School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe effect of the level of nutrition during pregnancy and lactation on the production of grazing sheep, and the interaction between levels of fertility and nutrition( 1956)The livelihood of the sheep farmer depends upon the success with which his ewes produce and rear healthy lambs. This is of particular truth in those areas where fat lambs are produced. It is well known that the production of lambs in large number and in good health depends very largely upon the standard of feeding of the ewes during pregnancy and lactation. however in most areas of the world sheep are restricted to those marginal localities in which the agriculturist finds it difficult to produce milk, eggs or vegetables. Under these conditions, the feeding of pregnant and lactating ewes becomes a task of some difficulty. Where food is in short supply it is very necessary to know at what stage of pregnancy or lactation the plane of nutrition should be raised. Thomson and Thomson (1949) have shown that in Scotland the sheep farmer should feed a supplement to his ewes during late pregnancy. Coop (1950) on the other hand has shown that under his New Zealand conditions, the supplement was best reserved until lactation has commenced. It was thought important to know the effect of different planes of nutrition on pregnant and lactating ewes under the conditions of sheep farming in South Victoria. It was for this reason that the present investigation was undertaken. In addition it was thought to be of interest to determine the interaction "if any" between the level of fertility and that of nutrition
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ItemThesis for degree of Master of Agricultural Science( 1956)The path of a finger of a conventional side-delivery rake is the volume common to an oval cylinder and two warped prisms (one vertical and one horizontal). The shape of the warred prisms depends on operating speeds and rake geometry: the shape of the oval cylinder depends only on rake geometry and is independent of speed. An experimental rake her been developed. The design ensures that, at any operating speed, the crop is moved in a straight line from the swath to the windrow. There is no chance of intermittent contact between the fingers and the crop; each finger moves a small portion of the crop the full distance from the swath to the windrow. The velocity of crop during its passage is constant. At the same time, the velocity of the fingers relative to the ground is significantly less then the velocity of the fingers of a conventional rake.
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ItemEndocrine interactions in the oestrous cycle of domestic animals with particular to the sheep( 1956)A full knowledge of the hormones involved in the oestrous cycle and their interactions, is essential for an understanding of many of the problems associated with fertility of domestic animals. This knowledge is most essential for the study of the control of reproductive phenomena in practical animal husbandry, such for example as the successful breeding of the anoestrous ewe, and the synchronisation of oestrus and ovulation in the cyclic ewe and cow for the purposes of artificial insemination and ovum transplantation. Until recently fundamental studies of the hormones involved in the oestrous cycle have been almost completely confined to laboratory animals. Now, with relatively cheap sources of large quantities of steroid hormones, experimental work is possible using the larger domestic animals. This paper is a report of such studies in the sheep. The fact that most of the literature on this topic is concerned with the small laboratory animals necessitates a brief account of the more pertinent findings for these animals.
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ItemA partial analysis of border check irrigation( 1956)The Border Check method of irrigation, widely used in Australia and overseas for the irrigation of pasture crops, may be described as a method of applying water to land between parallel ridges or checkbanks. Under ideal conditions the land should have no cross slope between the banks, but there is usually a slope in the direction of irrigation. Water is admitted at the head of the strip or irrigation bay, and the flow is diverted when, in the operator's estimation, the ponded water will carry to the end of the strip without wastage. With experience it is possible to judge the cut-off point with considerable accuracy. Depending upon soil type and the natural slope of the ground, bays may be up to 1,200 feet long; and 70 feet wide, with average dimensions of 600 feet by 30 feet. It is the purpose of this thesis to examine some of the factors influencing the movement of water down a border strip, and the infiltration of this water into the soil. It is hoped that such studies will lead ultimately to a more critical assessment of border check layout in relation to soil type, topography, etc., and that it may be possible to determine accurately the dimensions needed for efficient use of irrigation water in a particular case. That efficient irrigation is necessary is brought out by the fact that one inch of excess water passing down to the water table may raise it by as much as one foot (49). The major factors influencing the movement of water down a border strip are as follows :- (1) The infiltration characteristics of the soil. (2) The flow per unit width of border strip. (>) The slope of the land in the direction of flow. (4) The resistance of the plant cover to water movement. Minor factors involved include the soil and water temperatures, the salt content of the irrigation water, the head of water during irrigation, the turbidity of the water, the nature of the soil colloids, etc. Most of these, however, influence irrigation by their effect on the infiltration at a particular point. In the work reported upon herein an attempt has been made to evaluate the influence upon pasture irrigation of the infiltration characteristics of the soil, and the density of pasture cover.
