School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe effect of applied N and P under mowing and grazing on the yield and botanical and chemical composition of irrigated pasture and on the nutrient status of a red-brown earth at Kyabram( 1978)A split plot experiment was conducted over 4 years to study the effect of method of harvesting (grazing and mowing) and applied N and P (5 rates of nitrogen ranged from 0 to 112 kg N ha -1 cut-1 and 6 rates of superphosphate ranged from 0 to 188 kg P ha 1 year year-1) on the yield, botanical and chemical composition of irrigated phalaris (Phalaris tuberosa x Phalaris arundinacea)/white clover (Trifolium repens L. cv. Irrigation) pasture and nutrient status of a red-brown earth at Kyabram. A second experiment was conducted over 2 years to find out the effect of rates (0 to 112 kg N ha. 1) and frequency of N application (2, 4 or 8 times year ) o n dry matter production, botanical composition and crude protein content of paspalum (Paspalum dilatatum)/white clover pasture. Results: Mowed plots significantly out-yielded grazed plots in the first two years. However, grazed plots significantly out-yielded mowed plots in the following two years. Nitrogen application significantly (P <0.01) increased dry matter production of grass/clover mixtures. The size of response was governed by the growth rate of pasture species, clover percentage in the sward, climatic conditions and the status of other nutrients in the soil. Splitting N rates in smaller but more frequent applications had no effect on total herbage yield or seasonal distribution. Response to N (kg D.M. kg N-1 ) declined as N rates increased. Phosphorus application up to 94 kg P ha -1 year -1 significantly (P,(0.01) increased pasture production and relative response was greater in winter. Occasionally, the P and N requirements for maximum production were higher for grazing than for mowing. Both methods of defoliation and fertilizer applications affected pasture composition and IT, P and K content in the herbage. Nitrogen application decreased N in the herbage before increasing it and P application up to 141 kg P ha- 1 year -1 increased it. The return by the grazing animal increased total soil N by 106 kg ha 1 year 1 and soil P (Colwell) by 1:0 p.p.m. in four years compared with the start of the experiment. The relationship between plant P and soil P and P rates were significant (P < 0.01). The available soil P decreased with P withdrawal or the application of 23.5 kg P ha-1 year -1 under grazing and 47 kg P ha -1 year-1 under mowing. Phosphorus and nitrogen application significantly affected available soil P. 60-80% of the available P accuminulated in the 0-5 cm and the downward movement increased by increasing P rates. The continuous mowing and P application significantly reduced available soil K. Defoliation method affected C/t:N ratio. Phosphorus application increased soil N whereas N application decreased it. P application at the rate of 23.5 kg ha-1 year-1 increased total soil N by 0.068% which is equivalent to 952 kg N ha-1 in five years. It was estimated that 4 to 4.7 p.p.m of P was required to be removed or added to the soil to change the available soil P by 1 p.p.m. The application of 196 kg N ha-1 year -1 as NH4 NO3 did not change the soil pH and 784 kg N ha 1 year 1 reduced soil pH by an average of ').4 unit.
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ItemFarm size, structural change, and adjustment policy : a study of the dried vine fruit industry in Sunraysia and Robinvale( 1977)Dried vine fruit farms in Sunraysia and Robinvale were nearly all established under closer settlement schemes, with farm size averaging about 8 hectares. The present study indicates that economics of size exist up to a harvested area of about 25 hectares. This would suggest that structural change is occurring in the industry, with farms being amalgamated to take advantage of these economies of size. However, structural change in recent years has been negligible. Some of the obstacles to adjustment are examined in the thesis. They have important implications for government policy; in particular, there is a need for a Land Authority to facilitate adjustment in dried vine fruit growing regions. The thesis also considers some methodological problems in estimating economies of size, and in deriving policy proposals from such estimates. It concludes that the results of most studies of farm size, including this one, must he regarded as provisional, pending the outcome of properly designed empirical tests. It also concludes that the Paretian concept of efficiency is inadequate as a framework for adjustment policy. I would like to thank my supervisors,Mr. G.W. Edwards, Mr. N.H. Sturgess, and Dr. A.S. Watson, for their advice and encouragement during this study. I am also grateful to Mr. John Connell who colaborated on a preliminary statistical analysis (see Section 4.1.6). Acknowledgement is made to the Bureau of Agricultural Economics for the data used in the empirical sections of the thesis. I am grateful to Mrs. Sue Valiance for her excellent typing of the manuscript, and to Mr. Bill Dahl for preparing the diagrams. I was assisted financially by an A.M. White Scholarship and an R.W.S. Nicholas Scholarship. Finally, I would like to thank my wife, Jacky, for her financial support, for help in preparing the bibliography, and for her patient encouragement.
