CROP FAILURES

Wanganui Chronicle, Volume 79, Issue 280, 26 November 1936, Page 5

CROP FAILURES

SOME OF THE CAUSES RESULTS OF RECENT RESEARCH. (Address broadcast from Station IYA Auckland, by W. Alexander, Agricultural Adviser, Kempthorne Prosser and Co.’s N.Z. Drug Co. Ltd.) There is probably nothing more exasperat.ng to a farmer or gardener than the failure of a crop that has been sown with elaborate care and at considerable cost. There are crop failures due to seasonal conditions such as droughts or floods, or to attacks by insect pests etc., that are so perfectly obvious as to leave no doubt at all concerning the cause, but there are many other failures where the loss may be just as great but the cause more obscure. It is not always possible to ascribe the failure of a crop to any one factor; it frequently happens that there is a combination of factors responsible and the difficulty is to place these in their proper order of importance. Drainage. One of the commonest causes of crop failure is bad drainage. The dif ference between good drainage and bad is equal to the difference between a good climate and a bad one—it may even be equal to the difference between a hot-house and a cold-frame. It is recognised that by draining one can raise the soil temperature by as much as 10 degrees and that 10 degrees makes a mighty difference at certain seasons of the year. Soil fertility depends greatly upon the activity of soil bacteria and this activity in turn is influenced by drainage. Soil that lies waterlogged throughout winter and into the spr.ng does not provide a suitable habitat for soil organisms of a helpful nature. Such soil may teem with bacteria but they will be of a type that tolerates or even creates activity, and as such are not helpful. Some soils have excellent natural drainage, and on these, crop failures could not be due to faulty drainage. But there are extensive areas of badly drained land where crop failures are common. I recently had the experience of seeing several herds of dairy cows on adjoining farms wading about up to their hocks in mud on alleged grass paddocks in September. That there was any grass at all in these paddocks under the condition they were in, speaks volumes for the owners concerned, but even then the grass itself was at least a partial failure in that it was not good enough in quality to produce a satisfactory yield of but-ter-fat. An interesting condition arising out of natural drainage was observed recently in the Bay of Plenty. Light pumice country at an altitude of nearly 1000 feet above sea level showed quite an appreciable spring growth some weeks ahead of heavier and r.cher land situated near the sea coast. The Lime Position. “Although no precise information is available, it is extremely probable that next to drainage, no single cause is more seriously limiting crop production—and also render.ng uneconomic any increased expenditure on manures—than is soil acidity.’’ (Journal of Ministry of Agriculture). Instances of failure, apparently due to excessive soil acidity pr calcium deficiency, are of common occurrence. Certain crops will tolerate fairly acid conditions, but others again simply fail to grow where the lime content of the soil is below a certain level. It is commonly known that lucerne, for instance, will not succeed on sour soils. Root crops will tolerate a certain amount of acidity, but when asked to do so they usually have to struggle against excessive weed growth and the outcome of the struggle is a low-yield-ing crop of roots. A deficiency of lime in the soil makes for unfavourable conditions for soil bacteria, particularly the bacteria responsible tor the collection of atmospheric nitrogen. Clovers that work to such advantage in the building up of soil fertility never do really well on sour soil and no doubt the main reason lies in the unfavourable conditions for the clover bacteria. Deficiency of l.me in the soil has a decided limiting influence on fertilisers—particularly superphosphate—and in this way alone may be primarily responsible for many crop failures. Again there is always a tendency for lime-defic.ent soils to get into very bad physical condition so that they are difficult to work and, moreover, they make so poor a job of handling moisture that they are too wet during the wet weather and too dry during the dry weather. You may incline to the opinion that the control of soil moisture is a drainage job and has nothing to do w.th liming. Certainly drainage comes prominently into the picture, but not so prominently as to exclude the influence of lime. Lime will act beneficially on soil texture from the surface down to the more or less permanent water-table and whether that io a matter of one foot or six feet is a matter of drainage. Phosphate Deficiency. 1.1 an English Agricultural Journal of it cent date we read that "after 100 yea r s of artific.al phosphate fertilisers, phosphate deficiency is still an important cause of crop failure.” We have not had 100 years’ experience uith artificial phosphatic fertilisers in New Zealand, but we have had more than 50 years, and like our kinsmen overseas we can say here that many crops fail through lack of phosphate. Such failures are, in the main, associated with the more acid soils. Actually the term “crop failure” in this case is just a little bit misleading, in that crops grown with insufficient phosphates are inclined to be small and stunted and of poor quality, rather than a complete failure. In most cases, grass is the crop being grown on phosphate-deficient soils. That follows from the facts that most New Zealand soils are naturally deficient in phosphates and also" that most of the land in occupation is in gcass. In some cases the grass crops look good; in fact, I have seen what looked like really first-class pastures on land that was most disappointing from a production point of view. The only explanation of this anomaly is that a shortage of phosphate, or it may be calcium, is responsible for the production of poor quality feed. In other cases the pasture is definitely poor both in appearance and in production where the supply of “available” phosphate is limited. This particular condition is common throughout the pumice belt where experience has proved most conclusively that satis-

