Academic literature on the topic 'Wimmera Southern Mallee'

Under a future climate for south-eastern Australia there is the likelihood that the net effect of elevated CO2, (eCO2) lower growing-season rainfall and high temperature will increase haying-off thus limit production of rain-fed wheat crops. We used a modelling approach to assess the impact of an expected future climate on wheat growth across four cropping regions in Victoria. A wheat model, APSIM-Nwheat, was performance tested against three datasets: (i) a field experiment at Wagga Wagga, NSW; (ii) the Australian Grains Free Air Carbon dioxide Enrichment (AGFACE) experiment at Horsham, Victoria; and (iii) a broad-acre wheat crop survey in western Victoria. For down-scaled climate predictions for 2050, average rainfall during October, which coincides with crop flowering, decreased by 32, 29, 26, and 18% for the semiarid regions of the northern Mallee, the southern Mallee, Wimmera, and higher rainfall zone, (HRZ) in the Western District, respectively. Mean annual minimum and maximum temperature over the four regions increased by 1.9 and 2.2°C, respectively. A pair-wise comparison of the yield/anthesis biomass ratio across climate scenarios, used for assessing haying-off response, revealed that there was a 39, 49 and 47% increase in frequency of haying-off for the northern Mallee, southern Mallee and Wimmera, respectively, when crops were sown near the historically optimal time (1 June). This translated to a reduction in yield from 1.6 to 1.4 t/ha (northern Mallee), 2.5 to 2.2 t/ha (southern Mallee) and 3.7 to 3.6 t/ha (Wimmera) under a future climate. Sowing earlier (1 May) reduced the impact of a future climate on haying-off where decreases in yield/anthesis biomass ratio were 24, 28 and 23% for the respective regions. Heavy textured soils exacerbated the impact of a future climate on haying-off within the Wimmera. Within the HRZ of the Western District crops were not water limited during grain filling, so no evidence of haying-off existed where average crop yields increased by 5% under a future climate (6.4–6.7 t/ha). The simulated effect of eCO2 alone (FACE conditions) increased average yields from 18 to 38% for the semiarid regions but not in the HRZ and there was no evidence of haying-off. For a future climate, sowing earlier limited the impact of hotter, drier conditions by reducing pre-anthesis plant growth, grain set and resource depletion and shifted the grain-filling phase earlier, which reduced the impact of future drier conditions in spring. Overall, earlier sowing in a Mediterranean-type environment appears to be an important management strategy for maintaining wheat production in semiarid cropping regions into the future, although this has to be balanced with other agronomic considerations such as frost risk and weed control.

Crop yield and profitability in the dryland production systems of southern Australia are directly affected by the application of nitrogen (N) and phosphorus (P) fertilisers. How efficiently a crop utilises applied fertiliser is affected by several factors that interact in a complex way, including: nutrient mobility, soil type and soil physicochemical and biological factors, season (including rainfall amount and distribution), and crop physiology. In addition, nutrient supply and crop demand need to synchronise both temporally and spatially if nutrient use efficiency is to be optimised. In this study, the mechanistic simulation model, ROOTMAP, was used to investigate and generate hypotheses about the implications of a range of fertiliser management strategies on the nutrient utilisation of wheat. A range of seasons and 2 commercially important soil types (a Wimmera Vertosol and a Mallee Sodosol) were considered. Simulation results showed a strong interaction between the timing and placement of N and P fertiliser, soil type, seasonal conditions, root growth, and nutrient uptake by wheat. This suggests that region-specific recommendations for fertiliser management may be superior to the ‘one size fits all’ approach typically adopted over the Wimmera/Mallee region. Fertiliser use efficiency differed between the 2 soil types, primarily because physicochemical subsoil constraints were present in the Sodosol, but not the Vertosol. These affected rooting depth, total root system size, and root distribution—notably root growth and hence foraging in the topsoil layer. The root growth response to fertiliser management strategies and seasonal rainfall was also reduced on the Sodosol compared with the Vertosol. Simulated fertiliser uptake was responsive to the placement strategy in a dry year characterised by small rainfall events, typical for the Wimmera and Mallee regions. Shallow placement (0.05 or 0.025 m) of N and P in the topsoil utilised topsoil moisture from these small rainfall events, improving crop N and P uptake. The degree of benefit differed between the 2 soil types, and placement of fertiliser was more effective than topdressing. The simulation approach used here provides a preliminary assessment of a range of fertiliser strategies for different soil type and seasonal conditions. However, because ROOTMAP does not provide direct predictions of grain yield response, simulation results need subsequent validation under field conditions before they can be used by growers.

