IMPROVEMENT OF POOR PASTURE.

New Zealand Journal of Agriculture, Volume XVIII, Issue 1, 20 January 1919, Page 15

IMPROVEMENT OF POOR PASTURE.

INVESTIGATION AT WALLACEVILLE LABORATORY FARM.

By

B.C. ASTON, F.I.C.

Chemist to the Department.

INTRODUCTION.

Previous experiments on the improvement of poor sheep-pasture effected by top-dressing with various ' substances, and judged in the main by the live-weight increase of the animals grazed and the carryingcapacity of the pasture, and to a lesser degree by the yield and improved composition of the pasture, were initiated in England . in 1896 and carried on for several years. The chief seat of these was at Cockle Park, a farm on the Duke of Portland’s estate near Morpeth, Northumberland. The land is naturally poor, being valued in the natural state at 5s. per acre per annum.

The analysis of the unmanured soil from Cockle Park showed : Nitrogen, o-2 per cent. ; total phosphoric acid (P 2 O 5 ), 0-07 per Cent. ; phosphoric acid soluble in i-per-cent. citric acid, 0-005 P er cent. ; total potash (K 2 O), 0-50 per cent.; potash soluble in 1-per-cent, citric acid, 0-013 per cent. ; total lime, 0-70 per cent.

Dr. Summerville, the initiator of the Cockle Park experiments, considers that this represents a perfectly normal soil,. rather rich than otherwise in nitrogen and potash, but deficient in “ available ” phosphoric acid and rather low in lime. The “ lime-requirement ” method was not in use when the analysis of the Cockle Park soils was made, but a comparison of the other figures with the Wallaceville soil can be made, from which it will be seen that the Wallaceville soil is much richer in total nitrogen than that of Cockle Park, but is about the same in phosphoric-acid content (" available ” and total), and, like that of Cockle Park, it contains plenty of potash (total and “ available ”), but is poorer than the Cockle Park soil in total lime. It is also to be' noted that in the Cockle Park experiments the addition of 4 tons of quicklime produced no appreciable results on that soil, a strong boulder-clay -situated at 300 ft. altitude, overlying the Millstone ■ grit of the Carboniferous system. The land has been down in grass for some forty years, and was certainly not worth more than 5s. per acre per annum in the unimproved —some farmers even said not more than 2s. 6d. .

Contrary to what is found in New Zealand, burnt lime at 4 tons per acre was practically without effect at Cockle Park, even when repeated in the eleventh season. It became evident as time went on that it was hopeless to expect any profit from the use of this substance, and in the fifteenth season since the first dose of lime was applied its position is practically as hopeless as ever. When, however, smaller amounts of lime were applied in conjunction with phosphatic manures the

addition has sometimes been justified.' The botanical analysis of the hay of the limed plot at Cockle Park showed that in the third season after the application, although the percentage of poorer . grasses (Agrostis sp.) had been much decreased and the percentage of good grassescrested dogstail and cocksfoot —much increased, there was no increase in the white clover ; whereas on the phosphate plots there was considerable increase, in the white clover. .

..The carrying-capacity of the. untreated Cockle Park land for the twenty weeks’ grazing season was 2 sheep to the acre, which was increased to 4 sheep on the slagged and 2-7 on the superphosphatedressed plots. The average live-weightgain per head of the sheep on the unmanured plot was 14 lb. for the first and 24 lb. for the second season’s grazing respectively, lasting from sixteen to twenty weeks. 7 Previous experiments in New Zealand on the improvement of pasture on the lines of the Cockle Park experiments have been attempted at Moumahaki and Ruakura • Experimental Farms (see Department’s Annual Report, 1909, p. 390, and Journal, July, 1914, p. 39). These pastures, whatever it may have been originally, was hardly what could be called poor sheep-pasture, the unmanured plot at the former station carrying 5| and at the latter over 10 sheep on the average, and the top-dressing only increasing the carrying-capacity by about 1 sheep. Mr. A. H. Russell (now Brigadier-General Sir A. H. Russell), at Tunanui, Hawke’s Bay, in 1910 increased the carrying-capacity of 130 acres from 1-24 sheep to 2-07 sheep to the acre by manuring with 2 cwt. superphosphate and 2 cwt. bone-and-blood - manure per acre, increasing at the same time the percentage of lambs and the quality of the wool, at a cost of £1 10s. per acre for fertilizer and distribution expenses {Journal, p. 352, 15/4/11). .

