FARMING

Rotorua Morning Post, Volume 2, Issue 558, 15 June 1933, Page 2

FARMING

SOIL AClDITY V t 1 « -4 - * * V \ \ l .& "V >. • 7 PRODUCTION INOREASES-NOT ALWAYS RECORDED BY WEIGHING MACHINE. In. the course of an articl'e on rna'nures, Mr. W. Alexander, Agricultural Adivser, Kemp'thorne, Prosser and. Co;., Ltd., says:— My talk to' you to-riiigiht , ■ is an attempt on my part to correct some wrorig impressions that unfortunately are all itoo widely held hy farmers throughout the Dominion. It is my privilege to come 'into .close contact with a large number of farmers . in the course of my travelling round the country, consequently I have somewhat unique: opportunities of coming face to face with all kinds of wrong impressions, some of which are of a serious nature. and some of which axe not so. At the moment I am goinig to deal with only a few of the more serious of these wrong impressions and in doing so I want to take this opportunity of saying that in these broadcast talks, as )in our everyday work, we only want to be helpful to those on the land and that if our criticism is at times somewhat severe it is offered in a helpful spirit. The wrong impressions ahout which I >am going to spieak to-night apply to the use1 of fertilisers, and1 I think it is quite appropriate to the season of the year and the state of agriculture generally that this. talk should be given. In the first place it is wrong to assume that unbala.nced fertilisers can succeed in maintaining fer-. tility in the soil. Just imagine the final result of taking out of the soil some ten or twelve separate elements ■of fertility and of putting hack only one or two. The most commonly held "wrong impression" is that phosphates alone will supply all the requirements of live stock; this impression is more particularly .wrong in so far as dairying stock are concerned. It is quite true that the universal need in the soils of New Zealand is phosphate, but .it is not correct to say or think that it is phosphates only. Stock Troubles. We have the indisputahle evidence of an almost universal concentration on phosphatic manuring being accom1 panied- by a seriously increasing amount of stock trouble. If phosphates alone was all that we required then we should not have nearly so much niortality amongst the fl'ocks and herds.- In all our manurial work we have been too much inclined to take the shortsighted view of results and consequently adopt that practice, which, as it (were, speaks loudest. Let me illustrate -a. little more clearly: Experiments laid down throughout New Zealand demonstrate the fact that where super is used as a top-dressing on pasture or as a fertiliser for crops, the increased growth resulting can he detected by the eye and can actually be measured over the scal'es — in other words the results are obvious. At the same time other fertilisers used lin the 'experiments may have, on first application, resulted in merely improving the quality of the pasture or the crop, but because such a result is not visible to the eye nor .can it he measured over the scale, its -significance is apt to he overloolced. The shortsighted interpretation of the results of such expeifments says that supei* is the correct fertiliser to use all the time, but the more reasoned .interpretation says that live stock or crops remove from the soil plant foods other than those supplied by super, consequently, if I am going to maintain fertility I must put these other I plant foods in also. ■ Super Responsible. Another widely held "wrong impression" is that super iis. largely responsible forj many of the stock troubles experienced by farmers to-day. This impression is a more or less natural successor to th'e impression that "super alone" is all-sufficient . as a fertiliser. Because a man has used practxally nothing else for top-dress-ing his pastures, he will argue that it must he the super that causes his cows to slip or his heifers to fail to breed. It is so,metirnes difficult to get this man to realise that it is not the presence of super, but the absence of some other essential mineral that is. the root cause of his troubles. Super as turned out by modern factories is a perfectly 'harmless product as far s its eqffect on the health of stock is concerned. I have often seen super used in a lick mixture and have both recommended its use and used it to feed to stock suffering from such bone diiseases as osteomalacia and ricketts. There is no doubting the1 fact that there is a relationship hetween the use of super and the incidence of sterility or ahortion,( hut^ that( relationship is i*i no way detrimental .to super. The use of super has resulted in pasture, improvement which in turn has made the carrying of more stock possible and thiis increased carrying capacity has demanded a igreater supply of all min'erals — tnot only those available in super — with the result that nature's supply is insufficient to meet the greater demand, and the high-produc-ing animal suifers. The_ actual truth of th'e matter is that the continued use of super has made the application of calcium or potash or hoth an essential factor in maintaining productivity and the health of live stock. , . . . Soil Acidity. From. a .somewhat different source has emanated the "wrong impression" that super-. causes the soil to beeome. sour and acid. This is not so much' a farm'er's idea as. an idea started and rejuvenated every nowj, and then by other interests, The suggestion that super creates soil acidity -has circulated throughout the .-world in every' country where sup'erphosphate ffis tised; and this very isuggestioh; unsupported as it is, or ever -bas- beenj hy any; scientific or practical evidence^ 'has

been responsible for some most valuable res'earch and' experimental work. ' In a recent article dealing ■ with this very question, a French scientist goes minutely into the details of . experiments carried. out in different pa.rts •of the world and for th'e1 information' of readers shows how it is utterly im-. possible for sup'erphosphate ,as We know it to .increase the acidity of the. soil to which it may be applied.. Looked at from the point of view of the farmers, -it is obvious that he must he careful — particularly in the present economic circumstances — to employ fertilisers which have not only established a reputation for in-. creasing the yield of crops, but which have been proved to he innocuous both to the physical constitution of the soil and to what it has been agreed to call its "sanitary condition," Which, one cannot too oftenyrepeat, depends strictly upon its reaction. It is th'erefore essential for the agriculturist to know wh'ether the accusations made in this respect against superp'hosphate are actually justified, or whether he' may continue to use this fertiliser as he has done in th'e past. Free Acids. The allegation that sup'erphosphate renders acid cultivated soil or. grasscountry upon which it is used has •arisen from the fact that. this fertiliser has, from the moment of its production, a clearly acid .reaction, which •is shown by its corrosive effect upon the sacks in which it is contained. This chemical reaction is not due, as is sometlmes stated, to free sulphuric acid. The chemically acid reaction of superphosp'h'ate is due, in reality, on f(he one 'hand, to the monocalcium • phosphate, which is its principal ac--tive constituent and which helps to give1 it its great fertilsing value, and on the other hand, to the free phosphoric acid which it always contains in proportions varying from 1 to 6 per cent. Is this acidity of such a nature as to exercise a harmful, action on the soil or on the vegetation? This is the question which' represents itself immediately and naturally to the mind. All the c'hemists to whom this question has been put have immediately replied that it was logicaily impossihle; the reason being, apparently, that in the case of superph'osphate you, have a fertiliser consisting of an /acid — phosphoric acid — and 'a base — sulphate of lime, and that in actual practice the plant absorbs the acid, which is the 1 plant food, and leaves the base, which is .at least neutral, in th'e soil. If the case was just the reverse — tWat is, that th'e base was. the plant food, and the acid was left, then the effect would be to increase the soil acidity. Some fertilisers do work that way but superphosphate is not one of them.