factory pasture establishment is impossible without a liberal application ot phosphatic fertiliser. A common cause of crop failure is < lack of balance in the supply of plant food. A chain, as you know, is just . as strong as its weakest link, and it is quite in order to say that many elements used by the plant for its sustenance are just links in a chain that I is strong only when these many elements are correctly balanced, in the I case of some elements, plants require only minute doses, yet it such minule | doses are not availaole, failure results. 1 Where the ratio of available phosphate to available potash is in the 1 vicinity of 10 to 1, the conditions for 1 many crops are adverse, and trouble in one form or another is encountered, a very high phosphate level associated with a low potash level spells failure. In this investigation we have further proof of the statement that an excess : supply of phosphates will not make good a deficiency of potash. From another authorative source we are informed that plants, particularly cf’tais, that are starved for potash will take up nitrogen in excess of requirements and store it in the grain Lg the great detriment of qual- 1 rty. ' These examples of crop failures are 1 not apparent to the casual observer, but they are of very great economic importance and are quoted here so ■ that I might impress upon you the ■ fact that tnere are failures that might 1 almost look like success until we apply ; the cold and calculat.ng measure of ■ profits to them. Insufficient Cultivation. Cultivation plays an important part . in the production of crops of all kinds < and a great many crop failures can be , traced to faults in the methods adopted. Late ploughing is a common fault. In the preparation of land for ■ root crops, it is important that the prelim.nary work be put in hand early. Old pastures that are to be . broken up should be ploughed during the winter months so that the sweet- , ening or mellowing influences of the , weather, and particularly frosty weather, may be allowed full sway. Subsequent cultivation should be such j as to kill as many weeds as possible, ( and also to secure that measure of consolidation that will bring about ] early germination and a rapid estab- | lishment of the young plants. Later ploughing and hurried cultivation miss d these very essential points. < There are probably more pasture , failures of one sort or another than ( there are amongst all other classes of f crops put together. Again that is be- , cause the bulk of our occupied land is . in grass. We see failures in the estab- , lishment of young grass and we see : failures in the response made by older ‘ pastures to fert.Users. All grass , species are not alike in their capacity ! for making use of artificial fertilisers. ( It takes something more than manure to make certain pasture species ; change their normal season of productivity. For instance, it seems to be a matter of impossibility to make cocksfoot come away early in the spring or to make paspalum grow through the winter. Nearly every call made in response to a complaint regarding the failure of fertilisers on grassland discloses the fact that the pastures concerned lacked ryegrass. Time after time do we come across the same old story of a heavy autumn topdressing failing to bring the grass away in the spring, and always the sequel is the same—a poor type of pasture lacking in ryegrass and white clover. Topdressing such species as browntop, Yorkshire Fog, Sweet Vernai, Fescue, etc., may make these species more palatable and nutritious than they would otherwise be, but it will not make them come away for early spring feed. Many of these poor pastures were sown down before we really understood that a difference existed between the various strains of ryegrass and clovers, but a good many have been sown down since and still the poor types of rye are being used.

- It is just so much wasted effort to go 1 to all the trouble that is involved in the preparation of land for perman- » ent pasture if you are going to sow int ferior strains of rye grass and white t clover. To-day a farmer can purchase s pedigree seeds with as much certainty ' as he can buy pedigree stock and it is ■ false economy not to do so. t Type of Fertilisers Used. a There is just one other cause of crop 3 (failure that I would deal with now, [ 'and that concerns the choice of fer- f tilisers. This Dominion uses round I e about 450,000 tons of fertiliser annu- v r ally, and of that amount an unknown ii e percentage fails to produce results L that can be regarded as satisfactory, ti j There may be several reasons for this; t< it may be bad drainage, want of lime F. in the soil, poor pastures or even bad p s seasons, but there is also another con- b e tributory reason and that is using the a wrong type of fertiliser. By the t e "wrong type” 1 mean something like _ this:—(l) using super alone on sour I r land, especially peaty country. Many C s North Island soils have a very low pH c a value, disclosing a lime requirement of s< “ 6 or 8 tons of carbonate of lime per a acre. Where that is the case, super e 2 alone may be only 50 per cent, eftecr tive, whereas when used along with a lime it will pull its full weight, which n j is much better. (2) Leaving out S a potash where this particular food is I t known to be in short supply. In the 1 , N.Z. Journal of Agriculture for July, k f 1934, Messrs. W. J. McCulloch and J. r M. Smith, reporting on the results of t some topdressing trials laid down in q Taranaki, state that "in Taranaki to- p day the use of potash is as important t t as that of phosphate.” Super alone has ? s given a good response, as can be gath- f 2 ered from the further statement, by v s the same wr.ters, to the effect that k 1 phosphates alone changed a poor or a r fair sward to a good one, but tne addi- s s tion of potash changed that good one t I to an extremely good one. (3) Using c e a slow-acting form of plant-foou f ? where all the conditions demand a d * quick-acting one. The Department of e Agriculture makes no mistake in ad- k Y vocating a more general use of super- f '• phosphate as against any other form s II |of phosphatic plant-food. All the h ! > other forms on the market have been q tried out under varying conditions, p t I but no one of them has proved to be a ‘ better than super, or super plus 1 me. t e I In the N.Z. Journal of Agriculture for t s I April, 1935, Mr. P. W. Smallfield, fields o superintendent for the Auckland pro- '1 e vince, sums up the result of six years v 1 of pasture topdressing trials in his c f territory with these words: “Super- f " phosphate is generally the cheapest v s and most efficient phosphate for pas- e ’ ture topdressing, but on some soils v e lime is necessary to enable the best 1 r results to be obtained from super- n s phosphate. Slag is also qu te efficient, p< y but is not superior to superphosphate, 1 ’• or superphosphate and lime. Rock b e phosphates are generally inferior to c s superphosphate or slag.” !- = ■■ —~ (