A VALUABLE FERTILISER.

Otago Witness, Issue 3889, 25 September 1928, Page 13

A VALUABLE FERTILISER.

BASIC SLAG FROM BELGIUM. One of the most valuable fertilisers that has come into general use in recent years is basic slag, a by-product of the steel industry. The chief source of New Zealand’s supplies of basic slag is Belgium, whose steel mills produce highgrade slag of high solubility. In an address to farmers during his recent visit to the Dominion. Sir John Russell, directo- of Rothamsted research station, and an eminent authority on soils, said basic slag owed its fertilising value to its phosphate content, and also to certain other elements which were not exactly known. Figures supplied by Mr Armand Nihotte, Consul in New Zealand for Belgium. show the growth of the export trade of Belgium in artificial fertilisers as follows:—

By far the greatest part of the above production was sent to Germany. Last year 47,000 tons of basic slag was imported from Belgium into New Zealand. • I'll 6 ! bulk °f the basic slag production in Belgium comes from the great steel mills of the John Cockerill Company, of Seraing, which bears the name of its English founder, last year celebrated its centenary, and, to-day employs 10.000 workers.

PHOSPHORIC CONTENT OF SLAG. Mr Nihotte recently received from Brussels a copy of a report to the Minister for Foreign Affairs, from the John Cockerill Company, on the quality of the basic slag produced for the New Zealand trade, which is of interest to Dominion farmers.

The report states that the total annual output of the Cockerill works is approximately 100,000 tons of basic slag, containing *en average percentage of 17 to 19 per cent, of totally soluble phosphoric acid in mineral acids, with a minimum of 85 per cent, of solubilitj 7 and fineness. “ Until now,” continues the report, “ we have placed very little slag in New Zealand on account of the sales conditions imposed over there, and especially because the richness of our elag in phosphoric acid, soluble in citric acid 2 per cent. Wagner process, enables us to place the totality of our output in countries buying on that basis. With regard to the sales conditions, it is necessary to remember that basic slag is not a manufactured product. It is only a by-product of the fabrication of steel. It ie this last fabrication which is regulated and dosed by the producers, and analysis of the by-product, the slag, being what it can be in the conditions where the producer has.judged that the elaboration of the iteel had to be made. The amount of phosphorus in the slag is consequently essentially variable, and the imposition of a fixed amount is equivalent to favouring either fraud or mixing. “ We understand perfectly well that the minimum percentage should be imposed in order to eliminate slag which would be judged the poorer, either from the fertilising point of view, or the transport expenses, but the rational mode of payment is the integral payment per unit, based on the , analysis effected under Government control, or by an arbitration known to .be experienced in the matter. The percentage of the slag being very variable, it is practically impossible for the producer to realise the fixed percentage of 17 per cent., and to remedy that inconvenience, either the shipments are not made of the slag with a regular percentage, but with an average of 17 per cent., or to cover himself for the excess of percentage which would not be paid, the supplier quotes his price per ton consequently. "It appears more and more evident that alone the phosphoric acid soluble in citric acid 2 per cent, process Wagner has an immediate fertilising value.

Concerning the packing, until now we have supplied in different circumstances our slag in 2001 b double bags, and we have never received any claim from the customers. With regard to the supply in double bags (16 bags to the ton), it is only a question of getting a supply of suitable bags of that type. This method,

of course, entails supplementary bagging expenses, and has an influence on the sale price.

Superphosphates. -‘Pons. Basic Slag. Tons. 1925 . .. 176,240 802,835 1926- . . .. 282,329 913.827 1927 . .. 255,564 1,005.956