School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemA systems analysis approach to drought reserves in the Hamilton region( 1971)Following a discussion of drought strategies available to the grazier, one particular strategy, the holding of drought fodder reserves, is examined in detail. The study estimates the least-cost fodder reserves for a range of stocking rate-pasture production regimes in the Hamilton region. The amount of hay feeding required on any stocking-pasture regime is determined from a simulation model of the grazing complex. In this model, three levels of pasture production are stocked at rates ranging from one to ten wethers per acre. The pasture production assumed ranges from "excellent" (i.e. equivalent to the Hamilton Research Station pastures which produce about 10,000 lb. dry matter per annum) to "poor" (35% less). The climatic inputs into the grazing model are the date of Autumn break, for which a formula is derived, and the June to October rainfall. The pasture sub-model is specified and used to derive the pasture which is "grown" in the grazing model. The sheep aspects of the model are reviewed in detail to derive the relationships which are used in the next set of four sub-models in which animal intake is simulated and liveweight changes determined. This set of four sub-models provides for the four situations of animal intake which may be met. These are: The intake of green pasture alone (i.e. all pasture grown after the Autumn Break); the intake of hay alone; the intake of hay and green pasture together; the intake of hay and dry pasture (pasture remaining when the Autumn Break occurs and dry pasture alone which are handled in the same sub-model) The grazing model was validated for the years 1965-67 using data from the Pastoral Research Station, Hamilton, and showed good agreement for all three years simulated, one of which featured a severe drought. Drought feeding requirements (hay) are determined for each of the years 1879 to 1967 and for the ten stocking rate-pasture production regimes, using specific hay feeding rules. These rules, which aim at sheep survival, do not attempt to specify optimum feeding rates per sheep, and any change in them could significantly alter the drought requirements for any of the regimes studied. Furthermore, the estimates are Lased on the assumption that all sheep are fed through the drought. A pre-drought strategy which permitted the sale of certain classes of sheep at some stage during drought would entail lower feed requirements and might have a lower expected cost, especially at high acquisition costs for feed and low replacement costs for sheep. An inventory analysis is then undertaken, based on a 12 month planning period, which utilises the hay feeding probabilities generated in the grazing model, and provides estimates of the least-cost hay reserve. In contrast to previous studies, the price of hay is related to drought length in calculating the penalty cost of inadequate reserves. The effects of varying several parameters of the inventory model are then examined. The parameters varied are hay costs ($4, $10 and $16 per ton), interest rates (7%, 20% and 50%), and salvage values, and these vary in association with the parameters varied in the grazing model (stocking rate, pasture production and the area closed for hay). At the intermediate values for pasture production and hay cost and a 7 per cent per annum interest rate, the minimum-cost reserve rises sharply, from 2 bales per acre at 2 wethers per acre, to 4.5 bales per acre at 3 wethers per acre, 8 bales per acre at 4 wethers per acre, and 15 bales per acre at 5 wethers per acre. The minimum-cost reserve was found to be relatively insensitive to changes in acquisition costs, except at low stocking rates, where a change in reserve of one or two half-bales per sheep was common as acquisition cost varied over the three levels. The effect of interest rates was also examined for the average pasture regime. On the lowest level of hay acquisition cost, ($4 per ton) increasing the rate of interest from 7 to 50 per cent caused reductions of only one half-bale per sheep. However, at high acqusition cost ($16 per ton) raising the interest rate to 20 per cent resulted in a considerable reduction in the minimum-cost reserve, especially on the lower stocking rates, and raising the interest rate to 50 per cent made holding fodder reserves uneconomic for any stocking rate. One measure of the risk in holding various levels of fodder reserve is the standard deviation of the total expected cost. As expected, it was found that this declines as the reserve is expanded to the maximum ever required. However, only a small reduction in standard deviation results from expanding the reserve beyond the minimum-cost level. Finally, estimates were made of the income-maximising stocking rate for each level of pasture production and hay cost, with the wool price at 30, 40 and 50 cents per lb.. At the intermediate values for pasture production (8,000 lb. D.M.) and hay cost ($10 per ton), and with wool at 30 cents per lb. net, the income-maximising stocking rate was 3 wethers per acre. Each increase of 10 cents per lb. in the wool price was generally associated with an increase of one or two wethers per acre in the income-maximising stocking rate. An increase of 2,000 lb. D.M. (from "average" to "excellent") in average annual pasture production was generally associated with an increase of one wether per acre in the income-maximising stocking rate. A reduction of 1,500 lb. from "average" to "poor" pasture. production reduced the income-maximising stocking rate by about one wether per acre. Increasing the hay cost from $4 to $10 per ton reduced the profit-maximising stocking rate by one wether per acre for all combinations of pasture production and wool price examined. However, a further increase in acquisition cost from $10 to $16 per ton only caused a further reduction in the income-maximising stocking rate at the poor level of pasture production: with average pasture production there was little change and with excellent production there was no change in the income-maximising stocking rate.
