School of Agriculture, Food and Ecosystem Sciences - Theses
Permanent URI for this collection
Search Results
1 - 10 of 10
-
ItemAn evaluation of the role of extension in the Australian pig industry( 1978)Australian agriculture is adjusting to changes in technology, economic circumstances and markets. Extension services as much as the producers' need to change in response to changing industry needs, market trends and consumer demands. There has been much discussion on the problems that these changes present for extension, but none on the basis of empirical research or social science theories. A research program was developed to define the changes taking place in the structure and organisation of the Australian pig industry, and to identify the implications of these changes for pig producers and for extension agencies such as State Departments of Agriculture. The conclusion drawn from the review of the industry situation and from a Delphi survey of 10 experts in the pig industry was that the industry will become more technical and commercialised requiring continual adaptation by the producers to technical and economic changes in order to maintain and increase production efficiency. The survey results showed that a degree of assistance from research and extension was expected by producers to help them maintain and improve production efficiency. Based on the Theory of Personal Constructs, Kelly (1955) an interactive psychological testing procedure known as the Repertory grid was used to record producers' and extension officers' perceptions of each other and of extension services. Twenty pig industry officers, 16 non extension users, 20 extension users and 16 large commercial producers were interviewed. Separate analyses were carried out on the grids of individual subjects, providing profiles of constructs typically used by the subjects in relating to and evaluating people. The results clearly identified the constructs which farmers used in relating to extension advisers and advice. In general, all groups of subjects tended to stereotype people with whom they associated. Combination of both the results within subject groups revealed evidence of commonality within and between the groups in their perceptions. The extension officers saw themselves as progressive and useful while a large number of the producers saw them as theoretical and irrelevant. Extension users held favourable attitudes towards professional agricultural advisers, while large commercial producers and non extension users criticised them on the grounds that they were difficult to communicate with and lacking practical experience. As a group, extension officers were not aware of the questioned relevance of their advice nor of the difficulty experienced by producers in communicating with them. Owing to their practical background and shared experiences, all producers saw other producers as useful and as the most relevant source of advice. The roles they expect him to perform and the characteristics that producers expect from a professional extension adviser have been identified and their implications for the extension officer are discussed. The most obvious implications of the findings are that extension advisers fail to establish the relevance of information within the farmers' context of what is relevant. Based on the findings of the research the theory is proposed that extension programmes will be most successful when producers and extension workers share common perceptions of relevant problems. A philosophy and practice of extension is proposed to meet the farmers' own perception of needs. The interpretation of the results in terms of Personal Construct theory leads to the development of the model of human behaviour, that is, "man as an actor" instead of "man as something being acted upon". A philosophy of extension is developed based on the belief that extension can only be successful if it provides what farmers want. The philosophy states that extension should provide a helping role by facilitating, developing and supporting "man the actor" without dominating or controlling his actions. A practice of extension operating within the boundaries of the proposed new philosophy is developed from the helping relationship model of Carkhuff (1969). The goals of extension are defined as exploration, understanding and action which lead directly to the need for skills which are defined as the "interface skills" of attending, responding, personalising and initiating. The need for and the nature of extension training to provide extension officers with "interface skills" is discussed.
-
ItemGrowth studies in beef cattle( 1962)
-
ItemThe ecology and control of Patersons curse Echium Plantagineum L( 1976)Paterson's curse (Echium plantagineum L.) was introduced into Australia from the Mediterranean regions around the 1850s and is now widespread, especially in the south and east. In many areas, it is a dominant species in pastures and non-agricultural areas. However, the reasons for its widespread success have received little attention in the past. Two other Echium species, viper's bugloss (E. vulgare L.) and Italian bugloss (E. italicum L.), are also naturalized but are much less widespread. In overseas countries, viper's bugloss often is widespread whilst Paterson's curse and Italian bugloss, generally, are only incidental species. Opinions have been divided on the value of Paterson's curse as a forage species. Some farmers and Government bodies regard it as a serious weed and others consider it a useful pasture plant. This conflict is well-reflected in the contrasting common names, Paterson's curse and salvation Jane, given to the plant in the eastern states and South Australia respectively and has arisen, no doubt, because opinions have been based on casual observation rather than critical experimentation. Its condemnation by some as a weed has led to a pre-occupation with control, although most recommendations have advocated the use of herbicides and neglected other management factors. This study investigated some aspects of the physiology and ecology of Paterson's curse in order to provide critical information on the widespread success of the species in southern Australia, and on its fodder value. Farm management practices to control the plant, or minimize problems associated with its presence in pastures, also were investigated. The results of the study suggested that Paterson's curse is widespread and persistent in the Mediterranean-type climatic areas of southern Australia because: (i) seed germination occurs over a wide range of temperatures and is favoured at high temperatures, (ii) seed dormancy is well-developed and allows seed from a single seed crop to germinate sporadically over several years, (iii) seedlings mostly emerge with late summer and early autumn rains, (iv) seedlings are well-adapted to survive during moisture