ARTIFICIAL MANURES.

Taranaki Daily News, Volume LI, Issue 170, 9 July 1908, Page 4

ARTIFICIAL MANURES.

BASIC SLAG. Farmers at this season of the year are considering the question of manures, and from the varieties offering have to select that which they consider best suits their requirements, it cannot be gainsaid that Taranaki as a whole, would benefit vastly from ;i comprehensive top-dressing and renewing of worked-out pasturages, and the day has gone by when farmers consider artificial manures as " nowt betler'n stands on zoe-;.horc," as a local worthy wa» ouce heard to express his wisdom. In order that fanners may form -onie opinion regarding the respective merits of manures, we have arranged to publish the properties of the superior grades of the different fertilisers on the market, from information supplied from the best available sources. Basic slug has sprung into public favour so rapidly during the past fewyears that some information concerning it will be of great interest lo farmers generally, and especially to dairymen. Slag is one of the most, if not the most, valuable of our phosphalic manures for pasture lands. No other fertiliser seems to give such satisfactory results both in quality and quantify of herbage as this. Many tests have been made ill various parts of the Dominion, and in nearly every instance slag lias given the mosi profitable resulls. Especially has I his been the ease on poor lands and wornout pastures. The (loverniiient experiments at the Wnirenga Expcrimciil.il Farm are a striking instance of this. There, on clay land so poor as to be apparently valueless, results were obtained by Ihe use of slag which fully justify the high reputation of tin's manure, it is true the dressing—hall a ton •per acre—wits much heavier than any private farmer could apply, but the results justified the expense, for the resultant pasture was quite equal to anything dial could be grown on land valued at C3O an acre, and Ibis on soil so poor that at the very outside it could not be assessed at more than ten shillings an acre. A heavy dressing such as the above would last for eight or leu years without any further application. Experiments carried out in llritain and on the Continent have proved thai one heavy dressing is more profitable and in ■the end more economical than three or four light annual ones aggregating as much as one heavy application. Basic slag is much more permanent in its effects than superphosphate; it is not so quick ill its action, but its residual value is greater. Superphosphate, of course, (ills a position in fertilising that no other manure can possibly fill; that is. its activity in stimulating the early growth of crops—as, for instance, turnips, which it hurries into the rough leaf stage, and so enables it to get 1 ahead of the destructive (ly. After that stage has been reached the slower acting manures carry tlie bulb to a successful I maturity. Dr. Aitlcen, of the Highland ] Agricultural College, gives it as his | opinion, based on a long series of exI perimeuls. that weight for weight slag is a better manure for turnips than I superphosphate. In Ibis country possibly that may H rd be so; it. would entirely depend on the rainfall, for should a dry season set in then slag would lioi do its work so well. It is, however, more quick acting than bonediisl, and there is no doubt'that with a combination of slag and super, witli the addition of potash, very gooil results could be obtained in growing turnips. Care, however, must be exercised in such mixing; three parts slag and one of super are about the correct quantities, ami j then the mixture should be made in the paddock and used immediately, so as lo prevent caking. As slag is such a valuable manure it would be as well to utter a word of Million and advice to farmers when they make tlieir purchases. There is no fertiliser in which there is sin h a variety of grades as this; some of it i~ as lloiv as S or 10 per cent, of phosphoric acid, while the good grade ranges from 17 lo 20 per cent. It is perhaps needless to say that the lowest grade is not worth buying, for the freight is the same on each, and every farmer knows, if he reflects for a moment, that the higher-priced article is infinitely cheaper as well as more effective than the low grade, for it takes so much more of the latter lo do the work as well as the other. Then there is the mailer of fineness, which is of paramount importance, for unless the slag is ground to an extremely fine slate of division it is not readilv soluble, and is conscquentIv less effective: and it is a fact that the low grade article is not ground so finely as'l lie high.. From this it will be seen, looking at the matter I'r the point of fineness and quality. Ilml Ihe inferior grade is not worth buying at any price.

