CLIMATE and pasture production in mid-Canterbury have been discussed by Rickard (1968). Under “dryland” farming conditions, pasture of some 110 to 130 aBys when production is very low reduction is-limited by (1) winters and (2) dry periods of variable incidence and duration during the remainder of the year.
THE HISTORY of agriculture is mainly a record of man’s struggle to adapt his farming to the climate in which he lived, and also of his efforts to become independent of that climate. It is no accident that many of the myths and legends of early man were very much concerned with events closely related to the farming year. Early meetings of a primitive version of Federated Farmers were possibly concerned more with ensuring that the sun returned after mid-winter, with the promise of spring, than with the barter value of the grain crop.
THE OBJECT of this paper is to discuss the ecology of grass grub, Costelytra zealandica White, and porina, Wiseana cervinata (Walker), New Zealand’s most important pastoral insect pests, and to survey what has been achieved in ecological understanding of these insects. The biology and ecology of either or both insects have previously been reviewed by Dumbleton (1942), Miller (1945), Kelsey (1951a, b) and Hoy (1963). The lack of fundamental biological information on grass grub (and this is equally applicable to porina caterpillar) and the need for longterm team studies were stressed, although little sustained, co-ordinated research has since eventuated.
THERE is much information available on New Zealand’s grasslands which indicates the vast difference between various theoretical plant (Mitchell, 1963) and animal (Hutton, 1963) production potentials and what is actually achieved in practice. Although these potentials are often regarded with scepticism, the fact remains that many research and demonstration farms and top farmers now produce quantities of animal products per acre which would have appeared ridiculously high a few years ago. Further, much grassland research is concerned with the identification of factors limiting the attainment of these potentials, as shown by work on treading (Edmond, 1966), nutrient cycling under grazing systems (Sears, 1953), and the optimum stage and intensity of defoliation of pasture plants (Brougham, 1961).
PRODUCTION of rhizobium inoculated and coated lucerne and clover seed was commenced in 1965 by Coated Seed Ltd. in response to a su Scientific and Industria gestion 7 from the Department of Research that it would be a profitable undertaking and would serve the needs of the farming community. Events proved that neither objective could be easily achieved and it became necessary to investigate the seed-inoculum-coat complex in relation to longevity of the rhizobia and to devise manufacturing procedures which would not only meet the objective of effective nodulation in the field but would be economic and provide an acceptable commercial product. In the course of this work on behalf of Coated Seed Ltd., certain principles have been defined which are of interest to research workers and farmers.
MOST of New Zealand’s soils are inherently infertile and fertility has had to be built up per medium of clovers, pasture and grazing animals. On the pastoral land, nitrogen deficiency is the main limiting factor to increased production. The key to improvement lies in the clover plant which has the capacity to supply enough nitrogen for itself and the requirements of the associated grasses. At Palmerston North Sears (1952) found the nitrogen fixed was equivalent to 15 cwt sulphate of ammonia; in Canterbury, 100 lb, equivalent to 5 cwt of sulphate of ammonia, would probably be a reasonable annual average. To utilize the high dry matter produced under favourable conditions, high stock numbers are required which, in association with all-year grazing, favours a rapid buildup of soil fertility. In turn, high soil fertility enables high-yielding crops to be grown and this situation exists in most parts of New Zealand.
THE PURPOSE of this paper is to deal with current grazing methods as practised on high-producing dairy and sheep farms. While an attempt will be made to give a general picture of the situation in New Zealand, Northland experience will be heavily drawn on for several reasons. Northland has given the highest yearly pasture production ever recorded in New Zealand; stock are fed almost entirely on pasture, hay or silage; the high development of clay in Northland soils and the high rainfall mean that pasture damage is a constant threat; and, lastly, it is the district in which the writer works and knows best.
THERE CAN BE few other forage plants which have stimulated a greater volume of research work than lucerne. Although part of the reason for this sustained interest may be its great antiquity as a fodder plant, for lucerne has a documented history of over 2,000 years, of greater importance has undoubtedly been its ability to produce high yields of good quality forage, especially under dry conditions.
MID-CANTERBURY is bounded on the south by the Rangitata River, on the north by the Rakaia River, and stretches from the sea to the Main Divide. The occupied area is 1,300,OOO acres of which 700,000 is improved land comprising the plains and a narrow belt of foothills, while the balance, 600,000 acres, consists of the mountain slopes and inland basins of the high country with a plant cover OF tussock and associated plants. Ignoring the part-time farms, the plain is occupied in approximately 1,500 holdings, giv;ng an average of close to 500 acres, but actual size varies widely with soil type and other factors.
REFERENCE to irrigation in Canterbury generally implies flood irrigation, although there is also a very big investment in sprinkler systems jotted throughout the area and some mention must be made of these.
THE PRINCIPLES involved in making up a pasture seeds mixture are many and complicated, and while considerable attention was paid to these principles in the period between 1910-30 (e.g., Cockayne, 1914, 1917; Levy, 1923, 1936; Stapledon and Davies, 1927, 1928) development of other areas of investigation of sward performance have in recent years tended to overshadow the importance of the species mixture in determining the productivity of a sward.
Commenting on the discovery of subterranean clover in New South Wales in 1896, Mr Maiden, Botanist to the State Government, wrote : “This is not an introduction which need render us uncomfortable.” In making this statement, he could scarcely have foreseen that there would be an estimated 20 to 30 million acres of sown subterranean clover pastures in Australia by the 1950s (Davies, 1952).
THE DATA REQUIREMENTS for an assessment of the profitability of alternative farm management systems are the technical rates of substitution of one enterprise for another, and their price ratios. In a mixed arable system it is necessary to determine relative yields of cash crops, stocking rates and stock performance, and to assess the requirements -of these enterprises for variable and fixed resources. While the basis of analysis would usually .be average yields and current or expected prices, it is often desirable to explore the effect of variation in the critical parameters.
PASTURES vary greatly in production from place to place, from season to season and from year to year. In this review of grasslands research in Canterbury and North Otago, the intention is to emphasize these variations and to identify some of the factors associated with such variations. In particular, it is intended to illustrate the relationships between production of clover-based pastures and lucerne-based pastures and seasonal factors, especially rainfall.
MID-CANTERBURY is the centre of the main small seed growing area of New Zealand and the purpose of this paper, is to show how the growing of these seeds-in particular, the seeds of herbage species-relates to the general farm programme; what problems the seed trade is facing at present; and what might be done to improve the position. The extent to which herbage seeds contribute to the total farm income depends on a number of factors, including soil type, rainfall, nearness to markets and, last but not least, the personal preference of the farmer.
THIS PAPER will describe the role of grassland in the management of an intensive, heavy land, mixed cropping unit farmed in conjunction with a block of light land three miles away. The homestead block of 276 acres was part of the Longbeach estate and was bought by the Crown in 1950. The writer began farming it in March, 1951. The soil is a Temuka heavy silt loam with 5 to 8 in. of topsoil on 15 to 30 in. of clay over shingle and clay. It is extensively tile-drained by the original Longbeach system but still has wet gullies which are difficult to drain and a hindrance to cultivation.
THE PROPERTY to be discussed is a mixed sheep and cropping unit, situated ei ht a miles east of Ashburton and midway between the Ra aia and the Ashburton rivers. Average annual rainfall is 27 in., evenly spread, but there is very high summer evaporation and therefore frequent droughts. On average, the soil is below wilting point for 40 to 50 days each summer. Winters are cold with the soil temperature being below 48°F for about four months each year. The soil is a Lismore stony silt loam averaging 9 in. in depth over gravel.
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