Mr. G. L. Marshall, of Greenbank, Marton, in 1910 top-dressed a 5-acre paddock with a little under 1 cwt. per acre of basic slag, and estimated the carrying-capacity of the slagged paddock as 5-32 sheep, as against 2-98 sheep on an untreated paddock of same size (Journal, April, 1911, p. 218). It will be seen in the foregoing experiments that these lands, judged by their carrying-capacity, are all of much greater value than the Wallaceville land, - and. that even the poor Cockle Park land will carry during its comparatively short grazing season nearly half a sheep more on the untreated pasture than that of Wallaceville, which in a favourable season will carry only i.-6 sheep per acre. On the limestone-dressed paddock at a cost of 15s., and on the limestone and phosphate paddock at a cost of £1 19s. 6d., per acre for fertilizers, however, since 1st November last nearly 5 sheep per acre have been carried, with every prospect of this capacity being maintained for another month or so.

THE WALLACEVILLE EXPERIMENTS

■ - The. experiments here recorded embody' all that has resulted from an extensive experimental scheme of pasture-improvement which, based on the Cockle Park experiments,* was drawn up by the writer in 1914 and- submitted to the Board of Agriculture. The Board

* See “ Influence of Manures on Mutton,” Jour. Board of Agriculture of England, Vol. vi, No. 3, Dec., 1899 ; and Vol. vii, No. 3, 1900 ; and Supplement to same, Vol. xvii, No. 10, Jan., 1911. All articles by Dr. Somerville, Professor of Rural Economy, Oxford University.

approved of the scheme, and • appealed to representative farmers - in various parts of the North Island to carry it out on different types of soil. Although several offers were received, owing to various circumstances it was not possible to do anything further in the matter except at the Wallaceville Laboratory Farm, at which the former Director of the Live-stock Division (Dr. Reakes) - enthusiastically entered into the scheme and gave or obtained all necessary authority for the work* conducted under the writer’s supervision. Mr. J. Evans, Farm Overseer at Wallaceville, has been in direct charge of the experiments, and it is largely due to his keen interest that it has been possible to carry out these experiments in war-time-. . The area selected is of very inferior carrying-capacity in the unimproved condition, and as it represents a. considerable area of similar land it is a suitable site for experiments of this nature.

SOME ACCOUNT OF THE SOIL AND ORIGINAL VEGETATION

The soils of the Laboratory . Farm, which adjoins Trentham Racecourse, are situated on the Upper Hutt gravel plain, the subsoil of which, : to a depth of many feet, always consists of boulders and gravel mixed with a smaller amount of finer material, sand, and- clay. Some . idea of the mechanical composition of the subsoil may be gathered . from the analyses-of the adjoining Trentham Camp soils analysed in August, 1915.

Geologists consider that these gravel-boulder beds are not those of an ancient lake, but that the area they occupy was a rock basin gradually formed in the Hutt Valley by faulting and warping, and which the Hutt 'River filled with boulders, gravel, and finer material as fast as the basin was formed. This possibly accounts for the . fact ’ that large boulders are often found near the surface. The depth of soil above the gravel is very shallow, sometimes not more than i|in., but usually from 4 in. to 9 in. The effect of such a porous subsoil so near the. surface is that the soil tends to dry up rapidly in the summer, and is dependent mostly on the summer rains and dew for the supply of water necessary to keep a grass-covering alive. On the shallower soils of the farm, such as those of paddocks Nos. 1 to 5 (which - have never been ploughed since the forest was destroyed, . and are very uneven in surface, as all forest soils are before ploughing), the grass which is the dominant constituent of the pasture is Danthonia pilosa, a highly drought-resisting native "grass and eminently fitted to survive on the shallow dry soils of this area. The forest, which has been destroyed, was undoubtedly the black-birch (Fagus Solandri), which still exists

