soil for generations. According to Hall, there are certain fields on the 

 Rothamstead Experimental Station known to have received heavy appli- 

 cations of marl more than a century ago, which to-day exceed in productive 

 value adjoining fields which were not so treated. 



That the presence in the soil of a sufficiency of lime in the form of 

 carbonate is a fair guarantee of its fertil ty and productive power is 

 indeed generally recognised, and this view finds its expression in the well- 

 known maxim, " A limestone country is a rich country." 



In this article will be considered briefly the forms in which lime may 

 be applied, its action on the soil, the rate, time, frequency, cost, and 

 mode of application, and the method of determining the soil requirements 

 with regard to Hme. 



I. Forms in which Lime may be Applied. 



These will be dealt with in greater detail in Mr. Scott's article. It 

 is only here necessary to mention that lime may be applied in four distinct 

 forms : — 



(i) As Carbonate, CaCOg, in the form of ground limestone, marl, 

 chalk, " unburnt lime," "dilute lime,'" shells, &c. 



(2) As Oxide, CaO, in the form of quicklime. " hot lime," 



" caustic lime." or "' burnt lime," " unslaked lime," 

 " lump lime.'' 



(3) As Hydrate, Ca(OH)o, m the form of slaked lime. 



(4) As Sulphate, CaS04 . 2H2O, in gypsum, or " land plaster." 

 It is of importance to the farmer tO' realize that the relative value of 



these substances depends mainly on the percentage of lime present in the 

 respective compounds. Now, if 178.6 lbs. of pure ground limestone 

 (carbonate of calcium) are burnt in a kiln, 78.6 lbs. will disappear into 

 the air as carbonic acid gas, and 100 lbs. of quicklime (oxide of calcium) 

 will be left behind. That is to say, 100 lbs. of quicklime are equivalent 

 to 178.6 lbs. of ground limestone or any other form of pure " carbonate 

 of lime." 



Again, if the 100 lbs. of quicklime be thoroughl\- slaked with water, 

 132 lbs. of slaked lime (hydrate of calcium) will be obtained. Finally, 

 if this amount of slaked lime be properly neutralized with sulphuric acid, 

 307 lbs. of " land plaster '' or gypsum (sulphate of calcium) will be 

 produced. 



These figures are of practical importance. It will be seen that there 

 is precisely the same amount of "lime" in 178.6 lbs. of carlmnate or 

 ground limestone. 100 lbs. quicklime, 132 lbs. of slaked lime, and 307 lbs. 

 of gypsum. 



That is, if a farmer wished to purchase the equivalent of i ton of 

 pure lime, he would requ're approximately the following quantities: — 

 I ton of quicklime, 1.3 tons of slaked lime, 1.8 tons ground limestone, or 

 3.1 tons of gvpsum. 



