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1
Sudmeyer, R., and F. Flugge. "The economics of managing tree - crop competition in windbreak and alley systems." Australian Journal of Experimental Agriculture 45, no. 11 (2005): 1403. http://dx.doi.org/10.1071/ea04155.
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Re-introducing trees and shrubs into agricultural landscapes as agroforestry systems establishes a tension between long-term objectives, such as increasing shelter, water use, nature conservation and harvesting tree products, and the short-term objective of maximising crop and pasture profitability. This paper describes the growth of crops, pastures and trees at the tree–crop interface in agroforestry systems and the economic returns from alley farming and windbreak systems using various tree–crop competition management strategies in the Esperance region of Western Australia. Severing lateral tree roots (root-pruning), harvesting mallees and allowing them to coppice, or thinning trees for sawlog regimes increased the yield of crops and pastures in the competition zone. In some instances, these increases were significant: root-pruning increased the annual return from crops grown in the competition zone of Pinus radiata by up to $548/km of the tree line at 1 site. Conversely, root-pruning reduced tree growth by 14–43% across all sites. Therefore, where trees provide benefits, such as shelter from damaging winds, the benefits of reduced tree–crop competition may not offset the consequent reduction in rate of tree growth. For mallee–crop alley systems on agriculturally productive soils, mallee growth rates must be high enough to compensate for crop losses in the competition zone. On less agriculturally productive soils, block-planting mallees may be more profitable than alley systems or crops without competition (sole-crops). This research has shown that competition management strategies can be used to manipulate the relative productivity of trees, crops and pasture at the tree–agriculture interface. The use of these strategies will depend on the relative economic value of tree and crop products and the value placed on other tree benefits, such as shelter and reduced groundwater recharge.
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Jones, H. R., and R. A. Sudmeyer. "Economic assessment of windbreaks on the south-eastern coast of Western Australia." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 751. http://dx.doi.org/10.1071/ea02010.
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Windbreaks in the south-eastern coastal region of Western Australia are generally established to protect agricultural land against damage from wind erosion. However, to date there has been no detailed economic analysis of establishing windbreaks on farms in the region. Accordingly, a decision model was developed to estimate benefits and costs of windbreaks as determined by production inputs and outputs, windbreak system design, frequency and severity of wind damage, and commercial tree products from the windbreak. The model used crop yield responses to shelter at sites across the medium–low rainfall agricultural areas of southern Western Australia. The model lends itself to further development as a risk analysis tool incorporating probabilities and empirical measurements of wind damage. A benefit:cost analysis, using a partial budget approach, compared situations with and without windbreaks. The model showed that windbreaks improved profitability when they reduced the severity of wind damage to crops. Without wind erosion events, windbreaks had a negative impact on farm profit. Investment in windbreaks is therefore a form of insurance. The relative level of benefits is determined by the frequency of wind damage, severity of damage, distance between windbreaks, pruning of lateral tree roots and the possibility of using trees that can produce commercial timber products.
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Sudmeyer, R. A., D. J. M. Hall, J. Eastham, and M. A. Adams. "The tree - crop interface: the effects of root pruning in south-western Australia." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 763. http://dx.doi.org/10.1071/ea02012.
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This paper examines the effect severing lateral tree roots (root pruning) has on crop and tree growth and soil water content at 2 sites in the south-west of Western Australia. Crop and tree growth and soil water content were assessed in a Pinus pinaster windbreak system growing on 0.45–1.00 m of sand over clay, and crop growth was assessed adjacent to Eucalyptus globulus windbreaks growing on 4–5 m of sand. Crop yield was depressed by 23–52% within 2.5 times the tree height (H) of unpruned pines and by 44% within 2.5 H of pruned eucalypts. Depressed yields made cropping uneconomical within 1.5 H of the eucalypts and 1 H of the pines. Root pruning most improved crop yields where lateral tree roots were confined close to the soil surface and decreased in effectiveness as the depth to confining layer (clay) increased. Crop losses within 2.5 H of the pines were reduced from 39 to 14% in the year the trees were root pruned and were 25% 1 year after root pruning. Subsequent root pruning of the eucalypts did not improve crop yield. While root pruning severed lateral pine roots, tree growth was not significantly reduced. The principal cause of reduced crop yield near the trees appeared to be reduced soil moisture in the area occupied by tree roots. Competition for nutrients and light appeared to have little effect on crop yield. Root pruning can spatially separate tree and crop roots where the tree roots are confined close to the surface, and significantly improve crop yields without reducing tree growth.
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Lefroy, E. C., R. J. Stirzaker, and J. S. Pate. "The influence of tagasaste (Chamaecytisus proliferus Link.) trees on the water balance of an alley cropping system on deep sand in south-western Australia." Australian Journal of Agricultural Research 52, no. 2 (2001): 235. http://dx.doi.org/10.1071/ar00035.
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Components of the water balance of an alley cropping system were measured to assess the extent to which tree rows 30 m apart with access to a fresh, perched watertable at 5 m depth were able to capture deep drainage from an inter-cropped cereal–legume rotation. Neutron probe data showed that the 4-year-old trees, cut back to 0.6-m high at the beginning of the experiment, depleted soil water to 2, 4, and 8 m laterally from the tree rows in their first, second, and third years of coppice regrowth, respectively. Combining data from soil water depletion in summer and comparisons of deuterium: hydrogen ratios of groundwater, xylem sap of trees, and herbaceous plants, it was shown that tagasaste trees drew on soil water for 80% of their transpiration in the first winter and 40% in the second, while switching to near total dependence on groundwater each summer and early autumn. Tree water use on a whole plot basis was 170 mm in 1997 (68% from groundwater) v. 167 mm in 1998 (73% from groundwater). Recharge to the perched watertable was estimated to be 193 mm under sole crop in 1998 (52% of rainfall), reducing to 32 mm when uptake of groundwater by trees was included. The degree of complementarity between tagasaste trees and crops in alley cropping used for water management is quantified for 1998 by calculating the ratio of the distance over which trees reduced drainage to zero to the distance over which they reduced crop yield to zero. It is concluded that segregated monocultures of trees and crops would be a more appropriate strategy than a closely integrated system such as alley cropping in this case.
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THONGPHAK, DUANGRAT, and QIAO WANG. "Phylogeny and distribution of the Australian longicorn beetle genus Uracanthus Hope (Coleoptera: Cerambycidae)." Zootaxa 1958, no. 1 (December 8, 2008): 1–16. http://dx.doi.org/10.11646/zootaxa.1958.1.1.
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The Australia genus Uracanthus consists of 39 species and its larvae are known to be borers of at least 31 genera of trees and parasitic plants in 15 families (Asteraceae, Betulaceae, Casuarinaceae, Cupressaceae, Fabaceae, Loranthaceae, Myrtaceae, Pittosporaceae, Proteaceae, Rhamnaceae, Rosaceae, Rutaceae, Sapindaceae, Sterculiaceae, and Xanthorrhoeaceae), including some economically important crops such as citrus, litchi, peach, plum, and apricot. The phylogeny and biogeographic distribution of the genus were investigated in this paper. Here, the monophylies of the genus and seven species groups are inferred based on morphological characters of 39 ingroup and four outgroup species. However, several species groups still need additional steps to become monophyletic and are currently considered paraphyletic. The Uracanthus fauna occur in five biogeographic subregions: the Kosciuskan, Western and Eyrean in southern and central Australia, and the Torresian and Timorian in northern Australia. The fauna are richest with highest endemism in the Kosciuskan and Western. The Kosciuskan and Western are similar in faunal composition and closely related; the Eyrean has probably acted as a faunal exchange transit area between the Kosciuskan and Western, and the two northern Australian subregions have no endemic species. When the areas of endemism of each species are attached to the proposed phylogenetic tree, a clear picture of the distribution patterns of species groups in relation to phylogeny is obtained. It is suggested that the speciation and species radiation of Uracanthus may have occurred first in the Kosciuskan, then in the Western, and finally in the Eyrean, Torresian, and Timorian.
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Oliver, Y. M., E. C. Lefroy, R. Stirzaker, and C. L. Davies. "Deep-drainage control and yield: the trade-off between trees and crops in agroforestry systems in the medium to low rainfall areas of Australia." Australian Journal of Agricultural Research 56, no. 10 (2005): 1011. http://dx.doi.org/10.1071/ar04213.
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In the dryland cropping areas of southern Australia, at risk from dryland salinity, tree belts can improve water management by taking up water unused by crops, with the risk that crop yield will be reduced through competition. As there are few direct markets for tree products grown in the medium to low rainfall areas, the design of agroforestry systems becomes important in reducing the trade-off in crop yield. This study examined some factors that influence the trade-off between crop yield and deep-drainage control in order to develop design guidelines for medium to low rainfall agroforestry. Twenty-one sites in the grain-growing region of Western Australia and southern New South Wales were surveyed over 2 years for crop yields, tree leaf area index, and estimated recharge, providing data from 32 tree–crop interfaces on the relative influence of environmental factors and farming system characteristics on the trade-off between water management and crop yield. The factors most strongly correlated with higher yields were water-gaining sites, orientation that provided shelter from southerly to north-westerly (S, SW, W, NW) winds, and tree age (<10 years). The factors most strongly correlated with the area of cropped land protected against deep drainage were tree age (>10 years), lighter soil types, and low rainfall (<400 mm). Economic analysis of the trade-off required to produce a particular deep-drainage reduction target produced 3 groups of sites: (1) those where trees resulted in a gross margin increase of $15/ha and an estimated deep-drainage reduction of 52% (n = 3), (2) those with a gross margin loss of $49/ha and estimated deep-drainage reduction of 47% (n = 11), and (3) those with a gross margin loss of $163/ha and a deep-drainage reduction of 37% (n = 18). None of the 3 sites in the first group were in the most favourable class in both years, highlighting the vulnerability of a relatively fixed farming system to climate variability.