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ItemStudies on the development, activity, and longevity, of the Queensland fruit fly, Strumeta tryoni (Froggatt) and evidence of a cold-hardy Victorian race( 1956)Following the discovery of the Queensland fruit fly, Strumeta tryoni (Froggatt), in Eastern Victoria, a laboratory was set up in 1949 at Bairnsdale for the purpose of studying the fly under controlled conditions, and as a centre from which to carry out field observations. Previous work on S. tryoni in the northern states of Australia had been mainly in the field and concerned with the life history of the fly, with its control by sprays and baits, and with luring methods. In Victoria, the problem was rather different as the possibility of completely eradicating the fly was being considered, and very little was known of its habits or of its life history under Victorian conditions. The original objectives of the investigation were:- To determine the extent of S. tryoni infestation in East Gippsland, Victoria. To study the distribution and fruiting periods of wild plants which are hosts for S. tryoni. To study the life history of S. tryoni under laboratory and under field conditions. Field work included the setting up and replenishing of lure pots hung in wild and in cultivated fruiting plants in districts throughout East Gippsland, the collecting of large numbers of wild fruits, and field cage studies in some districts. Although much time was spent in collecting fruits and maintaining lures throughout the investigation, it became apparent as the work proceeded, that laboratory studies were likely to yield more additional information than were continuous field investigations, as the fly population in East Gippsland was so low that it was difficult to obtain infested wild fruits or to lure many flies. The greater part of this report is, therefore, concerned with a study of the life history of S. tryoni and with laboratory experiments, including the effect of environmental factors during the larval, pupal and adult stages.
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ItemSalting in Victorian catchments: an investigation of soil salinity problems arising under non-irrigated condititons in Victoria( 1956)Salting, that is, the accumulation of excessive amounts of soluble salts in soils, is found in many parts of the world. In Victoria salting is associated with the presence of a permanently saline water table in irrigation districts, or with local accumulations of salt in catchment areas. The results of an investigation, carried out between April 1952, and December 1955, into this second problem, referred to here as catchment salting", are set out in this thesis. The introductory part of the thesis includes evidence regarding the incidence, and economic importance, of catchment salting in the state. The area affected is estimated as nearer 10,000 than 100,000 acres; it is mainly the better class land of valleys, and flats. Salting is extending, but at present its main importance lies in the severe erosion which it induces. In the second part of the thesis, the ecosystems, under which the accumulation of salt in the soils or a catchment can take place, are examined. The factors contributing to such an ecosystem are listed here, with summaries of the conclusions reached: i) Accessions of salt to the soil. In Victoria these salts are largely chlorides of oceanic origin, their presence in soils inland can best be accounted for by the cyclic salt theory. The evidence for this theory is reviewed, and reasons are put forward to account for variations in cyclic salt accessions at different sites. ii) A low precipitation/evaporation ratio. Such a ratio prevails in many parts of Victoria. iii) Vegetative cover with a high water usage. The catchments, in which salting now occurs, were formerly covered with Eucalypt forest, or woodland, making use of rainfall. iv) Soils having an impermeable horizon. at no great depth. Salting in Victoria is confined to catchments with soils of the solodic or solonetzic, type, characterised by a light textured A horizon overlying a heavy clay B horizon. In an undisturbed catchment of this type the hydrological equation can be expressed by: Precipitation = Evaporation + Transpiration. So that, with annual accessions of salt, some accumulation in soils of the catchment is to be expected. In these catchments, which are found chiefly in the 20” – 30” rainfall areas, drastic changes in the hydrological balance have followed settlement. All too frequently catchments have been overcleared, and overgrazed, and the resulting reduction in transpiration has produced a surplus of groundwater, with accelerated water movement downslope. The sub-surface flow over the clay horizon of solodic type soils carries down any soluble salts from the catchment; should this flow be impeded, and saline water brought to the surface, salt is concentrated by evaporation, and salting occurs. A knowledge of the factors responsible for salting will enable an assessment of salting liability in catchments to be made. Three types or salting, seepage, wetpan, and hardpan, found in Victoria, are described, with the types of vegetation which occur on each. The soils of seepage, and wetpan, areas are described as “saline”, and those of hardpan areas as "salinealkali", following the classification used by the U.S. Salinity Laboratories, Riverside, The compacted surface structure of hardpan soils, despite the high soluble salt content, is attributed to the compacting action of raindrops whilst the surface soil is temporarily washed : free of salt, and is in the “alkali” condition. Hardpan formation accounts for the characteristic shallow, and extensively dissected, pattern of erosion on salted land. In the third part of the thesis, the control of salting, and the reclamation of salted land, are dealt with. Correct catchment management, which ensures sufficient vegetative cover, is the surest control measure. Measures such as drainage, the establishment of trees and shrubs, and of improved pastures, are dealt with in a general way. Detailed results are given of trials with fertilizer, and soil improver, treatments; also of trials with some sixty species, and varieties, of grasses, and legumes, on salted land. In the final chapter the evidence, and conclusions, of previous chapters are reviewed, together with recommendations for the treatment of salted land; it therefore provides a more detailed summary, should that be required. Details of soil sampling, analytical methods, plot layout, statistical methods, and some lists, and photographs, of plants, are given in seven appendices.