in the vicinity, . mixed with a little maire (Olea Gunninghamii), pokaka (Eleocarpus Hookerianus), black-pine or matai (Podocarpus spicatus), and totara (Podocarpus totara). In some places this shapely tree has been allowed to remain in the paddocks, and might- mislead the observer into thinking that totara was perhaps an important constituent of the beech forest, but this was not so —at all events within recent times. The undergrowth of the forest consists chiefly of various shrubs ; species of Coprosma — C.. rotundifolia, C. rhamnoides, C. crassifolia, C. areolata, C. parviflora, C. propinqua, C. robusta, C. Cunninghamii ; and. Carpodetus serratus, Leucopogon fasciculatus, Myrtus pedunculata, M. bullata, Melicytus ramiflorus, M. micranthus, Myrsine Urvillei, Pittosporum tenuifolium, Panax anomalum, P. arbor Melicope simplex, and the giant sedge Gahnia zanthocarpa, . and the climbing plants Clematis indivisa, Muehlenbeckia australis, and Parsonsia heterophylla. ' ■ ■

G/247: Sampled 26/7/15 in three places to a depth of 3 in. to 5 in. on danthonia pasture, unploughed. . ■ H/405 : Forest soil sampled in several places in Fagus forest adjoining the virgin danthonia pasture, 22/11/16. K/455 : Sampled 12/11/18 in about six places to a depth of 6 in. to pin. on No. 2 paddock, unmanured. K/456 : Sampled 12/11/18 in several places on No. 3 paddock, manured with phosphate and limestone. . -

A mechanical analysis of sample H/405 showed, — Per Cent. ' Per Cent. Coarse sand . . .. ■ ... 11-4 Fine silt .. .. .. ro-6 Fine sand . .. .... 22-5 Clay ' . . . ' .. ... Nil. Silt . ' . . . . . . 24-1 Moisture, organic matter, &c. . . 29-6

The results show the soil to be a sandy silt, fairly well supplied with total potash and nitrogen and available potash, but deficient in available phosphoric acid. The excess of magnesia which is often found in birch or beech (Fagus) country supports the view that liming with limestone would be-beneficial, and the lowness of the total and available phosphoric acid compared with the. excessive amount of potash suggests that phosphate in conjunction with limestone would be the appropriate manurial treatment.

* See parliamentary paper H.-29A, Report of - Department of Agriculture, 1915-16, page 5. ■ ‘ •

Stones and boulders (above G/257. % G/258. /o 0/ G/258. 0/ . /o —Laboratory Number.G/259. G/260. ’ G/261. G/262. % % Laboratory Number.G/262.G/272. 0/0/ - /o /o G/272. • G/273. % % G/273- % % G/260. °/ /o G/26T. % /o 24'8 32’1 42-5 48'0 39'0 12 mm. diam.) ' Gravel (2-12 mm. diam.) 19-1 7’9 5’9 . 5'4 • 3’7 4'0 19*0 19’0' Fine earth (below 2 mm. diam.) 56’1 ■ Go'o 51’6 94’6 96’3 96’0 33’0 42*0 — • — — — .— — — — ■ 100*0 100*0 100*0 100*0 100’0 100*0 100’0 100*0 Locality No. .. I ■■ 2 3 I * 2 3 3 ■- I A —— ~Y " _____) — -y- ! V , ) First foot, including top Top few inches analysed Second and ■ few inches. separately. third feet.

G/247H/405. K/455. ■ . K/456. Moisture '. . . . . . . . 10-24 9-49 ' 8-55 10-72 ' Loss on ignition * .. . . .. 14*75 . 19-15 11-72 10-99 Nitrogen . . . . . . . . 0-366 o*47 .. Hydrochloric-acid extract— ' Potash (K 2 O). . . .. ... 0-320 0-31 0-42 0-50 • Phosphoric acid (P 2 O 5 ) • • • • 0-078 0-08 0-06 0-09 Lime (CaO) .. .. .. 0-407 o-33 0-42 o-68 ■ Magnesia (MgO) ’ . . . . ... 0-444 0-38 0-70 0-75 Citric-acid extract— Potash (K 2 O) .. ( . . . . . . 0-057 0-040 0-030 0-037 Phosphoric acid (P 2 O 5 ) . . . . 0-007 ■ 0-014 0-006 0-009 Lime requirement (Hutchinson - MacLennan method), per cent. (CaCO 3 ) .... .. o-57 0-25 0-06 : ’The results (except for ," moisture ” and “ lime requirement ”) are percentages on soil dried at too 0 C. - ”) are percentages Description of Samples.

The analyses of virgin and unploughed soils from the Wallaceville Farm are as follows