LUCERNE, LIME, AND HUMUS.

Press, Volume LVII, Issue 17317, 1 December 1921, Page 10

LUCERNE, LIME, AND HUMUS.

1 ; . to THB ZDiTOB or "THE PRESS." ' V' t£r,— During the discussion on i the subject or ludprne-grcrwing some "5 ideas were giyen which, -if followed, : i might land th& grower in trouble. .This ' is my excuse for writing this letter. Mr * Parian'd, in' one'of his contributions, i unburdened himselfof the following: ''laming—-Mr Macp/herson says, 'Use • 'J burnt June.' This, is not suitable unless injieaty Boib,whehthere is an excess of : humus. On. dry or naturally ..drained - • soils bixrxK& lime aerts quickly, burning up ■ the humus and. creating plant tooa ■ quicker than is necessary, and these in- < . gradients, if not absorbed by the plant, 'jget wftshed avray. . . ; the best to apply lime is in the finely ground ! cartenate-fonn." " :i '< Against" .-this I will give ; what some* •j body else Bajrß. In a pamphlet issued ; > ii. 1910 by the West Virginia University T Agricultural 'Experiment Station,_ en- ■ titled ' 'Commercial Fertiliser*,'' written by B. H. Hite. and cnemißt'i and"F.*B. Ktinst, A.8., assia- ' ' Ntant che|Durt,'.the'q[ueßtion.'of ''humua'' • and. use of "burnt lime" ! , is jreferred .wAs follows: —''There is nothing to bk-jfiuged by using; ground tun®. • ibk* the welCfenown burnt of fact. ti» buGrt

lime acts more promptly, and pound for pound is nearly twice as efficient. Cutting freight bills in two, no one should be afraid to use the burnt, lime; I nor should anyone pay double Treight bills on the ground limestone because i somebody tells him that the burnt lime will 'bum up the humus.' Humus, inci- ; dentally, performs so many other valuable functions in the soil that we sometimes seem to forget that its one great work is to burn up. In burning up it exerts a more powerful solvent action 1 than any other known agent on the soil's dormant stores of mineral plant food. The only hope for sour soils is that humus may again be made to burn in them as in the virgin soil. Strictly spenking. it is not the lime but tlie soil bacteria that burn up humus, and so far as anyone has been able to suggest these were put in the t soil for no other purpose than to 'burn up' humus Lime cor- < rects the sourne?s, and so restores the ! conditions v.nder which the bacteria : can proceed with their work.". From a pamnhlet published in 1919 by the New York State College of : Agriculture, at Cornell University, en- . titled "The Use of Lime on the Soil," the following extracts are taken: "In recent years the Agricultural Pross has devoted much space to the socalled dangers arising from the use of caustic (burnt) lime as compared with carbonate forms of lime. In opposition to that discussion, it may be considered that in general practice it is safe to use whichever form supplies the most available 'lime at the least cost, when npplicd to the soil. The chief objection that has been urged against the use of caustic (burnt) forni3 of lime is that the lime in these forms, as a "result of the caustic properties, destroys the organic matter of the soil and releases the nitrogen. Careful investigation haa shown this reasoning to be unsound as applied to the use of caustic (burnt) lime in such amounts as are needed to correct soil acidity. ... I>r. Macintyre has found that even when a large quantity of caustic (burnt) lime is mixed with the soil, thero is no evidence of the destruction of organic mafter. . . . Moreover, caustic (burnt) lime is freely used in tanning leather, in clarifying sugar, 1 and in making paper, and if it had any destructive action on 6uch organio material it would not be used in these operations. Consequently the idea that caustic (burnt) forms of lime chemically destroys organic matter may be dismissed. ... "Contrary to the usual statement, 3 Frear (Professor, Pennsylvania Depart- « merit pi Agriculture) has shown from I calculations, based on the Pennsylvania ] plots that more organic matter has actually been destroyed yi the soil of theplots receiving carbonate of lime than where caustic (burnt) lime was used. This was particularly true when the lime was used in connexion with manure. ... "There is an important distinction between carbonate of lime and caustifc (burnt) lime in their effect on the microscopio organisms in the soil when first applied. Caustio forms of lime bring about a larger change in • the numbers and type of such organisms /than does carbonate of lime. . . . In this way caustic (burnt) lime may have marked beneficial effects on the soil which are not brought about so readily by carbonate of lime.'' No other forage crop requires eo much lime in the soil as lucerno. There is strong evidence to prove that lime is essential ,to the growth of lucerne. A chemical analysis of lucerne shows the presence of nearly 35 per cent, of lime, indicating that. lucerne is a ravenous consumer of that substance. No wonder then that lucerne refuses to grow and properly, develop in soil that is devoid of lime. In all demonstration areas under my charge, at the Christchurch Exhibition in 1906, the Auckland Exhibition _ 1913-14, the 1 Panama Pacific Exposition, San. Fran-- i cisco, 1914-15, right on to now, on all , classes of soils, heavy loams and clay 3, i light Shingly; and"poor soils, to drift- \ ing sand areas at Sumner, New. Brigh- | ton, Dunedin, and Cotlih's riyer, ThavcS j consistently tod lime iu the burnt or , caustio form, never using less than one j ton per aore, more often 'much Heavier j dressings, • with none but beneficial re- \ suits. * One ton of ground burnt lime is nearly equal to two tons of' car- j bonate, thus cutting freight and haul- , age costs in trarb, which, is a mighty consideration in farm economy these 3 days.—Yours, etc., * . . -± MAOPETERSON, Christchurch, November 29th. j