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Sudmeyer, R. A., M. A. Adams, J. Eastham, P. R. Scott, W. Hawkins, and I. C. Rowland. "Broadacre crop yield in the lee of windbreaks in the medium and low rainfall areas of south-western Australia." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 739. http://dx.doi.org/10.1071/ea02011.
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In Western Australia, the paucity of documented information detailing crop yield in the lee of windbreaks is a constraint to the adoption of tree windbreaks in dryland farming systems. This paper presents grain yield data for crops growing in the lee of windbreaks in the medium to low rainfall areas of the south-west of Western Australia for 64 field years between 1994 and 1997. Two distinct areas were identified in the lee of windbreaks: a zone of reduced crop yield extending 3–5 times the windbreak height (H) from the trees (competition zone), and a zone of unchanged or improved yield extending 15–20 H (sheltered zone). Yield between 1 and 20 H was less than unsheltered yield in years with average rainfall, similar to unsheltered yield in years, or areas, with low rainfall and higher than unsheltered yield if the unsheltered crop was subjected to sandblasting. Changes in microclimate in shelter appeared to be of benefit in increasing crop yields in drier years or areas. Lupin yield was generally increased in the sheltered zone while cereal yield was generally unchanged. The rate of canopy development may be critical to crop response. In dry years, reduced wind speed in shelter reduced evaporation of soil moisture, increasing the amount of soil water available to establishing crops and reducing sandblasting damage. The principle benefit of windbreaks was their ability to reduce wind erosion and subsequent crop damage. As such, windbreaks are best regarded as a form of insurance.
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Sudmeyer, R. A., and P. R. Scott. "Characterisation of a windbreak system on the south coast of Western Australia. 2. Crop growth." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 717. http://dx.doi.org/10.1071/ea02008.
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This paper, which is the second in a series of three, describes dryland crop growth and yields in a windbreak bay in south-western Australia and relates changes to microclimate modification by the windbreaks. Over the 4 years of this trial, above ground biomass and the development rate of crops 3–20 times the tree height from the windbreak (H) were similar to crops growing in unsheltered conditions (more than 20 H from the windbreaks). Grain yield was 16–30% higher between 3 H and 20 H than at more than 20 H in 1994, the driest year on record for the district, in other years yield was largely unchanged. In contrast, above ground biomass growth was consistently less within 3 H than further from the windbreaks and grain yield within 3 H was 19–27% less than unsheltered yield. Water use by the trees is the most likely cause of reduced yield within 3 H. Over the 4 years, mean grain yield between 0.5 H and 20 H was 3.8% greater than yield at more than 20 H. This increase was largely due to the yield increase in 1994. As 5.4% of the paddock was directly occupied by, or uncropped next to, the windbreaks, there was a net yield decrease of 2.8% over 4 years compared to estimated production from a similar area with no windbreaks. The principle benefits of the windbreaks were reducing evaporative demand in extremely dry years and protection against extreme wind events. These benefits must be weighed against the costs of establishing and maintaining windbreak systems.
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Cripps, JEL. "Response of apple trees to soil applications of phosphorus, nitrogen and potassium." Australian Journal of Experimental Agriculture 27, no. 6 (1987): 909. http://dx.doi.org/10.1071/ea9870909.
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An experiment was conducted at Manjimup Research Station in Western Australia from 1973 to 1982 to determine the optimum rates of fertilizer applications for apple trees (Granny Smith/MM.104 and Hi Early Red Delicious/MM.104) growing in a P-deficient soil (about 6 mg/g bicarbonate-extractable P). The trees were planted at 6.1 multiply 6.1 m spacings. Superphosphate at 5 or 8 kg/tree consistently increased fruit set, but the increase varied from year to year from 8 to 91%. Weight of prunings increased by 24-29% and tree height multiply width by 11-16%. When results were averaged over both cultivars, weight of fruits harvested from 1973 to 1982 was increased from 853 to 1226 kg/tree by superphosphate application at 5 kg/tree. Ammonium nitrate applied at up to 4 kg/tree gave small non-significant increases in growth and no increase in weight of fruits harvested for Granny Smith, but the weight of the Red Delicious crop rose by 11%. No response to potassium chloride at 1 kg/tree was found. P fertilizer application increased P concentration in the first fully mature leaves of Granny Smith trees from approximately 0.14% to 0.17-0.19% and in Red Delicious leaves from 0.17 to 0.20-0.21%. N fertilizer application increased N concentration in Granny Smith leaves from approximately 2.3 to 2.5%. Lack of P was the main limiting factor on growth and cropping and it is suggested that the importance of P nutrition in Western Australian apple orchards has been underestimated.
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Bortolussi, G., J. G. McIvor, J. J. Hodgkinson, S. G. Coffey, and C. R. Holmes. "The northern Australian beef industry, a snapshot. 5. Land and pasture development practices." Australian Journal of Experimental Agriculture 45, no. 9 (2005): 1121. http://dx.doi.org/10.1071/ea04013.
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The land and pasture development practices of 375 northern Australian beef properties in 8 regions were surveyed during 1996–97. These properties represented a broad cross-section of the beef industry in terms of geographical location, enterprise and herd size, and ownership structures. Both tree clearing and killing were more common in Queensland than in the Northern Territory or northern Western Australia. In all regions where trees were poisoned, native pasture was more widely used than sowing introduced grass and/or legume species. In contrast, tree clearing was most often accompanied by sowing pastures (either an introduced grass only or introduced grass and legume species together), rather than using native pastures. Central coastal Queensland had the highest use of poisoning trees for pasture development. Tree clearing and using native pasture was most important in central Queensland regions and the Maranoa South West. Sowing introduced pasture species under live trees was more commonly practiced in northern Queensland, the Northern Territory and northern Western Australia than in other regions. A considerable number of introduced grass and legume species were sown by producers. Most of the sown species were grasses. Many of the sown grass and legume species were spreading naturally. Buffel grass was spreading in all areas with < 1000 mm average annual rainfall, but most sown species were spreading only in wetter regions. Stylosanthes spp. were the most commonly spreading legume species in regions with > 500 mm average annual rainfall. The results are discussed in relation to contemporary natural resource management issues and how this may affect land and pasture development activities in the future.
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Byrne, M., and L. Broadhurst. "Genetic diversity and the utilisation of Acacia species complexes in agroforestry in Western Australia." Australian Systematic Botany 16, no. 1 (2003): 49. http://dx.doi.org/10.1071/sb01037.
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Dryland salinity is a major problem in the agricultural areas of Western Australia, having significant detrimental impacts in both agricultural and non-agricultural arenas. Development of new woody perennial tree crops is an option for recharge control in the management of salinity and there is a focus on development of native species that are adapted to low-rainfall areas, with potential for commercial production. Acacia is an important genus for utilisation of woody perennials as there is a large number of species occurring in a wide variety of habitats, and many Acacia species are utilised throughout the world for a range of purposes. In Western Australia, the following three species are of interest for development for commercial utilisation in agroforestry plantings: A.�microbotrya, A. acuminata and A. saligna. All three species show a high degree of morphological variation and are likely to consist of several taxa. Lack of understanding of taxonomic entities and their genetic relationships will hinder the utilisation and development of these species. A combined genetic and taxonomic study has defined the morphological and genetic variation within the A. acuminata complex and identified several taxa. Similar studies will also be expected to define taxa within the A. microbotrya and A. saligna complexes.
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Petersen, Elizabeth, Steven Schilizzi, and David Bennett. "Greenhouse gas and groundwater recharge abatement benefits of tree crops in south-western Australian farming systems." Australian Journal of Agricultural and Resource Economics 47, no. 2 (June 2003): 211–31. http://dx.doi.org/10.1111/1467-8489.00210.
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Anderson, W. K., D. L. Sharma, B. J. Shackley, and M. F. D'Antuono. "Rainfall, sowing time, soil type, and cultivar influence optimum plant population for wheat in Western Australia." Australian Journal of Agricultural Research 55, no. 9 (2004): 921. http://dx.doi.org/10.1071/ar03248.
