The Action Of Plaster As A Fertilizer

Perbaof no subject couoeeted with agricultura, says tn'e AertuUunst. bas gnen risy to more .-pi culatioti t h -in the C tl on of piaster orgvp-imi on vegKitirrti, Wliv it sliould i irui I u;o snelt s'nkint; resulta at. nne Mm , why it is apparently u-tless at oiIihis, or why it s-hoold be beneficial at all, huve been problems wbioh the :t Lii'icul'. uial ebemvfttS huve found difEcnh ol -olu'inn. Tlie oolumni of sim of our coteinporaries have reeeittiy been oicupted with corumuuicatioiiN upon the subject, wbich poived to show a l:ick of clieinical kunwle Ige npoo the purt o) he writurs, witlu -ut increas iiifi th it of the reade'S. In oases like tb', 01. e direct experinievit is worth host of speiüilations, and M l)eherain _of Frauce, haf, liy I1Í8 latuirg in this di rection, tri ven us some light nim this liiueh Texed oubject. Thene -xperiiiiei)ts indiuüte thüttliu use of pla-iter i-1 niainly to liberale the potash contained in the niioeral conBtitueptB of the soil. In the disintegrüied rockg if which the soil is totTipost-rl. pcta.ih esigtn in an ingolnble coinbitiatioii. Tl e phisier is sulphate of linie, which ia soluble, and when this, iti the rno;-t -tatú, is io i ontact with min ertilw coDtaininK potnsh in an insoluble fonn, tlie lime and pornwh chanife places. The po'.asb is libriated, wbile the 'iiae of the pla-ter takes its place in the iusoluble luiiierul. Tliis chanae is eflectod very rapidly, a it was shown that. soit wbiuh coMtuine1 only a trace f potash, tve, 12 hours af er the applicatioo of platiter, un appreoinhle amount of that sudstanee. Aiiot.lier effect of piaster has been sutrgusted by Prof'. S. W. John moq in M:s leotureo at the Soiithnonian in.stini'iiiM. Il has been fo'jud by ex(icriimv't. rtint the pivsence of ci'rtain íOTítáííces, plaat er amoDg tlmreít, in tb juico '( t plant, hus a tnarked tendency 'o prevent evuporatiou by ttie leaves. - tt w, of cour.su ottcesfarv that a certíiin jnxmn' ol the liij'iii contouts of ihe plant s'muld püss o(T m this way, bnt in u very ilrv timH the uvapofiition may bo more rapid thttn the pocens of vegefttion ileiutitids. Tlie ose of piaster upon the soil luiiv enablo a erop to wltbgtatid a droath much better than upon unplastered bind.