KING COUNTRY LIMESTONE.

King Country Chronicle, Volume I, Issue 26, 19 April 1907, Page 3

KING COUNTRY LIMESTONE.

Crude Lime on Grass Land. The immense quantity of limeston rock existent in the King Country, besides being an indication of the excellent quality of the land, has been utilised, in various way?, for industrial and agricultural purposes. Already a great quantity of burnt lime for agricultural purposes is being turned out from Messrs Wilson and Son's works at Te Kuiti, and the product is also being largely used in the building trade. In addition, both the firm mentioned, and Mr Lovett, export great quantities of the stone, broken to various sizes, for metalling and other purposes. However, the limestone industry, so far as the King Country is concerned, is practically in its infancy, and in the natural course of events must grow into one of the chief industrial features of the district. Lime has for so long been recognised as a valuable fertilizer, that it is not to be wondered at, that new ideas and experiments have been tried with the view of turning the material to account in various ways. Mr T. Pine, of Te Kuiti, is an advocate of finely powdered crude limestone as a top dressing for grass lands, and is of opinion that by using the material in this - way, besides doing away with the expensive process of burning, the effect on the land treated will be more enduring, and give better all-round results. Mr Pine is now conducting experiments on a small scale, and .the results should be highly valuable to a district so largely provided with stone, containing such a high per centage of lime, as the King Country. In the same connection it is interesting to note that the Agricultural Department for the county of Lancaster, England, has been conducting experiments with the object of ascertaining in what form a dressing of lime can be best given. As the report says it is a common custom when liming land to apply the material as cob lime (called also lump lime, burnt lime, shell lime, and quick lime), in small heaps placed regularly over the field. In this way the lime, acted upon by the influence of exposure to the atmosphere, is converted into a fine powder called slaked lime, most of which, in a shorter or longer time, combines chemically with the carbon dioxide of the air, and becomes once more carbonate of lime. As the cob lime is converted again into its original 'condition, carbonate of lime, what, it may be asked, is the advantage of applying the more expensive : cob lime ? The advantage arises from the much finer condition of the material after it has been burnt and becomes slaked lime.

Recently crushed lime produced by grinding the cob lime by suitable machines, has been put upon the market. It can be spread more evenly over the land. Being burnt lime, the chemical changes indicated above take place, and it becomes carbonate of lime, in a very fine condition, distributed evenly over the surface. The question arises, seeing that the burnt lime becomes carbonate of lime, whether ordinary limestone rock —carbonate of lime —ground to a fine powder and evenly distributed over grass land, might not prodnce results equal to those obtained by cob or burnt lime, and thus dispose of the expensive process of burning the rock. This is the question the experiments were undertaken to investigate, and the conclusions arrived at, are thus summarised :

I. Taking into account the results obtained, at the county council farm in the two years, 1905-1906, and also the price per ton, crushed limestone can be employed economically upon pasture land where a dressing of lime is needed.

2. According to the results obtained at the various farms in the county, the more finely divided forms of lime are more immediately effective than cob lime. The results indicate, also, that crushed limestone is a more profitable dressing than cob lime, and the following remarks are added : —ln districts where, owing to the nearness of limekilns, it is more convenient to use cob lime, it is essential that the lime be spread from the heaps as soon as fallen, and, in order to ensure more effective distribution, 'the light harrows should be passed over about two or three days afterwards, so as to scatter any lumps that may not have fallen in the heaps. Crushed lime should not be delivered at the farm until all arrangements have been made for its application, as loss will be occasioned by the bursting of the bags. The lime should be finely crushed so as 35 per cent, will pass through a sieve with 10,000 holes to the square inch, and should contain about 90 per cent of lime. 3. When crushed limestone is used it should contain a large per centage of fine powder ; it should also contain a high per centage of carbonate of lime. When the purer limestones are used for the preparation of crushed limestone, the per centage of carbonate of lime may be higher than that given in the usual analysis table, viz., 95 per cent.