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In this paper we analyse existing experimental data (grain yield and yield components) from seed rate experiments on wheat in Western Australia, with the aims of determining which factors most influence the optimum plant population, and advancing some practical guidelines for improving the choice of seed rate under rain-fed conditions. Experiments (32) were conducted in the rain-fed cropping zone of Western Australia between 1996 and 2001, using factorial combinations of wheat cultivars (3–25) and target plant populations (4 or 5). Some of them also contained treatments of nitrogen fertiliser (0 or 40 kg/ha of N) or sowing times (2). Each cultivar × plant population dataset (248) was considered to be a record for the sake of the subsequent analyses. Actual plant numbers were counted in each experiment and the optimum plant population was estimated when the slope of an inverse polynomial curve (choosing the most appropriate of the LDL and QDL models in GenStat) fitted to each record was 2.5 kg/ha of grain yield for each extra plant/m2. The optimum populations were initially grouped using a regression tree technique into groups with similar characteristics using pre-sowing rainfall, rainfall in the growing season, sowing date, and soil type. The variables cultivar and nitrogen fertiliser rate were later added to the regression tree analysis. Yield components available for most experiments were used as an aid to interpretation of the results. The optimum plant population varied from 35 to 175 plants/m2 and average grain yields varied from 0.42 to 3.91 t/ha. Rainfall in the growing season (sowing date to harvest date) provided the first split in the regression tree, but pre-sowing rainfall (January to sowing date), sowing date, and soil type further modified the optimum population. The addition of N fertiliser rate as a variable in the regression tree did not induce any different groupings of the optimum population sets, but cultivars were grouped into 4 response types according to pre- and post-sowing rainfall amounts. Where rainfall in the growing season was <205 mm, improved growing conditions due to more pre-sowing rainfall, earlier sowing, and more seasonal rainfall, were associated with higher optimum plant populations. Where rainfall in the growing season exceeded 205 mm, higher pre-sowing rainfall was associated with lower optimum populations. The optimum population was greater on sands than on clay loams. However, on sandy loam soils the optimum was less where rainfall in the growing season was <291 mm, or more for crops sown after 27 May at rainfall >291 mm. Increases in yield components in response to improved growing conditions above about 400 culms/m2, 300 ears/m2, 10 000 kernels/m2, and 600 g/m2 of dry matter at anthesis were not associated with higher optimum plant populations. In general, the optimum plant population increased at about 40 plants/m2 for each tonne of grain yield up to about 3.0 t/ha. The effect of cultivar on the optimum population appeared at yield levels above 2.5 t/ha, but was only detectable when the rainfall in the growing season exceeded 205 mm. Growing conditions and cultivars associated with lower weight per ear (due to fewer kernels and/or lower kernel weight) were associated with higher optimum plant population when the rainfall in the growing season exceeded 205 mm. It is suggested that farmers can make better estimates of the appropriate plant population (and hence can calculate seed rate) on the basis of pre-sowing rainfall (likely stored water), rainfall zone (probability of rainfall in the growing season), sowing date, soil type, and characteristics of individual cultivars where known.
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Sudmeyer, R. A., T. Daniels, H. Jones, and D. Huxtable. "The extent and cost of mallee - crop competition in unharvested carbon sequestration and harvested mallee biomass agroforestry systems." Crop and Pasture Science 63, no. 6 (2012): 555. http://dx.doi.org/10.1071/cp12129.
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Mallee-based agroforestry has potential to provide farmers with new income sources derived from biofuels, biofeedstocks, and carbon sequestration. Although mallees are planted on >12 700 ha across the south-west of Western Australia, very little commercial harvesting of mallee has occurred to date. The development of biomass processing industries is constrained by lack of robust information regarding the productivity of integrated mallee and agricultural systems. This study addresses this constraint by quantifying the productivity and economics of agricultural crops and pastures growing in the competition zone adjacent to mallee belts at 15 sites across the Western Australian wheatbelt. The sites covered a range of climate and edaphic conditions, three mallee species (Eucalyptus polybractea R Baker, E. loxophleba ssp. lissophloia LAS Johnson and KD Hill, or E. kochii ssp. plenissima (CA Gardner) Brooker), various crop and pasture rotations, and various mallee harvest-management treatments. Mallee–crop competition was negatively correlated with rainfall and positively correlated with mallee age and size, and greater for crops than pasture. Consequently, extent and magnitude of competition were highly variable across sites and years. On average, mallee–crop competition extended 11.3 m from unharvested belts and reduced crop and pasture yields by 36% within 2–20 m of the mallee belts relative to open paddock yields. This is similar to what has been reported for taller tree species. Harvesting mallees reduced competition such that crop and pasture yield was reduced by 22 or 27% relative to open paddock yields for mallees harvested at 3- or 6+-year intervals, respectively. The economic cost of mallee–crop competition on agricultural enterprises was also highly variable between sites, and between years within individual sites. Averaged across all site-years, the opportunity cost of competition was equivalent to forgoing agricultural production for 14.4 m on each side of unharvested mallee belts, or 9–10 m on each side of harvested belts. Farmers with mallee agroforestry systems will need to manage the economic impacts of competition by reducing agricultural input costs in the competition zone, timing crop-grazing rotations with mallee harvests, ensuring that the width of alleys is at least 25 times the height of the mature trees, and possibly root-pruning mallees in unharvested or long harvest interval systems. This research has shown that mallee–crop competition presents a significant cost to farmers and must be considered when designing mallee agroforestry systems. The findings have relevance for the development of appropriate biomass and carbon sequestration pricing benchmarks for mallee plantings.
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Sudmeyer, R. A., M. C. Crawford, H. Meinke, P. L. Poulton, and M. J. Robertson. "Effect of artificial wind shelters on the growth and yield of rainfed crops." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 841. http://dx.doi.org/10.1071/ea02018.
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There is great interest in quantifying and understanding how shelter modifies crop growth and development under Australian conditions. Small constructed enclosures (shelters) can consistently reduce wind speed, allowing experiments to be run with replicated sheltered and unsheltered treatments in close proximity. The aim of this study was to quantify the effect on microclimate of consistently reducing wind speed by 70% and explain the consequences for dryland wheat (Triticum aestivum), lupin (Lupinus angustifolius) and mungbean (Vigna radiata) growth and development, at sites in Queensland, Victoria and Western Australia. Crops were grown inside and outside of artificial shelters, 10 by 10 m and extending 1 m above the crop canopy throughout the growing season. Mean daily air and soil temperatures and atmospheric vapour pressure inside the shelters were largely similar to unsheltered conditions. However, clear diurnal trends were evident; daily maximum temperature and vapour pressure deficit (VPD) were increased in shelter when crops were establishing or senescing. When leaf area index (LAI) was reduced in the shelters, soil temperature was greater than in the open, however when LAI was increased in the shelters, soil temperature was less than in the open. Grain yield in shelters ranged between 78 and 120% of unsheltered yield, depending on seasonal conditions and crop species; the mean yield for all sites, crops and years was 99% of unsheltered yield. In the absence of waterlogging, sheltered crops tended to develop more leaf area than unsheltered crops, with an increase in the ratio of leaf area to above-ground biomass. This greater leaf area did not increase soil water use. While LAI was increased by shelter, only 2 of the 6 sheltered crops that were not waterlogged yielded significantly more grain than the unsheltered crops. This may be because the sheltered crops experienced greater maximum temperatures and VPD during anthesis and grain filling than unsheltered crops. Also, net photosynthesis may not have increased in the shelters after canopy closure (LAI>3–4). Lupins, which developed more leaf area inside shelters, may have experienced strong competition for assimilates between developing branches, flowers and fruit. When rainfall was above average and the soil became waterlogged for part of the growing season, grain yield was reduced inside the shelters. Reduced evaporation inside the shelters may have extended the duration and severity of waterlogging and increased stresses on sheltered plants when potential yield was being set. The reductions in wind speed achieved inside the artificial shelters were greater than those likely in conventional tree windbreak systems. Analysis of crop growth illustrated that microclimate modification at this high level of shelter can be both beneficial and harmful, depending on the crop species and climatic conditions during the growing season.
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Hall, D. J. M., R. A. Sudmeyer, C. K. McLernon, and R. J. Short. "Characterisation of a windbreak system on the south coast of Western Australia. 3. Soil water and hydrology." Australian Journal of Experimental Agriculture 42, no. 6 (2002): 729. http://dx.doi.org/10.1071/ea02009.
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This paper describes changes in soil water and ground water at various distances from a Pinus pinaster windbreak in south-western Australia. Soil water contents were measured by neutron moisture meter and time domain reflectometry at distances from a windbreak ranging from 1 to 20 tree heights (H). Within 3 H of the windbreak, soil water storage was reduced by 100–153 mm/1.8 m when compared to unsheltered conditions (20 H) over the 4 years of the experiment. Beyond 3 H, no significant differences in soil water storage were found which could be related to microclimate modification. Relationships between surface soil water storage (mm/0.4 m) at <6�H and 12–24 H were 1 : 1 regardless of the technique used. Similarly, soil water depletion within the crop rootzone (mm/0.6 m) was similar at distances >3 H. Reductions in the depth and duration of perched water levels occurred within 4 H of the windbreak. Despite this, the windbreaks had no effect on the regional ground-water levels.
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Greenwood, E. A. N., E. F. Biddiscombe, A. L. Rogers, J. D. Beresford, and G. D. Watson. "The influence on groundwater levels and salinity of a multi-specied tree plantation in the 500 mm rainfall region of south-western Australia." Agricultural Water Management 25, no. 2 (April 1994): 185–200. http://dx.doi.org/10.1016/0378-3774(94)90045-0.
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Tsou, Christina, Suzanne Robinson, James Boyd, Shruthi Kamath, Justin Yeung, Stephanie Waters, Karen Gifford, Andrew Jamieson, and Delia Hendrie. "Effectiveness and cost-effectiveness of TeleStroke consultations to support the care of patients who had a stroke presenting to regional emergency departments in Western Australia: an economic evaluation case study protocol." BMJ Open 11, no. 1 (January 2021): e043836. http://dx.doi.org/10.1136/bmjopen-2020-043836.
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IntroductionThe Western Australia (WA) Acute TeleStroke Programme commenced incrementally across regional WA during 2016–2017. Since the introduction of the TeleStroke Programme, there has been monitoring of service outputs, including regional patient access to tertiary stroke specialist advice and reperfusion treatment; however, the impact of consultation with a stroke specialist via telehealth (videoconferencing or telephone) on the effectiveness and cost-effectiveness of stroke care and the drivers of cost-effectiveness has not been systematically evaluated.Methods and analysisThe aim of the case study was to examine the impact of consultation with a stroke specialist via telehealth on the effectiveness and cost-effectiveness of stroke and transient ischaemic attack care using a mixed methods approach. A categorical decision tree model will be constructed in collaboration with clinicians and programme managers. A before and after comparison using state-wide administrative datasets will be used to run the base model. If sample size and statistical power permits, the cases and comparators will be matched by stroke type and presence of CT scan at the initial site of presentation, age category and presenting hospital. The drivers of cost-effectiveness will be explored through stakeholder interviews. Data from the qualitative analysis will be cross-referenced with trends emerging from the quantitative dataset and used to guide the factors to be involved in subgroup and sensitivity analysis.Ethics and disseminationEthics approval for this case study has been granted from the Western Australian Country Health Service Human Research and Ethics Committee (RGS3076). Reciprocal approval has been granted from Curtin University Human Research Ethics Office (HRE2019-0740). Findings will be disseminated publicly through conference presentation and peer-review publications. Interim findings will be released as internal reports to inform the service development.
