Stock-licks in Dry Seasons.

Cromwell Argus, Volume LXI, Issue 3167, 15 June 1931, Page 6

Stock-licks in Dry Seasons.

13. C. Aston, Chief Chemist, Department of Agriculture. The aphorism "the soil is the child of the climate" has not received that general recognition in New Zealand which the truth warrants. It is movo especially in the South Island that the influence of climates on the same soil formers results in different types oi farming 1 developing in ccas having different rainfalls, the soils heing derived from rocks of the same com]|/>sitioi* originally. In the North Island droughty seasons occur in the YVairarapa and Hawke's Bay areas, and occasionally in Taranaki, but there is not the same constancy in climate that there is in the South Island. A study of the local meteorology ra»»y reveal a reason for low returns from stock when other conditions of environment do not offer an explanation. It is from the soil that the pasuato obtains those mineral foods so essential to both plant and animal. One ..1 the most important constituents of t?.e soil is water, which acts as a carrier of minerals from the soil to the plant. Pasture plants takoi up undca" favorable conditions much more nfinaral food than they require for healthy growth. This fact is utilized in farming to make the pasture convey more mineral food from the soil to the a-n: m a I in a palatable form by top-dress-ing the pasture with mineral fertilizers. At the same time the pasture is made hv tills means more attractive and nutritious, and the production of j axture and therefore the carrying-cap;*..• ty per acre is much increased. Top-dressing mixtures do', not., as at present used, intentionally incl'ilc some mineral foods essential to the animal, because these; do not increase production of pasture. It is customary to give such minerals to the animals direct as a stock-lick. Examples ol these mineral foods benefiting lie animal but not the plant are sodium and chlorine given as common ••.atfc (sodium chloride) ; iron—highly necessary in some sandy perhaps peaty dis tricts —given >.:s citrate, .carbonaVa, or hydrated oxide mixed with the salt;' and iodine given in minute closes with' the salt as potassium iodide. Special crops such as mangels, asparagus, and some others benefit by applications of- salt as a manure, while potatoes and some other crops may have iron sulphate and profit by it-; but. pasture is not in general practice dressed with salt or iron, although both may at times be) applied as impurities in the fertilizer used—salt in kainit or potash manures, and iron in oasic slag. ,\ somewhat sharp distinction any uiereiore oe matte in considering m_.ai ioous ociwueu ones wnicn increase oi pasture 01 carryiuyup.jeitA, aim lud.-x* \wicn uo not l>ut -ao 01 primary vaiue.to tna annual, Aims pnospnates oj cal/cium, whuh are tlie cllier lertilizers used tor. lVnv sous, are nigniy eitcctivc in .ncreastug production and ; quality 01 pasture; and as these pnospliates: lUt an important ammai requirement it uas become the fixed practice to g-vc aucn pnospnates tlirougn the grass to the animal, so initiating a beneficent cycle of improvement on the farm, rt"nich finds immediate response in the well-being of pasturct and animal. Should, However, droughty soil eruditions occur as the result of an abnormally dry season (or it may be even the normal drought of summei is responsible but not recognized as an adverse factor) the pasture is liable to assimilate an excess of/ phosphate from the soil required by the animal, which: suffers from mmei.li hunger, resulting in diminished p.'oI duction. If the starvation bc< prolonged or unusually severe in the . asc of phosphate-starvation, symptoms ot malnutrition develop, jUig- animal shows a craving for bones etc., and ultimately becomes lame. It is then that remedies are first sought by the farmer, and the quickest relief is afforded bv drenching- the animal with some .soluble phosphate, preferably (as originally demonstrated by Dr. C- |. Reakes) with syrup of phosphate oi iron. ~11 i A striking instance ol the close dependence of the nutritive value of pasture on. rainfall was given in the last number of this journal. In the I Wairarapa, largely an inland distr.ct j surrounded 'by ./mountain:*, meteo.oI logical conditions vary considerably from year to year, so that in tfirje consecutive summers the phosphoric acid content, of the pasture varied correspondinglv with the changing amount of rainfall. As the nitrogen and therefore the protein content varies roughb with the! phosphoric acid content, it I will be seen that the nutritive value oi a given weight of summer pasture is largely dependent on the rainfall. ]'he lesson to be learnt from this truth is that a soil which in wcs sum mers produces pasture: with a lan amount of phosphoric acid may in dry summers provide insufficient to keep the production up to normal, and the nutritive value of the pasture may ialJ to a figure for protein one-half ol that provided in a wet summer. The remedy for mineral deficiency is simple enough, and there is a longseries of experiments in drought stricken lands to point the way. When the animal is unable to obtain. <ufficient phosphate from the pasture the obvious treatment is to • give phosphates as a lick mixed with salt direct to the animal. There is evidence to show that of all phosphates bonedust is that from which thei elements are most readily absorbed by the animal. Any excess not utilised passes thro.igh the digestive system and is voided n the pasture, so that nothing is wasted. As an insurance, therefore, lowered production due to phosphate hunger in droughty or abnormal seasons, or pliospnate deficiency in the diet duo to any other cause, the use, of bonedust mixed with an equal weight of salt is recommended. Bonedust supplies both lime and phosphoric acid. In the event, therefore, oi calcium, being deficient in the foodsupply, bonedust may also supply th*s deficiency. If the animal gets low enough in condition, however, inedi.;.n----a-l drenching- is the appropriate remedy, as above stated. Recent developments in bujsh-siok districts have shown the very great value of animal licks to supply iron deficient irt the pasture direct to sheep and cattle. lodine has been successfully used in lick form in the iodinedeficient districts of Lake Wauaica. Salt is universally recognised as a necessity for farm stock whereycr the

best results arc desired. The extension of tho salt; lick method to include phosphate is a logical development, and one which, will overcome phosphate hunger caused by seasonal or abnormal droughts,: which occurs in spite oi" top-dressing the pasture. The writer looks to the stock-lick to effect a great step forward in the pastoral development of this Dominion, and this method of improvement is all the more attractive owing to the comparatively low c/ntailed.