Topdressing in Auckland Province

New Zealand Journal of Agriculture, Volume 59, Issue 6, 15 December 1939, Page 493

Topdressing in Auckland Province

Procedure Adopted in Laying Down Experiments to Measure Responses

Contributed by the FIELDS DIVISION, AUCKLAND

.I|||_|||| —l|||—_||||_|||| —|||| —l|||~—~||||—~—l||| ——l||| —.||||—. ||«£< j 1 ' ( This is the first of a series of j 1 articles on topdressing practice j 1 in various parts of the Auckland | I Province. The articles will be ? j written by the Instructors in ? | Agriculture for the districts, = j and will contain definite recom- 1 I mendations for the various soil I j types. At the conclusion of the | » series the findings will be sum- j 1 marised so that the information j I may be on hand in concise f I form. f !.'. , ■ 1 fin—-IHI——IHI-—lift——mi—nn—•mi—

FOR more than forty years pasture topdressing in the Auckland Province has been so' well established as a practice that it would be extremely difficult to visualise what the position would be without this aid to higher production. Manures are undoubtedly a potent factor . in this direction. In fact, it could be claimed with a great deal of truth that the manuring of grassland is by far the most important single factor in the maintenance "of primary production. It is true that other activities, such as the breeding of livestock, the use of better pasture strains, the' practice . of advanced ...ideas . in farm management, and the employment of modern farm machinery are also very important. However, without adequate topdressing, none of these will function to the fullest extent. Good herds will not milk well •' on poor pastures; highyielding pasture strains languish without adequate supplies of fertiliser; and advanced ideas in other directions are of little value without a plentiful supply of stock food, which depends almost entirely upon the efficiency of the manuring of the sward. ' Importance of Topdressing As an indication of the importance of topdressing in the Auckland Province one might cite the fact that of the 3,326,279 acres of grassland topdressed in New Zealand no fewer than 1,707,371 acres (or 51 per cent, of the area) are in the 'Northern Province.

History of Topdressing z . In the very early days of grassland farming very little, fertiliser was used on pastures. ,• Generally speaking, manures were reserved for crops, and pastures were ploughed up when they showed signs of weakening. At a later stage manuring of grassland was

practised to a slight /extent, but with conspicuous success. At this stage the fertilisers used were principally bonedust and basic slag. Gradually the practice increased in popularity, until a fair acreage of grassland in the Waikato was receiving moderate and fairly regular dressings. ' When war broke out in 1914 the cost of bonedust'became prohibitive, while supplies .of basic slag were greatly restricted. Therefore, .attention had to be turned to other sources of fertiliser supplies .which would enable pasture efficiency to be maintained with consequent improvement in production. This was achieved by employing supplies of rack phosphate, which subsequently gave.' way to superphosphate. Undoubtedly, superphosphate • owes much of its early popularity to the fact that other sources of fertiliser supplies were removed. However,, it has proved by its suitability for many northern soils that it is a highly efficient manure. Production has increased enormously, and it has been employed quite freely for cropping ae well as for pasture topdressing.

It is not intended, however, to dwell on the merits of ' any particular fertilisers in this article, but rather.to indicate the procedure that has been adopted in laying down experiments with a view to measuring responses to fertilisers. S Need for Experiments One is very often asked by farmers, “What manure should I use?” It would be very pleasant if, through having the soil analysed, one could immediately name the manure and the quantity that would give maximum returns, but unfortunately soil analysis is practically useless as a guide to, topdressing. The most satisfactory way, and, to the farmer, the most conclusive way, of answering this question is actually to use a series of manures and manure mixtures under the conditions of soil, climate and pasture that the farmer will be placed, and to study the results carefully. Realising this, the Department of Agriculture has carried out extensive trial work with topdressing during past years, and in the Auckland Province alone has 185 top dressing trials at the present time. These are in addition to those connected with pasture mixtures, fodder crops, root crops, etc. J’ Selection of Areas In the Auckland Province there is a wide range of soil types. Heavy clays, light sandy soils, old volcanic areas, river silts, and young pumice soils are but a few of the variations met with in a survey of the province. Just as the soil type varies, so do we find that the responses to fertilisers show a wide diversity of results. Consequently, great care is necessary in choosing sites for trials in order to make certain, firstly, that a trial is