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Turner, Neil C., and Senthold Asseng. "Productivity, sustainability, and rainfall-use efficiency in Australian rainfed Mediterranean agricultural systems." Australian Journal of Agricultural Research 56, no. 11 (2005): 1123. http://dx.doi.org/10.1071/ar05076.
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Mediterranean environments are characterised by hot, dry summers and cool, wet winters. The native vegetation in Mediterranean-climatic regions is predominantly perennial shrubs and trees intermixed with annual forbs. In south-western Australia, the spread of agriculture has seen the well adapted perennial vegetation replaced by rainfed annual crops and pastures. This has increased waterlogging and secondary salinity, thereby causing loss of productivity in ~10% of the cleared land area. To reduce deep drainage and make the agricultural systems environmentally sustainable requires the re-introduction of perennial vegetation in the form of belts of trees or shrubs, and phase-farming systems with perennials such as lucerne replacing annual pastures between the cropping years. To be economically viable, agricultural productivity needs to increase by at least 3% per annum. Yields of dryland wheat, the predominant crop in the Mediterranean agricultural regions of Australia, have increased at ~1%/year for the century preceding the 1980s and since then by nearly 4%/year. Increases have arisen from both genotypic and agronomic improvements. Genotypic increases have arisen from selection for earliness, early vigour, deep roots, osmotic adjustment, increased transpiration efficiency, improved disease resistance, and an improved harvest index from high ear weight (grain number) at flowering and high assimilate storage and remobilisation. Agronomic increases have arisen from early sowing that has been enabled by minimum tillage, increased fertiliser use, especially nitrogen, weed control, and rotations to improve weed control, minimise disease risk, and increase nitrogen availability. Evidence is presented suggesting that the rapid increase in yield of wheat in the last two decades has likely arisen from the rapid adoption of new technologies. For productivity to be maintained in the face of the increasing requirement to be environmentally sustainable will be a challenge and will require better integration of breeding and agronomy.
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Noorduijn, S. L., K. R. J. Smettem, R. Vogwill, and A. Ghadouani. "Relative impacts of key drivers on the response of the water table to a major alley farming experiment." Hydrology and Earth System Sciences 13, no. 11 (November 5, 2009): 2095–104. http://dx.doi.org/10.5194/hess-13-2095-2009.
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Abstract. Widespread clearing of native vegetation in Southwest Western Australia has led to land degradation associated with rising groundwater, secondary salinisation and waterlogging. Re-establishing deep-rooted perennial vegetation across parts of the landscape is one technique for managing land degradation. Alley farming is an agroforestry practice where multiple perennial tree belts are planted in alternation with traditional agricultural crops. To identify the best configuration (belt width versus alley width) for controlling rising groundwater levels and providing viable economic returns, a large scale experiment was established in 1995. The experiment contains seven different alley farming designs, each with transects of piezometers running across tree belts into adjacent alleys to monitor changes in the groundwater level. Two control piezometers were also installed in an adjacent paddock. Groundwater at the site is shallow (<3 m) and of poor quality (pH 3–5, Ec 2.1–45.9 mS cm−1) so root water uptake from the saturated zone is limited. Simple hydrograph analysis could not separate treatment effects on the water table response. Subsequent statistical analysis revealed that 20–30% of the variability in the water table data over the 12 year study period was attributable to the alley farming experiment. To futher investigate the effect of the experiment on groundwater response, additional hydrograph analysis was conducted to compare the trends in the control piezometers in relation to those located within the belts. A difference of 0.9 m was observed between the mean groundwater levels in the control piezometers and the mean levels in the perennial belt piezometers. For a mean specific yield of 0.03 m3 m−3 (standard deviation of 0.03 m3 m−3) this equates to an additional average annual water use of 27 mm yr−1 (standard deviation of 33 mm yr−1) by the perennial agroforestry system. It is concluded that declining annual rainfall is the principal control on hydrograph response at the site, whilst perennial biomass development has a lesser impact on water table depth.
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Groom, Philip K. "Rooting depth and plant water relations explain species distribution patterns within a sandplain landscape." Functional Plant Biology 31, no. 5 (2004): 423. http://dx.doi.org/10.1071/fp03200.
Full textAbstract:
Tree and shrub species of the Banksia woodlands on the sandplains of northern Swan Coastal Plain, Western Australia possess a range of strategies to avoid or tolerate soil water deficits during the annual summer drought. Shallow-rooted shrub species (< 1 m rooting depth) inhabit a range of locations in the landscape, from top of dune crests to wetland embankments. These are the most drought-tolerant of all sandplain species, surviving extremely low summer soil water potentials (< –7 MPa) and tissue water deficits by significantly reducing their transpirational water loss (< 0.2 mmol m–2 s–1). This is in contrast to the few shallow-rooted species restricted to low-lying or seasonally waterlogged areas which are reliant on subsurface soil moisture or groundwater to maintain their relatively high summer water use. Recent studies of water source usage of selected Banksia tree species have shown that these deep-rooted species access groundwater up to a maximum depth of 9 m depth during the summer months, or soil moisture at depth when groundwater was greater than maximum rooting depths, depending on the species. Medium- and deep-rooted (1–2 m and > 2 m, respectively) shrub species cope with the summer soil drying phase and related decrease in groundwater levels by conserving leaf water loss and incurring predawn water potentials between –1 and –4 MPa, enabling them to occur over a range of topographic positions within the sandplain landscape.
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Lovelock, Catherine E., Ilka C. Feller, Maria Fernanda Adame, Ruth Reef, Helen M. Penrose, Lili Wei, and Marilyn C. Ball. "Intense storms and the delivery of materials that relieve nutrient limitations in mangroves of an arid zone estuary." Functional Plant Biology 38, no. 6 (2011): 514. http://dx.doi.org/10.1071/fp11027.
Full textAbstract:
Tropical cyclones can be devastating to ecosystems, but they can also result in pulses of fresh water and sediments delivered in floodwaters to the coastal zone. In the arid zone the pulses provided by cyclones may be particularly important for the maintenance of productivity. We examined the impacts of Cyclone Pancho on growth and nutrient limitations to growth in mangroves on the arid coast of Western Australia. We found that growth of trees was enhanced after the cyclone, more than doubling their rates of stem extension. Fertilisation studies showed that before the cyclone tree growth was nutrient limited. After the cyclone fertilisation treatments had no significant effect on growth, indicating nutrients had been delivered during the storm. Additionally, before the cyclone the efficiency of resorption of phosphorus and nitrogen from senescent leaves was higher than after the cyclone, suggesting that nutrient availability was enhanced. Analysis of stable isotopes of leaf tissue indicated that the cyclone was associated with small changes in water use efficiency, consistent with decreased soil salinity associated with the cyclone. There was, however, significant reductions in δ15N indicating enhanced N supply potentially from a new source. We conclude that in the arid zone, floodwater associated with cyclones is important for the delivery of nutrient subsidies that stimulate mangrove growth and that predicted future reductions in the frequency of cyclones will have negative impacts on the productivity of these ecosystems.
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Temel, F., J. K. Stone, and G. R. Johnson. "First Report of Swiss Needle Cast Caused by Phaeocryptopus gaeumannii on Douglas-Fir in Turkey." Plant Disease 87, no. 12 (December 2003): 1536. http://dx.doi.org/10.1094/pdis.2003.87.12.1536b.
Full textAbstract:
Two 15-year-old Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) test plantations at Artvin, in the eastern Black Sea Coast Region of Turkey, were inspected in July 2003. Trees in both plantations had yellow-to-brown foliage, and most trees retained only the current year's needles, resulting in sparse tree crowns. Numerous minute, black fruit bodies were present along the rows of stomata on the lower surfaces of needles from both plantations. Laboratory examination revealed that the fruiting bodies that emerged through the stomata were those of Phaeocryptopus gaeumannii [Rohde] Petrak, the causal agent of Swiss needle cast (SNC). Although low infection levels are relatively harmless, heavily infected trees lose all but the current year's foliage, with resulting average volume growth reductions of 23 to 52% (2,3). The pathogen occurs throughout the natural range of Douglas-fir in western North America, where it is native, as well as in eastern North America, Europe, Australia, and New Zealand, where both host and fungus have been introduced (1,2). The pathway of introduction of the pathogen to Turkey is unknown. Douglas-fir is the only known host of P. gaeumannii, and the pathogen is not known to be seedborne. Where P. gaeumannii has been introduced outside of western North America, infected nursery stock has been considered the most probable source (1). However, the affected Artvin plantations were established with seedlings produced in Turkey by using seed obtained from various sources. Earlier Douglas-fir plantations in Turkey date from 1953 and were established by using seed originating from France. The possibility that the pathogen could have arrived with untracked Douglas-fir seedlings from outside Turkey imported by arboreta or private nurseries cannot be excluded. Alternatively, scattered Douglas-fir plantations could have served as links between the Artvin infestation and known infested areas in central and eastern Europe, with spread occurring via windborne ascospores, similar to the spread of the pathogen to Denmark from the British Isles (ca. 1930) (1). Presence of severe SNC infections in Douglas-fir test sites at Artvin could hamper efforts to use this species in operational forestry in Turkey. To our knowledge, this is the first report of the occurrence of Swiss needle cast on Douglas-fir in western Asia. Voucher specimens have been deposited in the Oregon State University herbarium (OSC 106394-106403). References: (1) J. S. Boyce. Phytopathology 30:649, 1940. (2) E. M. Hansen et al. Plant Dis. 84:773, 2000. (3) D. Maguire et al. West. J. Appl. For. 17:86, 2002.
