Autumn-sown Grass; Topdressing Hill Country

New Zealand Journal of Agriculture, Volume 86, Issue 1, 15 January 1953, Page 43

Autumn-sown Grass; Topdressing Hill Country

Seasonal Notes by the Extension Division

SEED-BED PREPARATION FOR AUTUMN-SOWN GRASS

TMPORTANT items of seasonal work are seed-bed prepa- ■ ration for autumn-sown pastures, sowing of cereals for autumn and winter greenfeed, and, if the weather is favourable, autumn pasture topdressing.

The relatively small seeds of grasses and clovers comprising a pasture seeds mixture require a fine, firm, level moist, and

warm seed-bed to ensure even seed distribution at correct sowing depth, and the quick, even establishment of a dense and vigorous sward. Where the ground surface is rough and uneven and the tilth poor and lacking in consolidation, seed becomes unevenly distributed, is covered at varying depths in the soil, and does not contact soil moisture intimately.

On light-textured soils of a sandy or peaty nature underconsolidation frequently causes unsatisfactory pasture establishment, and early preparation and summer fallowing, allowing time to effect natural consolidation, provide the surest means of overcoming this difficulty. Late ploughing and hasty preparations immediately before sowing are doomed to failure, for all too frequently the resultant poor, weedy “strike” and thin, low-productive sward can seldom be improved even by liberal topdressing and the most careful management.

On stiff clay and heavy silt soils over-consolidation, often due to excessive rolling, may prove as serious a limiting factor as under-consolidation on light soil types. Heavy, excessively consolidated soils tend to cake and subsequently dry out and crack, resulting in the death of most seedlings that have managed to penetrate the hard surface. Similarly, the exceedingly fine tilth obtained by too much top working of fine-textured, heavy soils causes the formation after rain of an encrusted surface pan that hampers germination and seedling establishment. Inadequate drainage, even if it does not affect the strike, will almost certainly affect the establishing sward during its first winter.

PRIOR CROP

Autumn-sown grass normally follows (a) a spring-sown forage crop, (b) autumn-

harvested cereals, or (c) summer-fallowed land out of winter crop or old pasture. As February-early March sowing is generally desirable, the spring-sown, autumn-grazed forage crops require early feeding off' to allow adequate preparation of the grass seed-bed.. Rape, early soft turnips, and greenfeed cereal, especially millet, lend themselves to this practice, and field peas, as a green fodder, are a good preparatory crop, provided they can be matured and fed off early enough. On mixed arable farms pastures are often sown after early-harvested autumn-sown cereals, but it is becoming more common to sow after a summer fallow following a fed-off green cereal crop, and this is certainly the best method.

When renewing run-out pastures on all-grass farms, grass to grass establishment proves satisfactory only where cultivations begin early (November-early December) to allow a short summer fallow. The summer fallow is the surest method to obtain a fine, firm, moist, and weed-free seed-bed, especially on heavy, weedy ground or in lowrainfall areas. 1 It has some disadvantages where soils are light and winds persistently strong and where high summer rainfall or pressure of other seasonal work prevents regular weed-control cultivations on the fallow.

CULTIVATION

After cereals the ground is prepared for ploughing either by burning off straw

and stubble or by baling the straw and ploughing in short stubble. Ploughing is followed by top working with discs, and/or hustler, to an increasingly shallow depth, followed by harrowing and rolling.

Heavier soils will require more cultivations than friable loams and lighter types, but the latter may require less discing but several rollings to achieve satisfactory consolidation. On heavy soils, after fodder crops, plough immediately the crop has been fed off and work down with discs and harrows. The use of clod-crusher and roller may or may not be necessary, depending on the friability of the soil and the risk of over-consolidation and caking. On light soils, after rape and turnips, ploughing may be omitted, as discing and harrowing will often achieve the necessary tilth and are less likely to affect consolidation.

Winter-cropped land, especially of a heavy or weedy nature, and most soil types in low-rainfall districts should be prepared by summer fallowing begun by deep ploughing in spring, followed by periodical hustling for weed control and moisture conservation. When proceeding from grass to grass, plough in November-December after close grazing or an early silage cut; roll on the furrow; summer fallow with occasional discings, and complete cultivations with harrows and roller. Where the old pasture forms a matted turf it is advisable to disc or grub the area before deep ploughing or to use skim coulter attachments when ploughing. —A. R. DINGWALL

HILL-COUNTRY TOPDRESSING

THE main plant nutrient deficiency limiting production in the hill country of New Zealand is phosphate, although

there are extensive areas where lime applications would be required to obtain the greatest response from phosphatic fertilisers. Responses shortly after application are usually not required on sheep country and a slower-acting, longer-lasting form of fertiliser may be advantageous. Most phosphatic fertilisers available at present are quite satisfactory for hill-country topdressing: and the inclusion of slower-acting rock phosphates in fertiliser mixtures may have a value in sheep country that: is not so apparent in dairying country.

The rate of application depends primarily on the potential productivity of the land. Heavy dressings of fertilisers cannot be considered economic on land of low productivity unless there, is some factor, such as soil conservation, to consider as well as pasture production. Because application costs are heavy in hill country, it may be better to apply, say, 3cwt. per acre every second year than l|cwt. per acre annually.

The time of application is much less important on hill country than on dairying country, and although autumn topdressings are the most desirable, farmers should not hesitate to apply fertiliser at other seasons if the fertiliser is available and the means of distributing it are to hand.

METHODS OF APPLICATION

The aeroplane has revolutionised hillcountry topdressing. Before 1950 little fertiliser was dropped from the air; in

1950 (year ended 31 March) about 5000 tons; in 1951, 45,000 tons, afe in 1952 about 90,000 tons, were dropped. Aerial application has in 3 years become? the main means of applying fertiliser to hill country and at the same time has been the means of extending thearea topdressed.

Aerial topdressing is not cheap and in certain conditions; the use of blowers can be considered. Blower topdressers,, however, do not give an efficient distribution of fertiliser,, but application costs are low. Finely divided materials. such; as basic slag and North African rock phosphate, which mayhave a place on lime-deficient hill country, are spread! reasonably well by the blower, whereas their fine, dusty nature makes them unsuitable for aerial application. •

—P. B. LYNCH