■Slag is sold (in I hi' basis of pc (Tillage uf phosphoric nciil. X"W phosphoric ;u-iil is expressed mi llu- iuvoic.-ecrlili-rales as L'2 00, anil iU equivalent in tri calcic [i|i(is|iliulc is given ill Hie n"NI column, the liiUci- being Hi,. (.•.-liiiiial name of phospbale of lime. In ord-r lo liml Hie phosphoric acid contenls of any given plmspltalie manure, tntilliply the unit.- i.f plmspiialc uf lime or hi-cal.-ic phosphide liy . laS anil the ivsiill will lie phusplmi-ic acid.' Fur e\ainp!c. slag of 28 per cent, phosphate of lime eonlniiis only 12.x phosphoric acid, and Wl jii-r ccnl. conlains 13.7, a von- low grade iiulocd. which, to say the least of it. is inadvi-alilc to buy. Clnoil grades of slnS range from IT t<> 20 per cent, phosphoric acid, and tu find the eipiivalcut of ii'osphale of lime in these multiply the in": ■ by 2.153 ami the result is pirns])li." ' of lime, or in odiei' words, tricalcic phosphate. Il is only noccs-aiy for the farmer lu licar these inures in mind to bu able to form an intelligent idea of the value of (lie various grades. The following table will show the units of phosphoric acid and their equivalent in tricalcic phosphate: rimspharic acid Tricalcic phosphate ■per cent. (or plios. of lime) in :j4.!)2 IT :J7.11 IS 3!).2!l in 41.17 20 43.00

~A As (lie unit value of phosphoric acid is about 4* 0d (some chemists estiiiint:; '. it at as), it is only necessary to multiply the units by Is (Id to lind the dill'erencc in value belwen the low and high grades; for instance, the difference in value between l.'l per cent, and 10 per cent, slag is :l units, which multiplied bids (id is l:',s Od. the difference in value per ton. A f*mcr who does not knew these simple rules can very easily be deceived, for when he gets quotations il is the easicsl tiling in the world to mislead him. Say, for example, he goes to A, who quotes hi,,,, sav. C."> for slag guaranteed not less than 10 per cent.-, lie then goes to I!. « ho quotes ft I.ls for what he says is 2S per cent, slac: tlie buyer naiiirally thinks lie isgcUim: much greater value from li. bill he does not know (hat the 2S per cent, is phos phate of lime, not phosphoric acid. ,is was quoted by A. The diircrcncc in the price is o„]y ,",s. l.ut the iliO'ci-eiiec i,i value is Us Od in ehemieiil analysis alone, without taking into consideration the difference in fineness. The standard of fineness laid down by Professor Wagner is 7.") per cent, llirough Hill mesh, namely. 10() holes to the lineal inch or Ifl.nnn („ the square inch, and iiollii'iless than this -I Id be accepted. Some high-grade -lag i- even liner than I hi* tanners should insist „,, having the percentage expressed ... ,-lcarlv (hat they in.iv be certain of knowing wholhe,it is phosphoric acid or phosphate o! lime that is implied, bui a safe guide is that when they hear of 2S and upwards stated they can be absolutely certain it is phosphate of lime or tricalcic phosphate, ami by applying the method above given (hey can then compare il with that which is staled ai 10 per cent, and under 20. As a matter of fuel, where 10 per cent, is guaranteed the tanner may rely on its being Is or over, the nierehanl guaranteeing the lower ipianI lity for se)f-,,r0tee1,',„,, as lie-conditions of the .Manure Adulteration Act arc so stringent (hat a difference of only .11.1 per ceul. less Ihan his guarantee renders him liable to a prosecution, hence I he necessity of the minimum figure. Mr. Sergei, of Wtham, carried out some experiments wilh slag and potash on grass land with very marked results on the quantity and quality of lie milk of tli- ( cows grazed on the n ui-ed pasture :e. : ' iigaui.it uiiinanureil. The- -dag in Ibis I 1 iii.slance was guai-anlci-d 10 per cent., I but as a niatlci- of fad- llie real analysis n

was 18.61 on the certificate of the Colonial Analyst. From the above it will be seen how very necessary it is for farmers to buy only the best grades of all manures, for in the end they are the cheapest. 'Phosphoric acid is the active, or concentrated, inanurial constituenl of phosphate of lime. All chemists in valuing piiosphatic manures value them on the basis of phosphoric acid.