Buloke Allocasuarina luehmanni woodland is an endangered habitat type that was once widespread in southern Australia but now is restricted to a series of remnants, many of which are located in the Wimmera region of western Victoria. The bird communities inhabiting 27 remnants were sampled on transects of 1.0 ha at 6-week intervals over one year. Ninety-five species of birds were observed in Buloke woodlands, of which 66 species were recorded during transect counts. The total species richness, the richness of groups of birds based on their habitat use, and the composition of assemblages on transects, were examined in a series of analyses with respect to habitat type (which probably reflects "quality"), remnant area, shape, isolation and geographic location. There was little evidence for attributes of remnants significantly influencing species richness per transect, but the composition of avifaunal assemblages varied in relation to habitat type, size and geographic location. The Buloke woodlands supported a diverse assemblage, including numerous species believed to be experiencing a regional decline in southern Australia. The composition of the Buloke assemblage has similarities to those of dry eucalypt woodlands across the plains of central Victoria, but elements contributing to a distinctive avifauna include species associated with semi-arid and mallee environments, and a high frequency of occurrence of a group of small insectivores (thornbills, robins) that favour dry She-oak and Callitris woodlands. A likely reason for the rich representation of small insectivores in woodland stands, even in small degraded remnants grazed by stock, was the scarcity of the Noisy Miner Manorina melanocephala that are often common in eucalypt remnants and known to aggressively exclude other species. The results of this study add weight to the recommendation that protection and restoration of Buloke woodlands is a priority for conservation in the Wimmera bioregion of Victoria.

Soil organic carbon (C) sequestration rates based on the Intergovernmental Panel for Climate Change (IPCC) methodology were combined with local economic data to simulate the economic potential for C sequestration in response to conservation tillage in the six agro-ecological zones within the Southern Region of the Australian grains industry. The net C sequestration rate over 20 years for the Southern Region (which includes discounting for associated greenhouse gases) is estimated to be 3.6 or 6.3 Mg C/ha after converting to either minimum or no-tillage practices, respectively, with no-till practices estimated to return 75% more carbon on average than minimum tillage. The highest net gains in C per ha are realised when converting from conventional to no-tillage practices in the high-activity clay soils of the High Rainfall and Wimmera agro-ecological zones. On the basis of total area available for change, the Slopes agro-ecological zone offers the highest net returns, potentially sequestering an additional 7.1 Mt C under no-tillage scenario over 20 years. The economic analysis was summarised as C supply curves for each of the 6 zones expressing the total additional C accumulated over 20 years for a price per t C sequestered ranging from zero to AU$200. For a price of $50/Mg C, a total of 427 000 Mg C would be sequestered over 20 years across the Southern Region, <5% of the simulated C sequestration potential of 9.1 Mt for the region. The Wimmera and Mid-North offer the largest gains in C under minimum tillage over 20 years of all zones for all C prices. For the no-tillage scenario, for a price of $50/Mg C, 1.74 Mt C would be sequestered over 20 years across the Southern Region, <10% of the simulated C sequestration potential of 18.6 Mt for the region over 20 years. The Slopes agro-ecological zone offers the best return in C over 20 years under no-tillage for all C prices. The Mallee offers the least return for both minimum and no-tillage scenarios. At a price of $200/Mg C, the transition from conventional tillage to minimum or no-tillage practices will only realise 19% and 33%, respectively, of the total biogeochemical sequestration potential of crop and pasture systems of the Southern Region over a 20-year period.

Grain growers are caught in a system of production which is characterised by the privatisation of the farm services sector, global trade, machinery automation, and technologies. The commodity chain is structured so that costs are passed on to farmers through what they buy and sell. As a consequence of this structure, farmers are exploited and subject to the condition of alienation. Previous research has revealed the challenges of farm-scale efficiencies and the demise of rural areas due to farmer-exodus. Since Kautsky’s original publication of The Agrarian Question in 1899, there is still limited material offering a new sociological understanding of farming and the humanistic effects of farm trade. Therefore, this doctoral study is about farmer-exploitation, alienation, and agency, together with the role of political economy, and the function of the commodity chain. It draws upon historical works from labour theorists to seek a better understanding of the humanism of work and participation in commerce in reference to the relations and networks that exist through farming. To trace farmers and their operations, this research uses actor network theory by deploying some of the methods that sit within this approach. Reflexive photography creates a hybrid method with digital images supporting the findings. The photographs in this thesis help to transport the reader to the research setting that is family operated grain growing farms. The key findings are that agency is a property of farmers, land and their machinery. It was found that technology and science facilitated farmer-agency to re-arrange humans and non-humans to hold science stable on farm through strong networks. Technology is responsible for facilitating farmer-agency, which is used as a tool and then it becomes a force, to exert control over farm production. This thesis makes a significant contribution in understanding modern farmer exploitation and how farmers can work to overcome their vulnerability in socio-political economy. This research is place-specific in the dryland agricultural zone of the Wimmera Southern Mallee region of Victoria, but it contributes to a global understanding of what makes farmers act.
Doctor of Philosophy

