POTASH AND ITS USES.

New Zealand Herald, Volume LXI, Issue 18685, 15 April 1924, Page 16

POTASH AND ITS USES.

up VARIOUS FORMS DESCRIBED.

(RELATION TO MILK SUPPLY.

; GOOD RESULTS ON CROPS.

. ,' BT PROFIT. Potash, as most gamers know, is one of the essential ingredients in all fertilisers in daily use on the farms. Whether it is used in top dressing mixtures for the various crops, potash in the great majority of cases amply pays the user in the greater increases. in the crop whether it be grains, roots, grass, milk, or even mutton, wool a.rd beef. In the case of meat and wool the value of potash when applied to pastures is proved by the fact that where the grass is luxuriant and palatable, (which will not be the case in the absence of potash), the animals thrive better and fatten far more quickly, while in the case of wool the absence potash is evidenced by » narsh and brittle staple and a lack of proper development

of yolk. are several varieties of potash There are several varieties of potash fertilisers on the market as the following table will show:— Sulphate of Potash containing 48 per can*, pure potash; Kainit (with 2* per cent SCtainin* 14 per potash; 30 per cent, potassic manure, 00 per cent, pure potash.. ~ „ * The first named has all,, oi' P rac^ U f. all of the chlorine eliminated, and it therefore is the most suitable form to use for such crops as potatoes, tobacco tomatoes carrots, parsnips, vines and fruit crops generally, and in the generality of £ses for top dressing pastures. Kainit and 30 per cent, potassic manures contain chlorine in large quantities and should not be used on the crops mentioned. For potatoes, especially they are unsuited as the salt they contain makes them watery and unfit for use. li»y may, however, be used if they are sown on the land to be cropped five or six months before planting so as to let the rain leach out the sat, jril be carried off in the drainage water while the potash is retained by the soil particlcsfbut it is always safer to use the sulphate. These two forms of potash manure are very suitable for mangolds ESS of all kinds, except sugarW, : swedes, soft turnips and for mixtures in top dressing pastures in sandy soils, or on MAt country far inland, where there » nof prSipiSon of salt from sea breezes. L. Potash Removed by MiIS« iThe quantity of potash removed by milk is q much greater than is generally snnnosed. For example a cow giving the ffpSentage of W. of milk per year, takes up from the sod 10 to 121b , phosphoric acid, and precisely the same Quantity of pure potash. There are 1,137 000 dair? cows in the Dominion deduct 10 pea- cent, for non calvers, this i JS?a baiance of 1,023,300, and these at the low estimate of 50001b. of milk for each, remove nearly 10,000 talrfjjJJ potash, the equivalent of 2T,(XO tons of sulphate of potash. What as being done to replace this drain? We are liberal, and justly so, with our dressings of phosphates, but we almost entirely 1 overlook the replacement of potash. l In estimating the amount of milk per cow at 50001b. per annum I am, 1 feel sure, under the mark, but it is safer to i err on the conservative side.. I have not mentioned the nitrogen removed m the I quantity of milk mentioned but it w ! iust double the quantity of either potash or phosphoric acid. However, we need i not trouble ourselves about the nitrogen, ' as the clovers and other legumes, if well Supplied with lime, phosphates and potI ash, more than replace the dram !of *• nitrogen. . These „ figures serve ;to show how exhausting a crop milk is, and how necessary it is to maintain the fertility of the soil in order to keep up the supply of butter, which, with 'cheese, is going to be our biggest export in the near future. It is quite truo that little or none of these elements go away in butter, and when the skim milk is retained on the farm : they are returned to the land, but as 'it in returned per medium of calves and pigs, which are fed in small enclosures, we are fertilising those: small paddocks at the expense of the remainder of the farm. j - '•= ■' Balanced Fertilisers.

( liebig's law of the minimum applies to all forms of manure, that in, that if there is a deficiency of any element the crop whatever it may be, will be a failure, no matter how much of the others may be applied unless the deficient element is supplied. The strength of Jt chain is its weakest link. . Soil analysis is not always to be relied on to demonstrate the amotrnt of any element ;of plant food available for the crop. It may show to an once the quantity of potash, phosphoric add wr nitrogen per acre in the .top ninis or twelve inches of the soil, and how much 'is soluble by the citrate test, but Shis test is not always reliable. For example, Sir A. D. Hall states that some {ilant. food—phosphoric acid, if my memory s not at fault—which was soluble in a one per cent, citrate solution (two per .cent, is the standard), for some obscure reason was not available; for the plants. To come nearer home, the writer knows of a case in Waikato, where the farmer, who intended sowing oats, sent samples of soil from various parts of the paddock for analysis, and was told there was plenty of available potash, and it was ■; therefore quite unnecessary .to apply any in the manure. He thought it advisable, notwithstanding the chemist's dictum, to experiment -with some. He gave a dressing of manure without > potash to half the paddock, the. other _ half receiving the same quantity plus sulphate of potash, the difference in favour of the potash treated part was most marked, so much so that even the eyea most unreliable guide in such a crop —could not fail to see the good result of potash manuring. .'

4 Value of Clay Soils,

As ' a rule clay soils,contain great stores of potash, but though the reserves are often ,very great, they, are by no means always available for the plants. The writer made a test with parsnips in a clay loam, naturally well supplied with potash. ' Manure with sulphate of potash was applied to all the rows ._ but one. When the potash treated rows were a foot high and too tops a deep green, the check row was stunted and yellow. Sir. A. D. Hall states that one of the paddocks ' in Rothamstead Experimental Farm contained 95001b. of potash to the acre in the top 12 inches of soil, yet the plants languished for lack of potash, and when artificially supplied they flourished. All the potash that was capable of being acted upon by agents had been used up, and as there was no more available it had to be supplied in a soluble form. Lime, we know, is a great releaser of potash, so is the sulphate of lime in superphosphate, but very often the potash in the soil is in such an intractable form that jo pays to apply some soluble form. In such instances Kainit or 30 ner cent, potassic manure is not a suitable' form to use, as they are liable to form a hard n«L B : on *£ he , snrface - Sulphate in such a wl,r % i eSt - Eat if the land is infested wiUi the grass grub, Kainit is the ace 'toSJe *"**■ £** to foUr cwt ' per Vas,; j£E?h. *' lth n same weight of j£ th*ss 6 y efiective in <&troy-