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Noorduijn, S. L., K. R. J. Smettem, R. Vogwill, and A. Ghadouani. "The effect of changes in rainfall on the response of the water table to a major alley farming experiment." Hydrology and Earth System Sciences Discussions 6, no. 3 (June 23, 2009): 4563–88. http://dx.doi.org/10.5194/hessd-6-4563-2009.
Full textAbstract:
Abstract. Widespread clearing of native vegetation in Southwest Western Australia has led to land degradation associated with rising groundwater, secondary salinisation and waterlogging. Land degradation can be controlled by re-establishing native deep rooted perennial vegetation across parts of the landscape. Alley farming is an agroforestry practice where multiple perennial tree belts are planted in alternation with traditional agricultural crops. To identify the best configuration (belt width verses alley width) for controlling rising groundwater levels and providing viable economic returns, a large scale experiment was established in 1995. The experiment contains seven different alley farming designs, each with transects of piezometers running across tree belts into adjacent alleys to monitor changes in the groundwater level. Two control piezometers were also installed in an adjacent paddock. At the site groundwater is shallow (<3 m) and of poor quality (pH 3–5, Ec 2.1–45.9 mS cm−1) and so root water uptake from the saturated zone is limited. Simple hydrograph analysis did not identify any treatment effects on the water table response. Subsequent statistical analysis revealed that 20–30% of the variability in the water table data over the 12 year period was attributable to the alley farming experiment. It was hypothesized that a climate trend (reducing annual rainfall over time) may be obscuring the effect of the experiment. To further investigate the effect of the experiment on groundwater response, further hydrograph analysis was conducted to compare the trends in the control piezometers in relation to those located within the belts. A difference of 0.9 m was observed between the mean groundwater levels in the control piezometers and the mean levels in the perennial belt piezometers. For a mean specific yield of 0.03 m3 m−3 this equates to a small additional water use of 27 mm yr−1 by the perennial agroforestry system. It is concluded that declining annual rainfall is the principal control on hydrograph response at the site. Perennial biomass development and perennial root development (both laterally and vertically) exert only a small influence on water table depth. The implications of this study indicate that alley farming has a limited ability to control a rising water table in low lying areas with a shallow saline water table.
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Maina, Solomon, Martin J. Barbetti, Owain R. Edwards, David Minemba, Michael W. Areke, and Roger A. C. Jones. "Zucchini yellow mosaic virus Genomic Sequences from Papua New Guinea: Lack of Genetic Connectivity with Northern Australian or East Timorese Genomes, and New Recombination Findings." Plant Disease 103, no. 6 (June 2019): 1326–36. http://dx.doi.org/10.1094/pdis-09-18-1666-re.
Full textAbstract:
Zucchini yellow mosaic virus (ZYMV) isolates were obtained in Papua New Guinea (PNG) from cucumber (Cucumis sativus) or pumpkin (Cucurbita spp.) plants showing mosaic symptoms growing at Kongop in the Mount Hagen District, Western Highlands Province, or Zage in the Goroka District, Eastern Highlands Province. The samples were blotted onto FTA cards, which were sent to Australia, where they were subjected to high-throughput sequencing. When the coding regions of the nine new ZYMV genomic sequences found were compared with those of 64 other ZYMV sequences from elsewhere, they grouped together, forming new minor phylogroup VII within ZYMV’s major phylogroup A. Genetic connectivity was lacking between ZYMV genomic sequences from PNG and its neighboring countries, Australia and East Timor; the closest match between a PNG and any other genomic sequence was a 92.8% nucleotide identity with a sequence in major phylogroup A’s minor phylogroup VI from Japan. When the RDP5.2 recombination analysis program was used to compare 66 ZYMV sequences, evidence was obtained of 30 firm recombination events involving 41 sequences, and all isolates from PNG were recombinants. There were 21 sequences without recombination events in major phylogroup A, whereas there were only 4 such sequences within major phylogroup B. ZYMV’s P1, Cl, N1a-Pro, P3, CP, and NIb regions contained the highest evidence of recombination breakpoints. Following removal of recombinant sequences, seven minor phylogroups were absent (I, III, IV, V, VI, VII, and VIII), leaving only minor phylogroups II and IX. By contrast, when a phylogenetic tree was constructed using recombinant sequences with their recombinationally derived tracts removed before analysis, five previous minor phylogroups remained unchanged within major phylogroup A (II, III, IV, V, and VII) while four formed two new merged phylogroups (I/VI and VIII/IX). Absence of genetic connectivity between PNG, Australian, and East Timorese ZYMV sequences, and the 92.8% nucleotide identity between a PNG sequence and the closest sequence from elsewhere, suggest that a single introduction may have occurred followed by subsequent evolution to adapt to the PNG environment. The need for enhanced biosecurity measures to protect against potentially damaging virus movements crossing the seas separating neighboring countries in this region of the world is discussed.
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Snowball, R., M. F. D'Antuono, B. J. Cohen, K. Gajda, and R. Bennett. "The value of germplasm nurseries in selecting species for field evaluation." Crop and Pasture Science 61, no. 12 (2010): 957. http://dx.doi.org/10.1071/cp10126.
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This paper documents observations made in irrigated seed multiplication nurseries of novel pasture germplasm to aid in the selection of species for field trials. For the first time it also compares these observations to results from past and concurrent field trials to ascertain the value of observations made in germplasm nurseries in predicting performance in the field. Flowering abundance, seed yield and plant survival over a 2-year period was assessed at four consecutive germplasm nurseries used for seed multiplication between 2002 and 2007. Germplasm included 373 accessions from 67 species and 28 genera of exotic and native perennial forage species, mostly legumes with potential in recharge environments. Classification and regression tree analysis was used to allocate accessions within a species to fewer groups of accessions using the germplasm characteristics. Plant survival and ratings for herbage production in germplasm nurseries were compared to results from field trials for the same species and for the same accessions in order to identify which plant characteristics gave good concordance. Observations from germplasm nurseries were, on the whole, useful in predicting survival of species and accessions in field trials. Ratings for herbage production in germplasm nurseries corresponded poorly with measurements or ratings of herbage production in field trials but, nevertheless, were useful in eliminating some poor-performing germplasm. Several species were identified that had superior survival and seed production in germplasm nurseries, some of which also performed well in field trials, including Dorycnium hirsutum, Kennedia prostrata, Lespedeza juncea var. sericea, Lotononis bainesii and Sanguisorba minor. Western Australian native species had mixed performance in germplasm nurseries but showed promise in field trials, and should be further investigated for their potential in farming systems in southern Australia.
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Biggs, P. H. "Aerial tree volume functions for eucalypts in Western Australia." Canadian Journal of Forest Research 21, no. 12 (December 1, 1991): 1823–28. http://dx.doi.org/10.1139/x91-251.
Full textAbstract:
Large-scale, fixed-base aerial photography is being used together with ground sampling in a major inventory of eucalypt forest in Western Australia. This paper describes the aerial tree volume functions derived for that inventory, covering species in the jarrah (Eucalyptusmarginata) forest. The equations, derived from ground measurements, predict gross bole volume from estimates of total height and vary with the site quality of the forest. They are used to predict volume from photomeasurements of total height that have been corrected for measurement error. The functions appear suitable for this forest type, although the volumes of veteran trees with severely damaged crowns are underestimated.
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MACNISH, G. C. "Mapping rhizoctonia patch in consecutive cereal crops in Western Australia." Plant Pathology 34, no. 2 (June 1985): 165–74. http://dx.doi.org/10.1111/j.1365-3059.1985.tb01346.x.
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Anderson, WK, GB Crosbie, and K. Lemsom. "Production practices for high protein, hard wheat in Western Australia." Australian Journal of Experimental Agriculture 35, no. 5 (1995): 589. http://dx.doi.org/10.1071/ea9950589.
Full textAbstract:
Field experiments were conducted at 18 sites over 4 years in the eastern and north-eastern wheatbelt of Western Australia where average annual rainfall is <400mm, to investigate suitable techniques for the production of high protein (>13%) wheat in an area that traditionally produces grain of a much lower average protein percentage. Wilgoyne yielded as well as, or better than, any of the cultivars accepted into the Special Hard (SH) grade in Western Australia but 5-10% less than cultivars suitable for the Australian Standard White (ASW) grade. Differences between cultivars were greatest at the optimum sowing time in late May. Lower yields in early May were attributed to water stress during early growth or to frost damage during grain filling. The addition of nitrogen (N) fertiliser to crops sown after 1 June was less effective in increasing grain yield and grain protein than N added to earlier sowings. Most crops that produced >13% protein followed medic or field peas. The addition of N fertiliser was seldom required to produce this concentration of protein in crops that followed medic or peas. Crops following pasture with a low legume content or wheat had lower grain protein concentrations. Friable red-brown earth soils in a medic or pea rotation were able to achieve the required grain protein, but other combinations were not extensively tested. From these experiments, cultivars with inherently small grains due to their propensity to produce high levels of small grain screenings (whole grain through a 2-mm, slotted sieve) may be less able to increase yields economically by increasing kernel numbers per unit area under conditions in Western Australia.
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Nevard, Timothy D., Ian Leiper, George Archibald, and Stephen T. Garnett. "Farming and cranes on the Atherton Tablelands, Australia." Pacific Conservation Biology 25, no. 2 (2019): 184. http://dx.doi.org/10.1071/pc18055.
