PASTURE TOP-DRESSING EXPERIMENTS AT TE KUITI.

New Zealand Journal of Agriculture, Volume XXIV, Issue 5, 20 May 1922, Page 283

PASTURE TOP-DRESSING EXPERIMENTS AT TE KUITI.

TESTS WITH NAURU ROCK PHOSPHATE.

T. H. PATTERSON,

H.D.A., Instructor in Agriculture, Auckland.

A series of fertilizer top-dressing experiments was started in August last on Mr. Charles Harrison's. farm at Te Kumi, about two miles from Te Kuiti. Mr. Harrison offered an area of permanent pasture which has been laid down at least eight years, and has had no dressings of artificial fertilizer nor lime for the past five years. When the writer inspected the pasture in August it was composed chiefly of cocksfoot, perennial rye-grass, crested dogstail, a little timothy (especially in the depressions), white ■ clover, and suckling- clover or trefoil. The soil is a light loam with only a moderate amount of humus present. The subsoil is free with good capillary powers, as evidenced by the way it stands dry spells. The land, which as far as can be ascertained was originally in bracken-fern, is undulating and is typical of thousands of acres of similar country in the Kingcountry. ■ It is free in nature, easy to work whether wet or dry, and naturally well drained. - The rainfall is an important factor in the efficiency of slow-acting phosphatic fertilizers. Following is the record , for Te Kuiti in 1921, covering the period of the tests here recorded :-

The . rainfall in. January, 1922, was 2'93 in., with fourteen rainy days. The mean annual rainfall for the last ten years (omitting 1919, which is not available) is 60 in.

... A local; committee of . dairy-farmers, including the . owner of the property,. Mr. Harrison, is co-operating with the Department in carrying out the trials. The principal of the District High School is on the committee, in addition to the farmers.

The primary object of the tests (which form part of a scheme of top - dressing experiments in different districts of the Auckland Province and other parts of the Dominion) is to determine the value of finely-ground raw rock phosphate for permanent' pasture. Phosphate from Nauru Island was used on plots side by side with basic slag, while other plots received high-grade superphosphate

manufactured New Zealand from Nauru/Ocean phosphate rock. Control plots receiving no dressing of fertilizer were included as checks. Raw phosphate and superphosphate were also applied to plots which had received dressings of ground limestone immediately previous to the application of those fertilizers. The dimensions of " each plot are 5 chains by two-thirds of a chain, the area being one-third of an acre. The long narrow plot reduces error caused by the varying quality of the soil and other disturbing factors. : The eighteen plots, which allowed of each dressing being in triplicate;? were arranged in two rows of nine each. Some authorities, . after making t careful examination of different systems of arranging plots in field experiments, have found that

this . arrangement gives '■ the most accurate results. v There is a division 3 ft. wide separating individual plots, and a shallow trench made by a plough around each one. This provides to a large extent against the surface washing of fertilizer from one plot to the next. The plots were set out gratuitously by Mr. A. W. Cheal, N.Z.1.5., of Te Kuiti. The fertilizers were applied on Bth and 9th September last. These dates were late for slowly soluble . fertilizers such as raw rock phosphate and basic slag, but this was unavoidable without missing a season, as the offer of the field was only made to the Department in August last. The field was. shut up in October, and cut and weighed as hay in January. The weighing occupied two days, and was completed on 16th January. The following table gives the first season’s results after the grass was made into hay, and the yields thus recorded : .

If the average of the three check plots which received no fertilizer is considered as being free from error, then the natural yield of the pasture is arrived at.' Superphosphate gave an increased yield of over 73 per cent. If io per cent, is allowed for experimental error for the first season’s results, then it still has shown an increase of 63 per cent. over, and above the natural yield. ■ Combined with ground limestone it gave 2 per cent, higher. Basic slag gave an increase of 23 per cent... and rock phosphate over 23 per cent. Allowance may be made here for probable error. The slight difference in favour of the rock phosphate may be negligible, but when farmers are anxious to know how rock phosphates compare with a popular and standard fertilizer like slag it becomes more significant and will be taken notice of. The very high increase from superphosphate was to be expected, as the fertilizers were only applied in the spring, and this unduly favoured the quick-acting superphosphate and handicapped the slower slag and rock phosphate. As in the trials, at Puwera,* lime used with rock phosphate has decreased the. growth. ■ It is intended to top-dress the plots again during the present month, and cut for hay again next summer. In comparison-; with superphosphate the slag and .raw rock phosphate should produce higher yields next season. It is very satisfactory to know that, if the occasion should arise as predicted, the raw rock phosphate will — as results so far indicatemake, a good substitute for high-grade slag,

