BASIC SLAC PRAISED.

Dominion, Volume 1, Issue 202, 20 May 1908, Page 3

BASIC SLAC PRAISED.

In connrction with the experiments being conducted at tho Ruakura State Farm in top-dressing for paddocks (says our Auckland correspondent) farmers ivlio were .present on Thursday were very much interested in the results obtained from using basic slag and the other manures, which had been tested in a field dividod into nino different portions. The basic slag gave incomparably the bost results, particularly on the allotment, which was dressed three years ago with'lOcwt. to the acre. Where'this quantity was used a permanent sward of beautiful pasture was produced, which will probably last ten years without, re-dressing. So far there is no sign of any falling off in the quality of the crop, which is as good this year as ever.

The value of basic slag is a mattor of much difference of opinion. This is probably due as much to variations in tho quality of tho slag as to difi'c.ront modes of application. It is alleged that slag is sometimes sold that i 3 very poor in phosphates, and farmers who may be influenced by tho Ruakura results should therefore be careful to ascertain the strength of the material tliey purchase. It is made in steel works in the course of the purification of iron oro, and only those ores rich in phosphates produce a .valuable slag. Slag is

insoluble. Theoretically, therefore, it should not bo used as a top-dressing, bccauso insoluble. matters cannot travel (lovrn int-o the soil. It is found, however,' that the 4-limo phosphate of slag is so unstable, as comparod tfith the- Si-lime phosphate of' bones, that it beconios slowly solublo, and available for tho uso of such plant roots as feed near the surface. The -good effects of slag are attributed, in addition, to tho presence of largo quantities of lime and iron, iron being particularly beneficial to Auckland soils. Coarse siag, however, is insoluble, and almost valueless. Here are' two analyses of good average basic . slags:— 0 , Sample A. Sample B. 0 Lime, per cent.. •. 50 55. a Phosphoric acid, per cent. 18 17 Oxides of iron, etc., p.c.... 22 12 ® Silica, per cent 7 — " Magnesia, per cent 3 —