Pasture Establishment

New Zealand Journal of Agriculture, Volume 72, Issue 1, 15 January 1946, Page 71

Pasture Establishment

By

E. M. BATES,

Instructor in Agriculture, Alexandra.

NEW Zealand’s exportable wealth is derived principally from grasslands, and establishment and management of pasture are of vital importance to. the farming industry and the prosperity .of the Dominion. Recent research developments and the outstanding results obtained by isolated farmers under a variety of conditions in different localities give some indication of the potentialities of grassland along sound lines of development.

DUE principally to climate, farming in the North Island of New Zealand differs from farming in the South. The North Island is pre-eminently suited to grassland farming, the South Island to rotational pastures and arable. crops, with the alternative of permanent grasses of comparatively low production. There are, however, some 14,000,000 acres of hill country mainly in native tussock grasses. The North Island grasslands may be divided broadly into two main classes: 1. A relatively small proportion of the total area is capable of holding high-producing permanent species, which in the humid climate have a long seasonal growth range and high carrying capacity. Soils are either naturally fertile or fertility has been built up to ryegrass -white clover standards by highly-efficient management and topdressing. Probably an additional million acres at present dominantly browntop, rushes, sweet vernal, and other weeds are potential ryegrass-white ' clover swards under better exploitation, such as adequate drainage, topdressing, and management.

2. The greater proportion of . the North Island consists of unploughable hill country brought in from forest and scrub. Because of lower fertility, existing pastures are in various transitional stages towards stable associations o f low-producing grasses and clovers. Danthonia and browntop are the dominant species under drier and wetter conditions respectively. A n appreciable change in fertility affects the composition of the sward. Building up fertility for example on a dan-

thonia sward can ; do little to increase the limited growth of this species, but promotes development and dominance of stronger growing, more useful pasture, plants. On light country such a fertility change may follow a good take, of autumn-sown, subterranean clover stimulated by phosphatic topdressing through stock. Frequently better species are surviving in the poorer pastures without making appreciable growth until fertility is raised, but in some cases broadcasting of additional seed may be warranted. Time of Sowing In the more humid districts longrotation and permanent pastures are usually autumn sown. Wet conditions and weed growth make establishment more difficult in. the spring, especially on heavier land. During autumn the ground is drier and warmer, competition from weeds is less, and in the north particularly the relatively mild winter conditions give little check to autumn-sown pasture. Permanent pasture in the North Island ,is frequently sown after oats, a rotation which,

although not ideal, permits early autumn sowing. Following summer forage crops such as rape and turnips a seed-bed often cannot be prepared until towards the end of April. < In districts with ample rain early February sowings may be satisfactory, but they are risky in drier localities. In colder districts the extra, time for , establishment before winter is an advantage. Late Feb-ruary-early March is generally considered the optimum period of sowing in many parts of the Dominion. Short-rotation pastures in arable farming districts of the South Island are generally sown in spring, as they are then more suitably fitted in with annual cover, cash, or fodder crops grown in the rotations. In the cropping districts of the South Island early autumn conditions are usually too dry for good pasture establishment, and in any case the ground is generally occupied with crops at this time. Late-sown pastures on the other hand are liable to severe frost-lift damage and complete failure of clovers. The most satisfactory autumn sowing for long-rotation pasture follows spring ploughing and summer fallowing to conserve moisture and promote a mellow tilth. A partial failure is not uncommon when sowing down after a cereal stubble, when the soil is less fertile, often dried out, and difficult : to cultivate until late in the season before rain softens the hard ground. Sowing For the critical period of pasture establishment conditions must be made as favourable as possible. The seedbed should be fine and firm from top to bottom. On cultivated ground seed

and fertiliser are usually broadcast on a Cambridgerolled surface. A stroke with light grass harrows is sufficient to cover the seed. Broadcasting of permanent pasture seed gives the best ground cover and is general on heavier an d medium lands. On light soil, and especially in dry localities, where the seed-bed is not entirely satisfactory for broadcasting, seed and fertiliser are sometimes lightly r drilled. Drilling ensures a more certain germination and stronger development, but ground

cover is poorer with better opportunity for weeds to develop between the drills. Further preparation of the seed-bed and later broadcasting may be the best procedure, unless the season is well advanced. With bush-burn sowings, .where no preparation of a seed-bed or covering of seed apart from ash is possible, advantage must be taken of favourable conditions for burning . and sowing. Successful burns, suitable grass seed mixtures, and good strikes are important factors in reducing secondgrowth invasion and erosion losses.