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ItemAn investigation of soil conservation programs and practice( 1978)Group Conservation Areas (GCA's) have been recognised by the Soil Conservation Authority of Victoria as potentially the most efficient strategies for controlling soil erosion and achieving soil conservation on agricultural land. GCA's had several economic and technical advantages over individual farm programs, because conservation programs could be carried out in a planned and co-ordinated manner over contiguous farms. There has been concern in recent years that farmers were not seeing the relevance of and accepting responsibility for maintenance of their mechanical environmental works, nor were they adopting environmental management and improvement practices they had agreed to in their farm conservation plans. The factors which influenced farmers' behaviour as soil conservationists in GCA's were investigated in this research. The focused interview and repertory grid techniques were used to gather information concerning farmers' perceptions about their Soil Conservation programs and practices. This information was interpreted in relation to a theory which explained adult learning and change in soil conservation - Personal Construct Theory. The results show several weaknesses in GCA programs. If such programs are to remain viable several changes are recommended in their strategies. The major areas of weakness are derived from methodological failings; a paternalistic attitude by the Authority is limiting farmers' involvement in direct experience of conservation practices and extension education activities. Recommendations were made for possible changes to help redirect GCA strategies so they became better aligned with the philosophy of adult education.
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ItemThe Victorian scallop fisheries : an economic analysis( 1978)This thesis studies the Victorian scallop industry in an economic framework. It is the first of its kind to be performed on a Victorian fishery. A static model of a scallop fishery is used to investigate whether a reduction in the size of the scallop fleet would be desirable. The implications are examined of various management schemes which would aim to maximise the net economic benefits to be earnt from scallop fishing. Fishing industries and especially those based on highly valued species such as the scallop, have a tendency to be problem industries. The Victorian scallop industry is no exception. The common. property nature of the marine fishery is the root cause of this problem. Left to their own devices fishermen will keep entering a fishery as long as there is incentive to do so. The central hypothesis of this thesis is that the amounts of capital and labour allocated to the Victorian scallop fishing industry are excessive. The common property-theory of a fishery is dealt-with in chapter 2. There a static model of the . fishery is developed through two stages. The first enables the identification of the optimal rate of exploitation given that the objective of management is to maximise resource rent. The second stage of this model enables-the identification of several different optima each according to a form of control or ownership. Consideration is also given to some models which incorporate time as a variable. Chapter 3 deals with fisheries management. It outlines those measures which may be used to control-fishing effort as well as the secondary measures which may also be necessary to control a fishery. Chapter 4 discusses the two Victorian scallop fisheries at Port Phillip Bay and Lakes Entrance. It gives background. information on scallop fishing and a history of past and present management measures. It includes an outline of the management objectives the Fisheries and Wildlife Division of the Ministry for Conservation has in mind when formulating policy. A brief description of the biology of the scallop is given in chapter 5. This is followed by the development of a yield model which. is then applied to the two scallop fisheries. The results of a cost and income survey of scallop fishermen, are reported in chapter 6 and these results are used to calculate linear cost of effort functions for the two fisheries. Chapter 7 draws together the yield and cost of effort functions to produce cost of output functions. These - functions enable the estimation of optimal amounts of effort and catch given that the objective of management was to maximise resource rent. The implications of these results are discussed in chapter 8.