which was made by the old Bessemer process, now superseded in England by the newer open-hearth method by which a lower-grade slag is produced, with a low solubility. . It is difficult to put the results of these tests on a money basis, as farmers who save hay usually find it indispensable for their own use if they want to carry their -stock through the winter satisfactorily, and do not sell. However, if one assesses it and the fertilizers with cover used by insurance' companies, then the following table will show comparisons of some interest.:

This season the hay in the stack is assessed by insurance companies at £3 per ton, and the fertilizers at 75 per cent, of the then market price at the time of application for cover. The labour in applying the fertilizers, and other factors, are not taken into account in the table. It will be seen that on the very conservative basis used in these valuations it paid, except in the case of the lime and rock phosphate, to cut for hay. When fed to ■ stock the value of the hay is greatly enhanced, and it is difficult to put a price on it.

Te Kuiti ground limestone : 91 per cent, carbonate of lime (C a CO). Wheat and Oats Threshings. — Returns of actual threshings received to 20th April by the Government Statistician from millowners showed that until then 3,266,320 bushels of wheat and 1,544,240 bushels of .oats had been threshed out. The average yields per acre in cases where particulars of areas were furnished (covering 99 per cent, of total threshings) worked out at 30-89 bushels for wheat and 37-67 for oats. Shorthorn Herd-book. — We acknowledge with thanks receipt of a copy of Volume xviii (1922) of the New Zealand Shorthorn Herd-book from the secretary of the Society at Christchurch. Noxious Weeds. — Gorse has been declared under the Noxious Weeds Act by the Hokianga County Council.

* See Journal for December, 19213 page 364

Jan. Feb. Mar. April. May. . June. JulyAug. Sept. Oct. Nov. Dec. Total. 1'97 2'26 1-86 3-67 2'30 Rainfall (Inches). 7-16 | 7-14 | 4-46 | 3-51 10-32 4-65 4’65 I 7'50 | 56-8o 56-80 13 7 9 IO Number 13 I 17 ' of Wet Days. 18 I 14 1 13 s. 13 21 21 14 14 17 17 166 166.

• Fertilizer used. ; Amount per Acre. Yield per Acre: Mean Average' of Three Plots. Percentage Yield. Percentage Increase due to Fertilizer. Cwt. qr. lb. ' Check ’ . . . . No manure 23 2 20 ' . 100'0 Basic slag. . 3 cwt. 29 O 16 : 123-0 ' 23-0 - Superphosphate 3 cwt. ■ 41 O 19 173-8 73-8 ' ■' - Rock phosphate 3 cwt. 29 I 3 123-6 23-6 - Superphosphate 3 cwt. Ground limestone . . ; u 17 i ton 175’9 ) 41 • . 75-9 1 Ground limestone . . T 7 i ton I 75’9 75 9 Rock phosphate 3 cwt. Ground limestone . . 3 cwt: i ton J: 27 - I !7' IT 5-7 \ 15-7 •

Expenditure on Manures. Cash Return as Hay. Gain or Loss. £i on basic slag . . . . . . £ s. d. i i 9 £ s. d. : Gain 019 £i on superphosphate . . . . 3 ii io Gain 2 11 10 £i on rock phosphate 14 5. Gain 045 £1 on superphosphate and lime i 5 9 Gain 059 £i on rock phosphate and lime 0 5 5 Loss 0 14 7

Fertilizer. Total Phosphoric Acid (P2O5). Tricalcic Phosphate. Superphosphate . . . . Per Cent. Per Cent. 22’4i (19-4 soluble in water).. 48-92 Ground Nauru phosphate . . 36’49 (8’o soluble in 2 per cent, citric acid) 79’66 Basic slag . . . . . Per Cent. 22-41 (19-4 soluble in water).. 36-49 (8’o soluble in 2 per cent, citric acid) 19-5 (15-82 soluble in 2 per cent, citric acid) Per Cent. 48-92 79-66 42’57

The report of the Department’s Chemist on the fertilizers and lime used gave the following particulars :