Cover Crops

With a few exceptions, permanent pasture should not be sown with a cover crop such as oats or rape, which is apt to smother establishing pasture plants, especially on heavy land. Permanent injury to the sward and reduced production throughout the life of the pasture frequently result from this practice. Early grazing to control the cover crop may injure the young pasture,' especially under wet conditions on ground liable to poach. If stocking is delayed until soil conditions are better, weed smother may result, leaving the pasture weak and open. In Southland and certain other districts spurrey often invades autumnsown pastures and a greenfeed cereal is sometimes grown as a cover crop to repress this weed. However, even ryegrass is repressed by a cereal.

Seed Mixtures In permanent pasture sowings the ultimate association of pasture species which will form the sward should determine the constitution of the seed mixture. Where ryegrass and white clover become dominant they may be the only species sown. With the more lenient grazing management general on dairy farms, grasses such as cocks-

foot, Yorkshire fog, and meadow foxtail usually increase in the swards. This also applies to paspalum in the northerly districts. If allowed to grow unchecked in summer and autumn, paspalum will tend to smother ryegrass and white clover, and a sodbound condition will ultimately result. If kept in check by grazing, assisted if necessary by mowing and stimulated by topdressing, . paspalum-ryegrass-white clover swards are capable of the highest production.

In the preparation of seed mixtures for soils of lower fertility the best of the low-producing species should be. included, as they will become dominant in the sward should fertility fall below that required for the more productive grasses and clovers. This may be anticipated for a bush-burn sowing or on poorer ploughed land where the fertility liberated by cultivation cannot be maintained. Within climatic and economic limitations, the modern practice is to induce soil conditions suitable to the higher-producing pasture plants, and to simplify seed mixtures accordingly.

Good strains of seed with high purity and germination should always he sown. Especially with ryegrass, white clover, and Montgomery red clover, strain is important to the future welfare of the pasture. When seed production is contemplated, the best strains of Certified lines such as Government Stock and Pedigree - seed should be sown, but for general grazing purposes “standard” (or, as they have previously been termed “permanent pasture”) Certified lines are sufficient.

In the limited areas where pastures become ryegrass-white clover swards, the seed mixture may be as follows: lb. per acre. Certified perennial ryegrass ..< 40 , Certified white clover .... 2 421 b. A similar but usually reduced seeding of ryegrass is also used. for seed production in special areas. * A typical seed mixture for highproducing fattening or dairy pastures on well-drained, ploughable land is as follows. lb. per acre. Certified Italian ryegrass . . 5 ” perennial ryegrass . . 20 . ” cocksfoot .... 8 ” white clover ... 2 ” Montgomery red clover 2 ” broad red clover . . 1 • 381 b. In warmer northerly districts where paspalum thrives cocksfoot could be replaced by paspalum. In the south where crested dogstail and also timothy in wetter situations are useful constituents the Italian ryegrass in the above mixture could be replaced by 31b. per acre of dogstail and 21b. per acre of timothy, while cocksfoot could be increased to 121 b. per acre. Fertility is frequently low after second-growth burns, and some adaptation, of the following mixture may be required to suit conditions of fertility: lb. per acre. Browntop . . . . .. . . 3 Danthonia pilosa ... .... 2 Crested dogstail .. .. .. 3 Poa pratensis . . ... . . 1 ■ : Lotus major . . .... . . 1 Certified white clover .... 1 Certified perennial ryegrass . . 8 191 b.

Subterranean clover at 21b. per acre should be included where topdressing will be carried out. SHORT-ROTATION PASTURES, 2 TO 3 YEARS. lb. pet acre. Italian ryegrass . . . . ... 15 Perennial ryegrass . . 15 White clover .... . . ■ 2 Broad red clover .... 4 . ' - -361 b. Hl ryegrass when available in quantity should prove a useful type for short-rotation pasture sowings. TEMPORARY PASTURE. lb. per acre. Italian ryegrass , . . . . . 25 Broad red clover y . , . . . . 6 311 b. ■;

All seed should be bought on purity and germination certificate, while by buying Government Certified seed a good strain is guaranteed.

In the early stages of pasture establishment much will depend on early growth that will permit early stocking. Developing swards are frequently handicapped by not stocking early enough. A short, rapid grazing with a relatively high stock concentration will reduce the smothering effect of the more vigorous early species, encourage tillering, and reduce weed competition. Thirty or more sheep per acre provide the even grazing, urine, droppings, and consolidation essential to vigorous establishment and sward formation. Controlled intermittent grazing with high stock concentration and avoidance of over-grazing or over-

maturity of growth are major factors in development 'of vigorous, even swards. The same control is more difficult and less practicable with extensive hill-country sowings, although basically the same principles apply. Pasture transitions are largely dependent on the grazing management technique. The greater the number of stock that can be carried adequately, the better and more productive grasslands be- _ • come. The more uniform the grazing, the greater the effect of evening up soil fertility through the stock, with reduction in complexity of species making up the sward.