LIMING OF SOILS.

Sun (Christchurch), Volume III, Issue 882, 7 December 1916, Page 9

LIMING OF SOILS.

AN INTERESTING PAPER. An interesting paper on "The Lime of Soils," by Messrs L. J. Wild and J. G. Anderson, was placed before the Philosophical Institute of Canterbury last evening, by Mr Wild. In an oral summary of the paper Mr Wild stated that it is the sequel to one read last year, in which an account was given of the llutchiuson-MacLeunau method of determining the lime requirements of a soil, and in which some experiments relating thereto were described. The present paper describes (a) a practical test of the reliability of the method (b) an investigation of the theory of the method. A visit was made by the writers to Southland, a district where liming is considered by the farmers to be essential to success, and there soils were collected from adjacent paddocks, one of which had been limed and the other had not. On estimating the lime requirements of such soils by the Hutchinson-MacLennan method, a difference was found which corresponded in some measure, though not strictly, to the actual treatment received. Another point observed was tliat soils, even after field treatment with sufficient lime to satisfy them' so

far as is indicated by their cropping capacity, still show a "lime requirement." In Canterbury,' where liming has not taken on with the farmers to any extent, the soils are found to have a considerably lower "lime requirement" by this method than Southland soils. The authors believe that the method gives a satisfactory comparison of the lime requirements of two soils; to find the absolute requirement for a given soil a correcting factor is necessary, which for Canterbury Plains soils is believed to be .10 per cent. (minus 0.10 per cent.) worked under standard conditions. The method gives indications which are more reliable than those obtained by the ordinary methods of chemical analysis. Requirements indicated for some Canterbury districts are: Morven, nil; Lincoln, Rakaia, Ashburton, 1! or i cwt. per acre. An investigation of the theory reveals evidence that the disappearance of lime from the solution used is due in part to its absorption bj- the soil colloids.