USE OE POTASH

Press, Volume LXIX, Issue 20937, 18 August 1933, Page 7

USE OE POTASH

EFFECTS IN FERTILISER TRIALS PROBLEMS OF EVALUATION "Of the several elements of growth generally employed iu fertiliser trials potash is probably the most difficult to evaluate in effect," said Mr L. Napier, of Pacific Potash, Ltd., Auckland, in a paper read yesterday to the conference of the New Zealand Grassland Association. "That is thought to be so for several reasons. The high power of absorption of potash possessed by most soils must always be a factor. Apparently, too, the diffusive properties of potash vary markedly under different conditions, of sojl, temperature, and moisture. Yet it is less in these respects than in another that potash experiments on pastures present their major complication." Differences existed in the appeal and value to the beast of grasses and clovers which had not yet been traced t<) their source, said Mr Napier. It did seem reasonably certain that taste played no inconsiderable part in the grazing preference of stock, and it was common enough to ilud potashtreated pasture, which to the closest human observation presented no special feature, heavily grazed in a fashion which irresistibly suggested a strong predilection on the part of the animal. As had been suggested, this might be due to a taste-difference, or again to an instinct which informed the beast that pasture with a high potash content was of special value to it in its productive processes. It was, indeed, not impossible that both taste and instinct governed this phenomenon. Sait and Palatabilily. It had frequently been suggested that it might be to the common salt content of kainit or potash salts, that one could look for an explanation for this taste preference. This did not seem very probable, first, because sulphate of potash which at most contained a mere trace of sodium chloride, v/as just as effective as kainit in this respect, but second, since the special, palatability of potashtreated pasture had been shown to exist for years after an initial heavy dressing; that was to say, long after all trace of the common salt content of the lower chloride combinations had inevitably been moisture-carried far down into the soil. _ "Some day it will no doubt be possible to arrange comprehensive pasture trials in New Zealand specially designed to tract the real effect of applied potassium on a wide variety ol' soils, taking into careful consideration those special potentialities of the element, of which an outline has thus been sketched," said Mr Napier. The ejmple "observational plot 7 ' system at present generally relied upon by the Department of Agriculture is no doubt regarded purely as a preliminary to more radical work. Yet the system ooes contain . intrinsic disadvantage. No "observational" standard can possibly be fixed, so that it is doubtful if, say, five successive "observers" independently examining the layout of, perhaps. 10 sets of "observational" plot? on the same, day, would in their placmgs" of the plots, achieve anything even remotely approaching unanimity. And were the examinations to be spaced by even a few days, the prospect of reproducing the various observations in a dependable report would seem to be even further prejudiced. However, the need for systematic research in -.this .country into ttese and

aliied matters will sooner or later bring its own remedy. Even In the troubled state of the world to-day, scientists in many lands are delving from every angle into the problems connected with fertilising, and therein at least lies hope of progress,