POTASH AND ITS USES.

Shannon News, 6 May 1924, Page 4

POTASH AND ITS USES.

VARIOUS FORMS DESCRIBED. RELATION TO MILK SUPPLY. GOOD RESULTS ON CROPS. Potash, as most farmers know, is one of the essential ingredients in all fertilisers m daily use on the farms When ever 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 crops whether it be grains, roots, grass, milk, or even mutton, wool and beef. In the case of meat and wool the value of potash when applied to pastures is proved by.the fact mat 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 tne absence of potash is evidenced by a harsh and brittle staple and a lack of .proper development of yolk. There are several varieties of potash fertilisers on the market as the follow ing table shows: — Sulphate of Potash containing 48 per cent, pure potash; Kainit (with per cent. Peat) containing 14 per cent, pure potash; 30 per cent, potassic manure, 30 per cent pure potash

The first named has all, or practically all, of the chlorine eliminated, and it therefore is the most suitable farm to use for such crops as potatoes,' tobacco, tomatoes, carrots,, parsnips, vines and fruit crops generally, and in the generality of cases for top dressing pastures. Kainit and 30 per cent, potassic manures contain chlorine in I 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. They may, however, be used if they arc sown on the land to be cropped fivh or six months before planting so as to let the rain leach o,ut the salt, which will be carried off in the drainage water while the! potash is retained by the soil particles, but it is always safer to use the sulphate. These two forms of potasli manure are very suitable for mangolds, beets of all kinds, except sugar beets, swedes,'soft turnips and for mixtures in top dreseing pastures in sandy soils, or on light country far inland, where there is no precipitation of salt from seabreczes. Potash Removed by Milk.

The quantity of potash removed by milk is much greater than is generally supposed. For example a cow giving a low percentage of 50001 b. of milk per year,’ takes up from the soil 10 to lglb. phosphoric acid, and precisely the same quantity of pure potash. There arc 1,137,000 dairy cows in the Dominion, deduct 10 per cent, for non calvers, this leaves a balance of 1,023,300, and these at the low estimate of 50001..-. of milk for each, remove nearly 10,000 tons of pure potash the equivalent of about 21,000 tons of sulphate of potash. What is being don e to replace this drain? We are liberal, and justly so, with our dressings of phosphates, but we almost entirely, overlook the replacement! of In estimating the amount of milk per cow at 50001 b. per annum I am, I fool sure, under the mark, but it is safer to err on the conservative side. I have not mentioned the nitrogen removed in the quantity of milk men-

tioned, but ic is just double the quanti ty» of either potash of phosphoric acid However, we need not trouble our

selves about the nitrogen, as the clovers and other legumes, if well su'pX>liecl with lime, phosphates and potash, more than replace the drain 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, witih. cheese, is going to be our biggest export in the near future. It is quite true that little o.r none of these elements go away in butter, and when the skim milk 3s retained on the farm they are returned to the land, but as it is returned per medium of calves and pigs, which arc fed in small enclosures, we are fertilising those small paddocks at uie expense of the remainder of the farm. Balanced Fertilisers. Liebig's law of the minimum applies to all forms of manure, that is, that it there is a deficiency of any element the crop whatever it may be, will be a, failure, no mutter, how much of the others may be applied unless the deficient clement is supplied. The strength of a chain is its weakest link. Soil analysis is not always to be relied on to demonstrate the amount of any' element of. plant food available for the crop. If may show to an ounce the quantity of potash, phosphoric acid or nitrogen per acre in the top nine or twelve inches of the soil, and how much is soluble by the citrate test, but this test is not always reliable. Po.r example, Sir A. D. Hall states that some plant food —phosphoric acid, if my memory is not at fault —which was soluable 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 WaikatOi 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 unneccsary to apply any’ manure. He thought is ‘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 receiv ing 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 eye—a most unreliable guide in such a crop—could no.t fail to sec the good result of potash manuring. Value of Piny Soils.

As a rule clay soils contain groat stores of potash, but although the reserves are often very great, they are by no menus 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 created rows were a foot high and the tops a deep green,, the check row was stunted and yellow. Sir A. D. Hall states that one of the paddocks in Rothamstcad Experimental Farm contained 95001 b. Of potash to the acre in the tap 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 hart to be supplied in a soluble form. Rime, wc 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 intratratable form that it pays to apply some soluble form. In such instances Kaniit' or 30 per cent potassic manure is not a suitable form to use, as they are liable to form a hard cake on the surface. Sulphate in such a case is the oest. But if Ih e land is infested with the grass grub, Kainit is the best to use. from three to four cwt. per acre, together with th c same weight of basic slags, is generally effective in destroying the pest. - j