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ItemFarm adjustment on the Wimmera plains( 1971)In the past, in some wheat growing areas of Victoria, particularly the Wimmera, there has been almost total reliance on wheat, other enterprises filling a minor role in the farming system. With the introduction of wheat delivery quotas in April 1969, farm operators were faced with a sudden drop in income. The cost-price squeeze has aggravated the income problem. A typical Wimmera Plains wheat farm of 625 acres is small by Australian standards, but it has the potential to produce 7,500 bushels of wheat, or more, under a fertility-maintaining rotation. In 1970-71, however, farms of this size had, on average, a quota of only 4,700 bushels. The possible level of gross income from wheat has been reduced by between $400 and $3,000 per annum, depending on the comparative profitability of alternative enterprises to wheat. The aim of the study was to investigate two important aspects of the farm adjustment problem on the Wimmera Plains; firstly, the best use of resources released from wheat production, and secondly, the potential for adjustment towards optimal resource combinations. A sample of 20 farms, chosen at random from a population of 129, was surveyed in May and June, 1970. The data collected, together with information supplied by the Victorian Department of Agriculture, provided farm planning coefficients. Because of the relatively homogeneous nature of farms with respect to resource complements and enterprise possibilities, the representative farm model approach was considered to be satisfactory for the examination of farm adjustment possibilities on the Wimmera Plains. Using a representative model, linear programming was used to generate profit-maximising farm plans. Variable price programming was used to study the effect of commodity price changes on income. Because of the dominating importance of feed grains in plans, and uncertainty about their prices, enterprise combinations were studied at both "high" and "low" feed-grain prices. To substantiate the results generated for the representative farm model, five of the sample farms were studied individually. When only the "traditional" enterprises (cereals and sheep) were considered, planning results suggested that the five course rotation, pasture, fallow, crop, fallow, crop, with winter-lambing Merino ewes, is the maximum profit plan at both "high" and "low" feed grain prices. Wheat is grown to the level of quota and barley is grown on the remaining cropped area. Income from livestock is minor relative to crop income, providing only 15 to 30 per cent of total gross margin. However, several alternative (or "new') enterprises which are not vet commonly practised in the area were found to offer considerable promise. Oilseed crops, especially oilseed rape, are profitable alternatives to barley, particularly at low feed-grain prices. Even at the current relatively high feed grain prices, and assuming a conservative yield, rapeseed has the potential to lift income from the 625 acre representative farm model by up to $700 per annum. More experience is required with oilseed crops in the area before firm recommendations can be made. Beef cattle, grain feeding of beef, and pigs, can also contribute to increased farm income. Cattle compete directly with sheep for feed, but pigs can be integrated into the existing farming system using farm-grown barley and surplus operator labour. The returns to capital investment in the cattle and pig enterprises were found to be favourable, especially in the case of pigs. If the necessary capital is to be borrowed, however, it is unlikely that there will be surplus disposable income from cattle enterprises during a ten-year repayment period. Gains to the individual farmer from wheat quota negotiability were investigated. The five case-study farms were considered as a "mini-market" for wheat quota under perfect competition. Assuming that the five operators bought or sold quota in order to maximise their income, the average theoretical gain per farm, from negotiability, was between $100 and $200 per annum, depending on the price of barley. In the theoretical quota market seven thousand bushels of wheat quota were exchanged between the five farms. The return to labour and management which is possible on the typical 625 acre Wimmera Plains farm was found to be below an "acceptable" level of $3,500 per annum. However, at current land values, which have fallen substantially since 1968, the purchase or lease of additional land by typical farmers seems to be profitable. Results indicated that the machinery and labour capacity of the "typical" 625 acre property was sufficient to effectively farm more than 1,000 acres. Eleven per cent of the 129 farms in the Wimmera study area were found to be smaller than 500 acres in size. For such farms, additional land as well as additional quota would probably be necessary for viability, at least at low feed-grain prices.
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ItemThe diet and helminth parasites of foxes, dingoes and feral dogs in Victoria( 1973)This thesis was prepared while the author was employed with the Victorian Department of Crown Lands and Survey at the Keith Turnbull Research Station, Frankston. It is in the form of three papers which describe the experimental work and a review of pertinent literature. The literature review outlines the extent of previous knowledge on the subjects of fox diet and fox parasites (helminth) in Australia. A short review of selected overseas studies is included. The experimental work deals with the incidence of various food items and helminth parasites in the gastro-intestinal tracts of foxes, dingoes and feral dogs collected in Victoria during the period from 1968 to 1970. The paper dealing with dingoes and feral dogs has been published (Aust. vet. J., 1972, 48 : 456-461) and the remaining papers have been submitted for publication. All funds for this research project were supplied by the Australian Meat Research Committee.