Full textAbstract:
Australia’s two cranes, the brolga (Antigone rubicunda) and Australian sarus crane (Antigone antigone gillae), form dry-season flocks on the Atherton Tablelands in north Queensland, Australia, where they forage almost exclusively amongst planted crops. The long-term relationship between cranes and farmers is therefore critical to their conservation, especially as the cranes can sometimes cause significant economic damage to crops. We interviewed farmers to explore their current attitudes to cranes and their intentions for land use that might affect the birds. We found that most farmers tolerated the cranes, particularly when they feed among stubble. Most, however, are increasing the efficiency of their agronomic practices, harvesting combinable crops such as maize and peanuts in ways that are beginning to reduce post-harvest crop residues. There is also a rapid trend away from field crops to perennial and tree crops that have a higher return per unit area. Both trends may reduce foraging opportunities for the cranes and, unless managed effectively, are likely to increase the potential for damage and conflict with farmers in the field crops that remain.
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WALLACE, J. F., N. A. CAMPBELL, G. A. WHEATON, and D. J. McFARLANE. "Spectral discrimination and mapping of waterlogged cereal crops in Western Australia." International Journal of Remote Sensing 14, no. 14 (September 1993): 2731–43. http://dx.doi.org/10.1080/01431169308904304.
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Coutts, B. A., and R. A. C. Jones. "Incidence and distribution of viruses infecting cucurbit crops in the Northern Territory and Western Australia." Australian Journal of Agricultural Research 56, no. 8 (2005): 847. http://dx.doi.org/10.1071/ar04311.
Full textAbstract:
During 2003–04, a survey was done to determine the incidence and distribution of virus diseases infecting cucurbit crops growing in the field at Kununurra, Broome, and Carnarvon in north-western Australia, Perth in south-western Australia, and Darwin and Katherine in the Northern Territory. Overall, 43 cucurbit-growing farms and 172 crops of susceptible cultivars were sampled. From each crop, shoot samples were collected from plants chosen at random and from symptomatic plants. Shoot samples were sometimes also collected from potential alternative virus hosts (cucurbit volunteer plants and weeds). All samples were tested by enzyme-linked immunosorbent assay (ELISA) using antibodies to Cucumber mosaic virus (CMV), Papaya ringspot virus-cucurbit strain (PRSV), Squash mosaic virus (SqMV), Watermelon mosaic virus (WMV), and Zucchini yellow mosaic virus (ZYMV). Samples from one-third of the crops were also tested by tissue blot immunosorbent assay (TBIA) using generic luteovirus antibodies. Overall, 72% of farms and 56% of crops sampled were virus-infected. The growing areas with the highest incidences of virus infection were Darwin and Carnarvon, and those with the lowest incidences were Katherine and Perth. For WA, overall 78% of farms and 56% of crops were virus-infected, and in the NT the corresponding figures were 55% of farms and 54% of crops. Overall virus incidences in individual crops sometimes reached 100% infection. Crops of cucumber, melon, pumpkin, squash, and zucchini were all infected, with squash and zucchini being the most severely affected. The most prevalent viruses were ZYMV and PRSV, each being detected in 5 and 4 of 6 cucurbit-growing areas, respectively, with infected crop incidences of <1–100%. SqMV was detected in 2 cucurbit-growing areas, sometimes reaching high incidences (<1–60%). WMV and CMV were found in 3 and 4 of 6 cucurbit-growing areas, respectively, but generally at low incidences in infected crops (<1–8%). Infection with luteovirus was found in 3 growing areas but only occurred in 16% of crops. Beet western yellows virus was detected once but at least one other luteovirus was also present. Infection of individual crops by more than 1 virus was common, with up to 4 viruses found within the same crop. Virus-resistant pumpkin cultivars (6 crops) had little infection when adjacent virus-susceptible cucurbit crops had high virus incidences. Viruses were detected in cucurbit volunteer plants and weeds, suggesting that they may act as important reservoirs for spread to nearby cucurbit crops. In general, established cucurbit-growing farms in close proximity to others and with poor crop hygiene suffered most from virus epidemics, whereas isolated farms with large-sized crops or that had only recently started growing cucurbits had less infection. The extent of infection revealed in this survey, and the financial losses to growers resulting from virus-induced yield losses and high fruit rejection rates, are cause for concern for the Australian cucurbit industry.
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Khangura, R. K., and M. J. Barbetti. "Prevalence of blackleg (Leptosphaeria maculans) on canola (Brassica napus) in Western Australia." Australian Journal of Experimental Agriculture 41, no. 1 (2001): 71. http://dx.doi.org/10.1071/ea00068.
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Canola crops were monitored throughout the Western Australian wheatbelt during 1996–99 to determine the incidence and severity of crown cankers caused by the blackleg fungus (Leptosphaeria maculans). All crops surveyed had blackleg. The incidence of crown canker was 48–100%, 15–100%, 9–94% and 48–100% during 1996, 1997, 1998 and 1999, respectively. The mean incidence of crown cankers statewide was 85, 63, 55 and 85% in 1996, 1997, 1998 and 1999, respectively. The severity of crown canker (expressed as percentage disease index) ranged between 30 and 96%, 3 and 94%, 5 and 78% and 21 and 96% during 1996, 1997, 1998 and 1999, respectively. These high levels of blackleg can possibly be attributed to the accumulation of large amounts of infested canola residues. In 1999, there were effects of variety, application of the fungicide Impact, distance to last year’s canola residues and rainfall on the incidence and severity of blackleg. However, there were no effects of sowing date or region on the disease incidence or severity once the other factor effects listed above had been considered. In 1995, an additional survey of 19 sites in the central wheatbelt of Western Australia assessed the survival of the blackleg fungus on residues from crops grown in 1992–94. The residues at all sites carried blackleg. However, the extent of infection at any particular site varied from 12 to 100% of stems with the percentage of stems carrying pseudothecia containing ascospores varying between 7 and 96%. The high levels of blackleg disease found in commercial crops are indicative of significant losses in seed yields, making it imperative that management of blackleg be improved if canola is to remain a viable long-term cropping option in Western Australia.
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Bowman, DMJS. "Monsoon Forests in North-Western Australia. II. Forest-Savanna Transitions." Australian Journal of Botany 40, no. 1 (1992): 89. http://dx.doi.org/10.1071/bt9920089.
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Presence-absence data for tree species in over 1000 quadrats, 10 ° 20m, on 144 transects were analysed by the divisive classificatory program TWINSPAN in order to define wet or dry monsoon forest, ecotone and savanna assemblages. A sorted table revealed that there was continuous floristic variation among these six vegetation types, although the abundance of tree species varied highly significantly between assemblages. Both wet and dry monsoon forests have higher stem densities, greater basal area, more tree species, higher litter cover and lower grass cover than surrounding savannas. Wet monsoon forest soils have significantly more moisture than surrounding savanna, but on the dry monsoon forest-savanna boundary there is no significant difference in soil moisture. Both wet and dry monsoon forest soils are more fertile than those in surrounding savannas, although there is considerable variation in the concentration of nutrients within and between the two forest formations. The greater fertility of the forest probably reflects superior nutrient accretion compared with the savanna, rather than indicating that monsoon forests are restricted to inherently fertile sites. Half the wet monsoon forest boundaries sampled had ecotonal quadrats separating forest from savanna, while only 18% of the dry monsoon forest boundaries had such structurally and floristically intermediate quadrats. A limited number of tree species was found to dominate both wet and dry forest ecotones. Wet forest ecotones are overall environmentally more similar to the surrounding savanna than the adjoining forests. Dry forest ecotones are environmentally intermediate between the dry forest and savanna. Both wet and dry forests have less fire damage than surrounding savannas. In contrast to the edaphic control of most wet monsoon forests, dry forests are typically restricted to fire protected niches. The distribution of both wet and dry forest, ecotone and savanna on boundaries with no edaphic or topographic discontinuities is thought to reflect a dynamic relationship between these assemblages.
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Hamblin, John, Joanne Barton, Milton Sanders, and T. J. V. Higgins. "Factors affecting the potential for gene flow from transgenic crops of Lupinus angustifolius L. in Western Australia." Australian Journal of Agricultural Research 56, no. 6 (2005): 613. http://dx.doi.org/10.1071/ar04313.
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Australian sweet lupins (Lupinus angustifolius L.) and their naturalised wild progenitor occur widely throughout the agricultural zone of Western Australia. Before unrestricted release of transgenic lupins is allowed, an assessment is needed of the likely level of gene flow between the wild and cultivated lupins. Three sets of data were collected to evaluate the likelihood of outcrossing and gene flow. These were the level of outcrossing between adjacent lupin crops, the spatial distribution of crops and wild lupins, and the relative flowering times of the crops and wild lupins. The level of outcrossing within the first 1.5 m of adjacent crops, assessed over 1.56 million plants, was 1 cross in 3600 plants. No crossing was detected at distances greater than 2.25 m (outcrossing rate less than 1 in 148 000). The distribution of 216 crops and 237 wild populations in Western Australia rarely overlapped. Only 5 wild populations were detected in the area where crops were found. No crops occurred in the areas where the remaining wild lupins (232 populations) were found. The crops were all early flowering, whereas the 3 selected wild populations, representing 3 different (medium, high, and very high rainfall) climatic zones, all flowered later. We conclude that the likelihood of gene flow from a transgenic lupin crop to wild lupin populations is extremely low. This is consistent with the fact that reverse gene flow from wild lupins carrying dominant genes for blue flowers and bitter seeds has never been found in farmers’ fields, despite 35 years of lupin cropping where areas of over 1 000 000 ha per year have been grown in Western Australia.