stress, (v) seedlings have a high relative growth rate, (vi) plants are responsive to nitrogen and phosphorus, (vii) plants are not suppressed by competition from sub clover, (viii) plants are not heavily infested and damaged by insects, (ix) plants are persistent and productive when grazed, and highly productive in the absence of grazing, (x) flowering is stimulated by low temperatures and/or long photoperiods, (xi) seed production is high, especially in the absence of grazing, (xii) seeds are readily dispersed by grazing animals and in grain and fodder. Where Paterson's curse is considered a weed, it can be controlled in any year by the use of herbicides, the establishment of competitive species, and the management of grazing stock. However; control measures must be continued and seeding prevented for many years before the plant can be eradicated because well-developed seed dormancy ensures persistence despite failure to seed in any year. In pastures, Paterson's curse is a useful species because it is persistent, highly productive, nutritious, and readily eaten by stock. Moderate grazing during the year is adequate to maintain pasture balance and prevent Paterson's curse from becoming dominant, -rank, and objectionable. Spraying with herbicides to control the plant seems unnecessary because it is expensive', reduces total herbage production, and generally gives only temporary control. On roadsides and waste areas, where grazing pressure is low, the plant may be dominant in some years (e.g. early or false break years) and virtually absent in others (e.g. late break years). Such variation in plant numbers is dependent on climate, independent of man, and typical of many annual, volunteer species. Such non-agricultural infestations are unlikely to spread into surrounding agricultural land that is moderately grazed or cultivated, or undisturbed bushland where soil nitrogen and phosphorus are low, especially if dispersal is not assisted by man. Whether control is necessary in these non-agricultural situations is largely subjective, and depends on the vegetation management policy of the area. However, there seems no reason why Paterson's curse should not be accepted as part of the naturalized vegetation in disturbed, non-agricultural areas.
-
Item
-
Item
-
ItemEfficiency of nitrogen fertilization of dry-seeded rice in south-east Australia( 1986)The efficiency and fate of fertiliser nitrogen applied to combine-sown rice were investigated in field experiments in which fertiliser timing, water regime and soil type were varied. The information gained was used to predict strategies for optimising fertiliser efficiency using current techniques, and to predict and test improved fertilisation technologies. The stage of crop growth, water regime and soil properties all had large and interacting effects on agronomic efficiency. On an infertile alkaline grey clay soil, agronomic efficiency of urea applied at sowing was very low (8 kg kg-1) compared with later applications associated with continuous flooding (up to 56 kg kg-1). The low efficiency was due to nitrification and subsequent de-nitrification during the flushing period. Nitrogen-15 balance studies indicated that 80% of the urea nitrogen was lost from the soil-plant system. The rapid nitrification rate and high loss of nitrogen on the grey soil contrasted with the very low levels of nitrate and low losses of nitrogen (10-25%) from urea applied to rice growing on an infertile acidic red soil under alternating conditions of saturation and aeration (sprinkler-irrigation). Furthermore, on a fertile acidic red soil in the same region, other authors have measured large yield responses to nitrogen applied at sowing. These differences highlight the need to consider soil properties and water management when attempting to predict optimum fertilisation strategies. Yields of sprinkler-irrigated rice (managed to replace water lost by evaporation) were reduced by more than 50% compared with rice grown under continuous flood. However, this was not due to decreased plant uptake or increased loss of fertiliser nitrogen in the sprinkler-irrigated treatments. The low yields appeared to be associated with plant water stress, decreased nitrogen mineralization (by approximately half) and location of the fertiliser nitrogen near the soil surface where root activity was probably restricted due to inadequate moisture. On the grey soil, maximum agronomic efficiencies occurred with application shortly before permanent flood or at early panicle elongation. Efficiency was doubled when urea was applied before permanent flood compared with shortly after permanent flood. The greater efficiency appeared to be associated with the deeper transport of the applied nitrogen into the soil, and consequently lower losses by ammonia volatilisation and/or nitrification/de-nitrification. However, even with the most efficient fertilisation strategies, plant 15N recoveries were less than 40%, while losses exceeded 20%. When the 15N balance data were considered in conjunction with the agronomic data,. it appeared that it would be possible to further increase agronomic efficiency if plant recovery of applied nitrogen could be increased. In particular, minimisation of losses of nitrogen (via nitrification/de-nitrification) from fertiliser applied before permanent flood was a most attractive option. Potential methods identified for increasing agronomic efficiency by minimising losses of nitrogen applied before permanent flood were deep placement and the use of nitrification inhibitors and slow release nitrogen sources. Several experiments were conducted in an attempt to improve fertiliser efficiency by banding urea and modified urea sources 5-7 cm below the soil surface before permanent flood. Plant recovery of 15N was increased by up to 20% with banding compared with surface broadcasting. The best recoveries were from urea super-granules (USG). An experimental fertiliser rig and a commercial seeder fitted with a triple disc assembly were used to band the fertilisers in the main plots. There was no significant yield advantage with banded urea over broadcast urea applied before permanent flood. The fertiliser rig caused considerable plant damage. Using the triple disc applicator, it was possible to band fertiliser below the soil surface with minimal soil disturbance, and plant damage, but only under i ideal conditions of soil moisture. Furthermore, where the soil surface was dry and cracked, penetration with the triple discs was no greater than the depth of the cracks into which surface applied urea prills would be washed upon flooding. The yield test of USG was unsatisfactory because of the excessive plant damage with this method. With current technology, there appears to be little scope for improving the efficiency of urea applied before permanent flood by mechanical placement below the soil surface.