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ItemEffects of some management factors on sheep and wool production( 1970)It is difficult to be precise about the importance of the contributions made by the many people involved in this work. On a government research station and on private farms, field experiments inevitably involve many people. However, in each chapter presented in this thesis I made a major contribution in the planning, supervising and conducting of the experiment and in preparation of the results for publication. Where authorship has been shared, this is indicated at the beginning of each chapter. Some indication of the relative importance of contributions to this work is as follows:- Chapter I: The experiments were done on two sites, and at one of them Katamitite) I was directly responsible for the work. Chapters II, III: This work undertaken jointly with Mr. J.G. Bath, Chapters IV, V: This work was my responsibility. Chapter VI: The observations on sheep were my responsibility whereas those on pastures were the responsibility of Mr. J. Avery and Mr. I. Cameron. I prepared the manuscripts for chapters I to V and contributed to the preparation of that for chapter VI.
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ItemStudies on the cereal cyst nematode (Heterodera avenae Woll.) in Victoria( 1973)Ten populations of the cereal cyst nematode (Heterodera avenge Will.) from the Victorian Mallee and Wimmera districts, were tested for their variation in pathogenicity, using a selected range of cereal species and cultivars as.indicators. The tests were made in a glasshouse between 1967 and 1969. Of the oats used, Avena sterilis and A.strigosa were resistant, but all other cultivars and species were susceptible to each of the populations. Two barley cultivars, Morocco, and Marocaine 079 were resistant to all populations, but all other barleys used were susceptible. None of the cultivars of wheat was resistant; the spring wheat cv. Loris was very susceptible. Rye cv. South Australian was resistant to all populations. The results indicate that a single biotype of H. avenge is present in Victoria. It appears to be more "aggressive" than any of the biotypes known in Europe. Two hundred and forty cereal species and cultivars (wheat, barley, oats, rye and Triticales) were field . tested for resistance to H. avenge at Sea Lake in the Victorian Mallee between 1966 and 1969. All wheats tested were susceptible to very susceptible, and all Triticales were susceptible. Two barley cultivars Morocco, and Marocaine 079 were resistant and two others moderately resistant. Avena sterilis and A. strigosa were resistant and fifteen cultivars of A. sativa were moderately resistant. Rye cv. South . Australian, posseses a high degree of resistance in contrast to European ryes. The systemic nematicides "Temik" and "Lannate", and the fumigant nematicides ethylene dibromide and dibromochloropropane, were tested for control of H. avenge in a field experiment with Wheat at Sea Lake in the 1968-69 season. All chemical treatments reduced white cyst production, and four of the treatments increased grain yield, and reduced nematode carryover. "Temik" (11 kg/ha broadcast), gave the best nematode control and more than trebled grain yield. "Lannate" (13'kg/ha broadcast) was almost as effective. Dibromochloropropane was an effective nematicide, but was phytotoxic at 56 1/ha. The systemic nematicides "Temik", "Lannate", "Nemafos", "Vydate", "Nemac ur P", and the contact nematicide "Mocap" were tested for control of H. avenge in field experiments with wheat; at Greenland Dam in the Wimmera (1969-70), and at Sea Lake in the Mallee (1969-70 to 1971-72). In one series of experiments all the nematicides were compared on a broadcast basis. All chemical treatments reduced white cyst production and nematode carryover. Plants from plots treated with "Temik" (9 kg/ha) were always cyst-free. "Mocap" when used at the same rate was severely phytotoxic. Grain from plots treated with "Temik" and "Lannate" at the higher rate (9 kg/ha) were analysed for the presence of chemical residues. No "Lannate" residues were detected, and "Temik" residues were less than 0.1 ppm. In a second series of experiments, a comparison was made of methods and rates of application of "Temik" and "Lannate". All broadcast nematicide applications, except those at Sea Lake in 1969-70, reduced white cyst production and nematode carryover. All nematicide applications with superphosphate in the drill row, except for "Lannate" 0.3 kg/ha at Sea Lake in 1971-72, also reduced white cyst production and nematode carryover. Significant grain yield increases were obtained in each experiment. "Temik" (9 kg/ha broadcast, and 2.2 kg/ha in the drill row) consistently gave the best control of H. avenge. Plants from plots receiving these treatments were always cyst-free. In all experiments "Lannate" dusted wheat seed provided little, if any, control of H. avenge. When used at comparable rates of application, "Temik" was a more effective nematicide than "Lannate".
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