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Mills, N. "BIOLOGICAL PEST CONTROL IN ORGANIC TREE CROPS IN THE WESTERN US: AN OVERVIEW." Acta Horticulturae, no. 1001 (July 2013): 105–10. http://dx.doi.org/10.17660/actahortic.2013.1001.9.
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Seymour, Mark, John A. Kirkegaard, Mark B. Peoples, Peter F. White, and Robert J. French. "Break-crop benefits to wheat in Western Australia – insights from over three decades of research." Crop and Pasture Science 63, no. 1 (2012): 1. http://dx.doi.org/10.1071/cp11320.
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Broadleaf break crops improve cereal yield through disease and weed control, increased nitrogen (N) availability and other mechanisms. In the rainfed farming systems of Australia the magnitude of the yield benefit is highly variable, yet is a major driver for adoption of break crops which are often less profitable and more risky than cereals. Declining area of break crops throughout Australia has re-ignited interest in better understanding the circumstances in which break-crop benefits can be maximised from a farming systems perspective. We compiled and analysed a database of 167 crop sequence experiments conducted throughout Western Australia in the period 1974–2007 to evaluate the impact on wheat (Triticum aestivum L.) grain yield from the use of narrow-leafed lupin (Lupinus angustifolius L.), field pea (Pisum sativum L.), canola (Brassica napus L.) or oats (Avena sativa L.), or following a long fallow where no crop had been sown the previous year. Adjusted for the years in which each was represented the average yield benefit to wheat compared with wheat after wheat was 0.60, 0.45, 0.40, 0.35 and 0.30 t/ha following lupin, field pea, canola, oats or fallow, though direct comparisons between break crops could not be made as few experiments (3) included all species. For all break crops, the mean wheat yield increase was independent of the level of wheat yield, representing a step-change rather than a proportional improvement in yield. Analysis of the larger number and spread of lupin experiments revealed that break-crop benefits increased in higher rainfall areas, following higher yielding lupin crops (>1.5 t/ha), and that the break-crop benefit in terms of yield and water-use efficiency increased significantly after 1991. These observations were often related to the level and/or effectiveness of diseases or grass weed control in the break crop; however, increased contribution of fixed N was also likely with better legume crops. For both lupin and field pea, the magnitude of the break-crop response declined as rate of N fertiliser applied to subsequent wheat crop increased, although non-N related benefits (disease and weed control) tended to dominate wheat response to lupin after 1989. Significant break-crop benefits from lupins (+0.40 t/ha) persisted to a third wheat crop (n = 29) but effects were inconsistent beyond that point. The magnitude, persistence and reliability of the break-crop benefits revealed in this study provide a more accurate framework to assess their likely benefit within the farming system. Further information is required to define the key ‘trigger points’ for the major drivers of the response – water, N, weeds and disease – at which the benefits outweigh the higher risk of these crops and would influence the decision to include them within the system.
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Strydom, Matthys, Ruan Veldtman, Mzabalazo Z. Ngwenya, and Karen J. Esler. "Seed survival of Australian Acacia in the Western Cape of South Africa in the presence of biological control agents and given environmental variation." PeerJ 7 (April 29, 2019): e6816. http://dx.doi.org/10.7717/peerj.6816.
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Studies of invasive Australian Acacia have shown that many seeds are still produced and accumulate in soil stored seed banks regardless of the presence of seed-targeting biological control agents. This is despite claims of biological control success, although there is generally a lack of data on the seed production of invasive Australian Acacia before and after the release of the respective agents. We aimed to quantify seed production and seed survival of invasive Australian Acacia currently under biological control. The seed production and survival (proportion of aborted, predated and surviving seeds) of A. longifolia, A. pycnantha and A. saligna were each studied at four to five sites in the Western Cape of South Africa. The relationships between seed production and stand characteristics were determined and the relative effects of seed predation and abortion on seed survival were established. The investigated invasive Australian Acacia produced many seeds that survived the pre-dispersal stage despite long-term presence of released biological control agents. It was shown that seed crop size is the only significant factor influencing seed survival of the studied Australian Acacia species. Furthermore, the seeds surviving per tree and per square meter were related to tree size. No quantitative evidence was found to suggest that seed-reducing biological control agents are having an impact on the population dynamics of their Australian Acacia hosts. This study illustrates the importance of studying the seed ecology of invasive plants before biological control agents are selected and released.
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Manning, R. "The Beetube — a new honey bee pollination device in Western Australia." Australian Journal of Experimental Agriculture 42, no. 5 (2002): 643. http://dx.doi.org/10.1071/ea01141.
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The development of a simple, durable, lightweight and disposable beehive for high-density (and netted) orchards and crops distant from beekeeping areas provides a useful product and a further diversification for beekeepers involved in professional pollination services. The total weight of a fully developed Beetube ranged from 2.23 to 3.64 kg, contained about 9101 bees, 3038 cm2 of comb, and had a morning and afternoon flight activity of 19-43 and 11-34 honey bees per minute, respectively.
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Owen, Mechelle J., Roslyn K. Owen, and Stephen B. Powles. "A Survey in the Southern Grain Belt of Western Australia Did Not Find Conyza Spp. Resistant to Glyphosate." Weed Technology 23, no. 3 (September 2009): 492–94. http://dx.doi.org/10.1614/wt-08-166.1.
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Glyphosate-resistant crops will be grown for the first time in Western Australia in 2009. A survey was conducted across 150,000 km2 of the southeastern part of the Western Australian grain belt in 2007 to determine whether glyphosate-resistant Conyza populations were present. Sixty-eight Conyza populations were collected from various fields and roadside locations. These populations were collected from areas where Conyza was known to exist. Populations were screened with glyphosate and all populations were found to be glyphosate-susceptible. While no glyphosate-resistant Conyza populations were found in the southeastern grain belt of Western Australia, it provides baseline data prior to the introduction of glyphosate-resistant crops in this region. It is important to monitor the efficacy of glyphosate as resistance becomes more prevalent in weeds of various cropping systems worldwide.
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Abbott, I., and PV Heurck. "Tree Species Preferences of Foraging Birds in Jarrah Forest in Western Australia." Wildlife Research 12, no. 3 (1985): 461. http://dx.doi.org/10.1071/wr9850461.
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A study of foraging by 10 bird species suggests that selective logging of large Eucalyptus marginata will only have affected Melithreptus lunatus, but that proposed silvicultural treatments, including removal of Banksia grandis, may affect several other bird species.
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Hussein, E., D. T. Thomas, L. W. Bell, and D. Blache. "Grazing winter and spring wheat crops improves the profitability of prime lamb production in mixed farming systems of Western Australia." Animal Production Science 57, no. 10 (2017): 2082. http://dx.doi.org/10.1071/an15850.
Full textAbstract:
Grazing immature cereal crops, particularly different varieties of wheat, has become widely adopted in the high rainfall areas of southern Australia. Recently, there has been growing interest in applying this technology in drier parts of the mixed farming zones of Western Australia. A modelling study was conducted to examine farm business returns with or without the grazing of immature wheat (winter and spring varieties) in different locations of Western Australia (Merredin, Wickepin and Kojonup), representing the low to high rainfall (319–528 mm) cropping regions, respectively. A combination of APSIM (crop simulation model) and GrassGro (pasture and livestock simulation model), were used to evaluate the changes in farm gross margins with the grazing of cereal crops at three locations of Western Australia. The results of the study showed that grazing the two wheat varieties (dual-purpose winter and spring) at the high rainfall location increased the profitability of the livestock enterprise by 2.5 times more than grazing crops at both low rainfall locations (P < 0.05). Across all years and sites, the average supplementary feeding costs were reduced by the inclusion of grazed winter (12%) and spring (2%) wheat crops in the lamb production system. The comparative reduction in the cost of supplementary feeding varied between locations and by crop variety within locations, due to both the frequency and average duration of the grazing of wheat crops in these regions, and the farm-stocking rate that was chosen. Both wheat varieties were grazed frequently at the lowest rainfall site (68% and 30% of years for winter and spring wheat varieties respectively), whereas grazing spring wheat was less frequent at the higher rainfall location and averaged 16% of years due to a greater difference in the relative availability of wheat crops versus pasture for grazing among regions. The grazing model assumed that there were abundant productive mixed ryegrass and subterranean clover pasture in the farming system. Overall, this study suggests that both winter and spring wheat crops are likely to supply green feed during the winter feed shortage (April–July) and reduce supplementary feed requirements for a short period of time in some seasons. The value of grazing crops is likely to be higher on farms with poorer soils and less productive pastures.
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Souter, W. D., and J. D. Flanders. "Lake Tinaroo (Australia) – Towards a Management Plan." Water Science and Technology 21, no. 2 (February 1, 1989): 99–104. http://dx.doi.org/10.2166/wst.1989.0034.
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Tinaroo Falls Dam provides a water supply for irrigated agricultural production, primarily tobacco, rice, tree and horticultural crops, near Mareeba in Far Northern Queensland. The increasing popularity of Lake Tinaroo as a recreation and tourist venue is providing impetus for a management plan to be prepared for the lake. Urban and agricultural use of the catchment has caused a change in the trophic state of the lake. The competing uses and emerging issues in relation to a sustainable, healthy lake are discussed. The QWRC is desirous of establishing a management plan for the catchment. Progress in implementing such a plan is discussed.
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Sanford, P., X. Wang, K. D. Greathead, J. H. Gladman, and J. Speijers. "Impact of Tasmanian blue gum belts and kikuyu-based pasture on sheep production and groundwater recharge in south-western Western Australia." Australian Journal of Experimental Agriculture 43, no. 8 (2003): 755. http://dx.doi.org/10.1071/ea02226.