-
ItemThe persistence and productivity of subterranean clover in southern Australia with special reference to rate of development in different cultivars( 1971)Subterranean clover, Trifolium subterraneum L. (commonly referred to as sub clover) has long been recognised as the key to improvement of annual pastures in southern Australia. Although the precise acreage of sub clover is difficult to determine, Donald (1970) has suggested that it may have been sown on as much as 80% of the present estimated area of 50 million acres (20 million ha) 0f sown pasture in this region (see Fig.1). This area (especially the western part of it) has a Mediterranean-type climate with mild wet winters and hot, dry summers. The total annual rainfall varies from about 8 inches (200 mm) to 40 inches (1000 mm) and the length of the growing season (the period during which rainfall relative to evaporation is sufficient to support plant growth) ranges from less than 4 months in the low rainfall areas of Western Australia to 10-11 months in some parts of south-eastern Australia. The species of which the pastures in this area are composed, are predominantly annuals. They become re-established each year following the autumn break, and flower and set seed during the spring prior to over-summering in the seed phase. The autumn break is on average later and the onset of the dry summer period earlier as the annual rainfall becomes smaller, but, in any one location, the year to year variation in the length of the growing period is considerable. In isolated areas reasonable constancy in length of growing period is achieved by autumn and spring irrigation. Pastures may be permanent, becoming re-established each year over an indefinite period, or temporary, in which case a pasture phase of one to several years alternates with a cropping phase, mainly cereals, of 1-3 years. Sub clover has proved to be well adapted to the conditions prevailing in southern Australia and it has played a key role in the pastures because of its capacity to fix atmosphere nitrogen. This together with liberal dressings of superphosphate which have been the rule has greatly improved the fertility status of the soils, thereby increasing the productivity of the pastures themselves and the crops grown in sequence with them. That sub clover had agricultural potential was first realised by Mr A. W. Howard in 1889 in the Mt. Barker district of South Australia, and his efforts to publicise it in the face of public indifference, have been well documented (Hill 1936; Davies 1951; Morley 1961; Symon 1961). There was a period of little progress. Then, through the efforts of many research workers, came an advance in knowledge of the plant and how it could best be used, and, with this, a tremendous increase in its use. There still exists opportunities for its greater use in new areas in southern Australia and for better use in some existing areas. This will require additional research to provide new cultivars and a better understanding of the interaction between genotype and environment. Matching of the genotype with the environment and the importance of this in determining the persistence and productivity of the species will be the main theme of this thesis. The thesis begins with a literature review in which variation within the species and how this is implicated in its widespread use in agriculture are the underlying considerations. This is followed by a report of work concerning the effects of various factors of the environment on the developmental physiology of the plant.
-
ItemInterregional trade in sawntimber in Australia( 1989)The purpose of this study has been to develop a modelling framework which incorporates the essential features of the sawntimber market in Australia and which is capable of being used to study both the interregional trade patterns within Australia and the impacts of various changes on the sector. This firstly involved the determination of demand and supply relationships for the market and secondly the development of a spatial equilibrium model of trade. The basic structure of sawntimber market was studied with the use of two different approaches. The first was an ad hoc, statistical model of the sawntimber market in Australia. The statistical model provided new results for price elasticity of sawntimber demand in Australia. Elasticity of demand for sawntimber was found to be -0.783, an improvement on previous studies which found no relationship between sawntimber demand and the price of sawntimber. It also provided new information on the structure of the sawntimber market in Australia and the substitution between imported and domestic supplies. In particular, the results showed that domestic and imported sawntimber do not compete on the basis of price in the Australian Market. The second approach was through a theoretical model of the production structure of the sawmilling industry using the translog cost function. The estimation of the cost function served two purposes, the first to provide a measure of the slope of the supply curve for the trade model, and the second to provide information about the production structure of the industry. Although .data problems ultimately prevented the use of the translog cost function in the spatial equilibrium model, it did provide new information on input substitution, technological change and scale economies in the sawmilling sector. In particular, the results found that most inputs are substitutes, there are diseconomies of scale, and that technological change has been capital and energy using, and labour saving. The second component of the study was the development of a spatial equilibrium model of the sawntimber sector. This was done with a non-linear programming framework and based on demand and supply elasticities provided by the statistical model. The result was a model which could be used to study the impacts of demand and supply changes. The model was used to study the impact of the forecast increase in log availability by the year 2000. An important result from the use of this model was to demonstrate that an 11.5 percent price decrease could cause the domestic market to absorb 60 percent of the sawntimber which the increased log availability could allow. To summarise, the research encompassed in this thesis has provided new information on the economic structure and performance of the sawntimber sector in Australia. It has also provided a basis for new research and applications of the results. In this study the results were applied to a spatial equilibrium trade model of the sector in Australia. This in turn has provided a new basis for policy analysis in forest industry, in particular issues involving trade and demand or supply shocks.
-
Item
-
Item