situated; on a single .soil type, and secondly, that it is on a particular soil which is fairly well represented in that locality. . For instance, . if the main soil type was a heavy clay it would be quite inadvisable to select a light sandy type for the experiment. Technique in Laying Down Trials . Notwithstanding the fact that considerable care is exercised in choosing areas for manurial experiments, there is always a possibility that some . lack of .uniformity might lead to a false result being obtained. For this reason all experimendts are laid down in duplicate. Results on one area may then be confirmed on the corresponding second area,, while, if there is any marked variation between the two series,,steps can be taken to ascertain what the cause might be. . Normally this . will be a variation in soil type that was not detected at the outset. After selection of an area the two trial : blocks are pegged according to 1 the number and types of fertiliser under trial. While the general plan will vary according to these factors, a common layout is as follows: Each of .these areas is surrounded

by a “control” strip, which is not manured. Thus, in addition to comparing dressings-with one another, it is possible to assess the response that has been obtained over pasture that has not been topdressed. Applications of Fertilisers When , each trial is laid down it receives dressings of fertiliser in the following quantities: — Carbonate of lime . . 20 cwt per acre Phosphate ‘i... . ' 3 cwt per acre 30% potash salts .... 2cwt per acre In succeeding yearsand each , trial is conducted for at least three or four yearsthe dressing, of lime is reduced to scwt per acre. Dressings of phosphate and potash are continued .at the same rates as for the initial dressings. Recording Results At regular quarterly intervals every trial is visited, when observations are

made on the general management of the field, the type of sward and stage of growth, climatic conditions, and the individual responses of plots to the various . treatments given. For the purpose of obtaining some uniformity in reports the following scale of pointing has been adopted for all manurial trials: — No response over ; no manure . . 0 Doubtful response over no manure ? Slight response over no- manure 1 ■i _ . . J • ' :I ■ Fair response over no manure . . 2 Good response over no manure .. 3 Very good response over no manure 4 Excellent response over no manure 5 Where responses appear to lie between any two of these limits, halfpoints are used to indicate the fact. Thus, 21 would indicate that the response was between fair and good.

In all . reports the standard plot is the “no-manure” strip. This may be open, and weedy, or it may be a fair to good ryegrass-cocksfoot-white clover sward. Differences between this strip and the manured, plot, however, are the features that are pointed and not the general inferiority or superiority of the sward for production of stock feed. Figs. 1 and 2 show an example of improvement to the “V. Good” stage on a poor sward, while Figs. 3 and 4 show the same improvement on a better sward. . . In a series of succeeding articles the findings from topdressing trials in various parts of the province will .be dealt with in some detail. These articles will be written by the Instructors in Agriculture for the districts, and will contain' definite recommendations for the various soil types in their respective districts. When .' all the articles have been published a summary of the findings . will be written so that the information may be on hand in concise form. (To be continued) ~

Grass Seed Mixture for Area Being Cleared of Manuka.

'‘SCRUBCUTTER” (MARTON):— ■ I am now cutting a patch of approximately 30 acres of heavy manuka varying up to 30 ft. high and 4 to 5 inches in diameter. The gully is not steep, and had slipped fairly considerably before the scrub got away at least 25 years ago. It lies partly to . the sun and partly away. - It was originally heavy bush, hinau, rata, maire, rimu, and supplejacks. 1 , What grass seed mixture would you recommend me to sow and at what rate per acre? I intend to burn the scrub and topdress the area with 3 cwt. 44/46 super in early March. 1 FIELDS DIVISION:— I note that it is your intention to topdress the area at the time of seed-

ing, and recommend the following mixture:— '. Government certified perennial ryegrass,’ 12 . lb.; Government certified cocksfoot, 8 lb.; crested dogstail, 3 lb.; browntop, 1 lb; Government certified white clover, 1 lb.; subterranean clover t (Mount Barker), 2 lb.; Italian ryegrass, 3 lb. Total per acre, 30 lb. ' For the shady faces (if these are at. all extensive), the .addition of J lb. of lotus major in place of up to 1 lb. of the subterranean clover is recommended, as the lotus major does particularly well on damp and shady slopes, while the subterranean clover will do better on the sunny faces. 1 . New Zealand’s requirements of subterranean clover will, it is anticipated, be met without difficulty by importations and the expanding local seed production. ,

Slag I+ Lime B’+’g Slag + Potash Lime + Lime . Slag + . Super 4- ‘ PotashPotash + Lime . - -f- Lime Super +Potash Potash + Lime Lime 1 Potash Lime Slag Super Slag 4Potash 'Super.Potash Potash