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The effect of Tasmanian blue gum (Eucalyptus globulus) belts and kikuyu (Pennisetum clandestinum) grass on livestock production and groundwater recharge was studied in the high rainfall zone (>600 mm/year) of south-western Western Australia from 1998 to 2001. The objective was to identify optimum combinations of tree belts and pasture for sustainable livestock production and the prevention of secondary salinisation. Treatments were annual pasture, in competition with trees at different orientations (east, west and south), kikuyu pasture in competition with trees at one orientation (west), compared with pasture in the absence of tree competition. Plots had 0, 20 or 36% of their area within 10 m of the tree belt where tree–pasture competition would be expected. Plots (0.48 ha) were stocked with Merino wether hoggets at 12 DSE/ha on annual pastures and 14 DSE/ha on kikuyu pastures. Additional sheep were placed on plots in spring and the annual pasture was destocked in autumn.Within the growing season, herbage mass was similar across both control treatments as a result of varying stock numbers. However, in summer and autumn the kikuyu control contained between 350 and 4900 kg DM/ha more herbage than the corresponding annual pasture. While both pastures accumulated similar amounts of herbage in 1998 and 2000, kikuyu accumulated more in 1999 (11 900 v. 9800 kg DM/ha) as a result of summer rain. Competition from tree belts significantly reduced adjacent annual pasture herbage accumulation (16% average reduction), although there was no difference among the levels of competition. Trees did not significantly affect adjacent kikuyu pasture herbage accumulation. Both carrying capacity and clean wool production per hectare were significantly higher on kikuyu pasture in 1999 and 2000. Tree competition also significantly reduced the carrying capacity of neighbouring annual and kikuyu pasture by an average of 10%. Clean wool production per hectare was significantly lower on annual pasture in combination with trees (11% reduction on average), but there was less effect of competition on kikuyu pasture. The kikuyu pasture used 115, 57 and 132 mm more water than the annual pasture in 1999, 2000 and 2001, respectively. The soil water deficit beneath the trees exceeded that below both control pastures by between 297 and 442 mm.Although the addition of tree belts to annual pasture provided substantial reductions in groundwater recharge, producers would also have to accept losses in livestock production. While kikuyu alone provided significant increases in livestock production and substantial reductions in groundwater recharge, the best compromise was kikuyu in combination with tree belts.
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Bakker, D. M., G. J. Hamilton, D. J. Houlbrooke, C. Spann, and A. Van Burgel. "Productivity of crops grown on raised beds on duplex soils prone to waterlogging in Western Australia." Australian Journal of Experimental Agriculture 47, no. 11 (2007): 1368. http://dx.doi.org/10.1071/ea06273.
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Waterlogging of duplex soils in Western Australia has long been recognised as a major constraint to the production of agricultural crops and pastures. The work described in this paper examines the application of raised beds to arable land that is frequently waterlogged for the production of crops such as wheat, barley, field peas, lupins and canola. Raised beds are 138 cm wide, seed beds separated by 45 cm wide furrows 183 cm apart. These beds were made with a commercial bed former. Seven sites were selected across the south-eastern wheat belt of Western Australia with the experimental areas varying in size from 10 to 57 ha. These large sites were used to accommodate commercial farm machinery. Each site had raised beds formed with a commercial bedformer. The production from the bedded areas was compared with crops grown conventionally on flat ground under minimum tillage as the control. The experiments were established in 1997 and 1998 and the sites were monitored for a maximum of 5 years. In 11 of the 28 site-years of the experiments, grain yields on the raised beds were statistically significantly higher than the yield from crops grown on the control, with an average yield increase of 0.48 t/ha. Across the whole dataset, growing crops on raised beds did not produce significantly lower yields. Below average rainfall was received for much of the experimental period at several sites. Growing season rainfall had a large effect on grain yield and high rainfall over a period of 40 days after seeding significantly increased the grain yield difference between the raised bed and the control. These data indicate that the use of raised beds lead to higher grain yields when seasonal conditions are appropriate.
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Turner, NC. "Crop production on duplex soils: an introduction." Australian Journal of Experimental Agriculture 32, no. 7 (1992): 797. http://dx.doi.org/10.1071/ea9920797.
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Duplex or texture-contrast soils occur over about 60% of the agricultural areas of south-west Western Australia. Annual crops of wheat, barley, oats, and lupins predominate on these soils, grown in rotation with annual pastures. The climate is characterised by cool, wet winters and hot, dry summers. Crop production is restricted to the winter and spring and is limited by waterlogging in the wet winter months and by water shortage during grain filling in spring. Research on crop production on duplex soils has been undertaken for the past 8 years by a collaborative team from the CSIRO Dryland Crops andyoils Program and the Western Australian Department of Agriculture. This research has been focussed on 3 sites at which processes limiting crop production on duplex soils have been highlighted. This special issue was initiated to summarise that research and to put it in its regional and national perspective. Additionally, opportunity was taken to compare and contrast experiences both within Western Australia and throughout Australia, and to draw out management options for crop production on duplex soils.
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Malik, Raj S., Mark Seymour, Robert J. French, John A. Kirkegaard, Roger A. Lawes, and Mark A. Liebig. "Dynamic crop sequencing in Western Australian cropping systems." Crop and Pasture Science 66, no. 6 (2015): 594. http://dx.doi.org/10.1071/cp14097.
Full textAbstract:
During the last two decades in Western Australia, the traditional mixed farming system has been increasingly displaced by intensive crop sequences dominated by wheat. Intensive wheat sequences are usually maintained by using suitable breaks, including pasture, fallow, or alternative cereal, oilseed and legume crops, to control weeds and disease, or maintain the supply of nitrogen to crops. New cereal fungicide options may also assist to maintain intensive cereal systems by suppressing soilborne cereal diseases. To guide the successful diversification of intensive cereal systems, we evaluated the effect of a 2-year experimental matrix of 10 different sequence options. Wheat in the sequence was treated with the fluquinconazole fungicide Jockey (wheat + J) to control soilborne pathogens, or with the usual seed dressing of flutriafol fungicide (wheat – J), used for control of bunts and smuts only. The sequences were wheat + J, wheat – J, barley, grain oats, oaten hay, canola, lupin, field pea, oat–vetch green manure, bare fallow) in which all treatment combinations were grown in year 2 following the same 10 treatments in year 1. In year 3, wheat + J was grown across the entire area as the test crop. In year 2, grain yields of all crops were reduced when crops were grown on their own residues, including wheat (22% reduction), canola (46%), lupin (40%) and field pea (51%). Wheat + J significantly outyielded wheat – J by 300 kg ha–1 in year 1 (14% increase) and 535 kg ha–1 in year 2 (26% increase). Wheat + J was more responsive to break crops than wheat – J in both year 1 and year 2. Break crops sown in year 1, such as canola, fallow, field pea, lupin and oaten hay, continued to have a positive effect on year 3 wheat + J yields. This study has highlighted the importance of break crops to following cereal crops, and provided an example in which a seed-dressing fungicide fluquinconazole in the presence of low levels of disease consistently improved wheat yields.
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Butcher, T. B. "Achievements in forest tree genetic improvement in Australia and New Zealand 7: Maritime pine and Brutian pine tree improvement programs in Western Australia." Australian Forestry 70, no. 3 (January 2007): 141–51. http://dx.doi.org/10.1080/00049158.2007.10675014.
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Maino, James L., Matthew Binns, and Paul Umina. "No longer a west-side story – pesticide resistance discovered in the eastern range of a major Australian crop pest, Halotydeus destructor (Acari: Penthaleidae)." Crop and Pasture Science 69, no. 2 (2018): 216. http://dx.doi.org/10.1071/cp17327.
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The redlegged earth mite, Halotydeus destructor (Tucker) (Acari: Penthaleidae), is an important pest of pastures, broad-acre crops, and vegetables across southern Australia. Populations of H. destructor in Western Australia have been known to be resistant to pyrethroid and organophosphorus pesticides since 2006 and 2014, respectively. Resistant populations are currently widespread across Western Australia’s southern growing region but have, until now, remained undetected in the large south-eastern Australian range of H. destructor, despite ongoing resistance screening since 2006. Following reports of a field control failure in the Upper South East district in South Australia in 2016, resistance testing determined this South Australian population was resistant to pyrethroid and organophosphorus pesticides. The levels of resistance discovered were similar to resistant H. destructor populations in Western Australia, which are associated with chemical control failures. This work confirms for the first-time that pesticide resistant populations of H. destructor are no longer isolated to Western Australia.
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Peralta, Alexandra, and Scott M. Swinton. "Food vs. Wood: Dynamic Choices for Kenyan Smallholders." Sustainable Agriculture Research 5, no. 1 (January 29, 2016): 97. http://dx.doi.org/10.5539/sar.v5n1p97.
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<p>Smallholder farmers in many areas of the semiarid tropics are planting exotic tree species that provide alternative income sources, fuel, and building materials. While providing other benefits, these trees often occupy land that could produce annual food crops. This study uses a polyperiod, linear programming model, to explore the opportunity cost of planting <em>Eucalyptus grandis</em> and <em>Grevillea robusta</em> trees compared to crops in the Nyando watershed of western Kenya. Results of the ten-year period wealth maximization model suggest that a representative farmer’s decisions on farm resource allocation are sensitive to changes in the relative prices of short rotation tree products and annual crops. The model also suggests that there are economic tradeoffs between planting trees and crops, as well as between planting different tree species. Timber production is not likely to replace food crops for two main reasons: (1) the high cost of meeting household subsistence requirements from marketed grains, (2) household cash flow needs met by annual crops. Farmers plant eucalyptus for commercial purposes because they can obtain timber products within four years; however if the prices of these short rotation products go down, farmers will prefer to grow timber from high yield grevillea.</p>