Fauna living in arid environments face strong ecological and physiological constraints. Water is the key requirement and vertebrates exhibit a range of adaptations for survival. Some species obtain water from their diet, but those which require water to drink or as habitat must either live in or near permanent water, or move in search of water. This strongly influences the distribution and abundance of vertebrate species in arid environments. In arid agricultural landscapes, the development of artificial water sources for stock has benefited water-dependant native fauna, particularly frogs. Little is known about the effects of removal of artificial water sources in these environments. In North-western Victoria, completion of the Northern Mallee Pipeline and the proposed construction of the Wimmera Mallee Pipeline will ultimately replace over 20,000 farm dams, resulting in the widespread loss of an open water resource currently used by fauna across the Wimmera and southern Mallee. The wildlife values of the different on-farm water points in the Northern Mallee Pipeline region and the remaining Wimmera Mallee Domestic and Stock Channel System were examined. Species richness and abundance of vertebrates were surveyed at farm dams, channels and stock troughs in open paddocks, and at farm dams in Mallee woodlands. Mallee woodlands with no available water were also surveyed. Sites were surveyed once per season to determine which species were utilising the different on-farm water points and Mallee woodlands. Knowledge of their usage by different species allowed the importance of each water point type to be determined and the impact of the closure of the channel system to be assessed. The study recorded 57 vertebrate species in the Northern Mallee Pipeline region, including six reptile, 43 bird, seven mammal and zero frog species. Surveys in the Wimmera Mallee Channel/dam region recorded 74 different species, including three reptile , 57 bird, eight mammal and six frog species. Overall species richness and abundance was highest at sites with a farm dam in a Mallee woodland, and the levels of species richness and abundance were significantly higher than at sites with Mallee woodland and no available water. The differences between the two site types were due mainly to greater abundance of water- dependant species at farm dams in Mallee woodland sites. For water points in open paddocks, species richness and abundance was highest at sites with a farm dam in an open paddock and lowest at sites with a stock trough in an open paddock. The difference between the different open paddock water point types were significant, and like woodland sites, were driven by greater numbers of water-dependant species. The study also examined whether purpose-built artificial wildlife ponds could provide habitat for water-dependant fauna and whether artificial wildlife ponds could potentially maintain fauna populations after de-commissioning of the existing channel system. The results of this study showed that artificial wildlife ponds placed in Mallee woodlands can provide habitat for birds, both in the Northern Mallee Pipeline region and the Wimmera Mallee Channel/dam region. The results also showed that these wildlife ponds can support species assemblages at levels comparable to a farm dam in a Mallee woodland, demonstrating that wildlife ponds can be effective in providing a degree of ‘replacement’ habitat for birds on farms. Frogs were not recorded using wildlife ponds situated in Mallee woodlands and this was considered due to the wildlife ponds being placed at least 900 metres from a nearby water source potentially too far for many frog species to disperse in an arid environment. Given these findings, the position of ponds was adjusted for the ponds installed in Black Box woodlands. Wildlife ponds in Black Box woodlands were also successful in providing habitat for birds and functioned as an important source of water for water-dependant birds in summer. Frogs were recorded using the wildlife ponds situated in Black Box woodlands and this was most likely due to their close proximity (<200 metres) to a nearby water source, as well as being located in a wetland-associated vegetation type. The success of the wildlife ponds concept has been demonstrated both in their ability to function as habitat for water-dependant fauna and through widespread community acceptance and support. With the de-commissioning of the channel and dam system removing open water sources from the farming landscape, artificial wildlife ponds installed on farms across the region could provide not just a vital habitat resource supporting water-dependant fauna, but in many areas, the only source of water for wildlife within the Wimmera and southern Mallee regions.
Masters of Applied Science