• Authors:
    • Robertson, M. J.
    • Pannell, D. J.
    • Kragt, M. E.
    • Thamo, T.
  • Source: Agricultural Systems
  • Volume: 112
  • Year: 2012
  • Summary: Carbon sequestration in agricultural soil has been identified as a potential strategy to offset greenhouse gas emissions. Within the public debate, it has been claimed that provision of positive incentives for farmers to change their land management will result in substantial carbon sequestration in agricultural soils at a low carbon price. However, there is little information about the costs or benefits of carbon sequestration in agricultural soils to test these claims. In this study, the costeffectiveness of alternative land-use and land-management practices that can increase soil carbon sequestration is analysed by integrating biophysical modelling of carbon sequestration with wholefarm economic modelling. Results suggest that, for a case study model of a crop-livestock farm in the Western Australian wheatbelt, sequestering higher levels of soil carbon by changing rotations (to include longer pasture phases) incur considerable opportunity costs. Under current commodity prices, farmers would forego more than $80 in profit for every additional tonne of CO2-e stored in soil, depending on their adoption of crop residue retention practices. This is much higher than the initial carbon price of $23 t(-1) in Australia's recently legislated carbon tax. This analysis does not incorporate the possibility that greenhouse gas emissions may increase as a result of including longer pasture phases. Accounting for emissions may substantially reduce the potential for net carbon sequestration at low carbon prices.
  • Authors:
    • Cockfield, G.
    • Maraseni, T. N.
  • Source: Agricultural Water Management
  • Volume: 103
  • Year: 2012
  • Summary: Irrigated cropping helps stabilise farm and regional income and contributes to productivity gains but the net benefits should include the full cost of water and greenhouse gas (GHG) emissions. This study examines the costs and returns of switching from a dryland rotation for four crops in the Darling Downs region of Australia, to a rotation of the same crops under irrigation, including greenhouse gas (GHG) values. The value chain, including all inputs was identified and emissions estimated using a range of studies and models. Over four year cropping cycle, the irrigated system would result in more than six times the emissions than from the dryland system. If GHG and water prices are not embedded in the production process, irrigation is more profitable per hectare. In this scenario, the landholder makes more than twice as much from the irrigated crops, with gross margins for the dryland and irrigated crop rotations of $1597 and $3490/ha, respectively. If the value of GHGs is included, the gap closes but irrigated crops are still more profitable. If however, a relatively high cost of the water, based on price ranges from the last decade, is included, then dryland crops are financially preferable. These results could be useful in designing national mitigation and water buy-back policies, both of which are being developed in Australia.
  • Authors:
    • Reardon-Smith, K.
    • Mushtaq, S.
    • Maraseni, T. N.
  • Source: Journal of Environmental Management
  • Volume: 111
  • Year: 2012
  • Summary: The Australian Government is meeting the challenge of water scarcity and climate change through significant on-farm infrastructure investment to increase water use efficiency and productivity, and secure longer term water supplies. However, it is likely that on-farm infrastructure investment will alter energy consumption and therefore generate considerable greenhouse gas (GHG) emissions, suggesting potential conflicts in terms of mitigation and adaptation policies. In particular, the introduction of a price on carbon may influence the extent to which new irrigation technologies are adopted. This study evaluated trade-offs between water savings, GHG emissions and economic gain associated with the conversion of a sprinkler (hand shift) irrigation system to a drip (trickle) irrigation system for a lettuce production system in the Lockyer Valley, one of the major vegetable producing regions in Australia. Surprisingly, instead of trade-offs, this study found positive synergies - a win-win situation. The conversion of the old hand-shift sprinkler irrigation system to a drip irrigation system resulted in significant water savings of almost 2 ML/ha, as well as an overall reduction in GHG emissions. Economic modelling, at a carbon price of $ 30/t CO(2)e, indicated that there was a net benefit of adoption of the drip irrigation system of about $ 4620/ML/year. We suggest priority should be given, in the implementation of on-farm infrastructure investment policy, to replacing older inefficient and energy-intensive sprinkler irrigation systems such as hand shift and roll-line. The findings of the study support the use of an integrated approach to avoid possible conflicts in designing national climate change mitigation and adaptation policies, both of which are being developed in Australia.
  • Authors:
    • Poole, M. L.
    • Rodriguez, L. C.
    • Dunlop, M. I. A.
    • Campbell, P. K.
    • Jovanovic, T.
    • Taylor, J. A.
    • Herr, A.
    • Crawford, D. F.
    • O'Connor, M. H.
    • May, B. M.
    • Raison, R. J.
    • O'Connell, D. A.
    • Farine, D. R.
    • Braid, A. L.
    • Kriticos, D.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 2
  • Year: 2012
  • Summary: We provide a quantitative assessment of the prospects for current and future biomass feedstocks for bioenergy in Australia, and associated estimates of the greenhouse gas (GHG) mitigation resulting from their use for production of biofuels or bioelectricity. National statistics were used to estimate current annual production from agricultural and forest production systems. Crop residues were estimated from grain production and harvest index. Wood production statistics and spatial modelling of forest growth were used to estimate quantities of pulpwood, in-forest residues, and wood processing residues. Possible new production systems for oil from algae and the oil-seed tree Pongamia pinnata, and of lignocellulosic biomass production from short-rotation coppiced eucalypt crops were also examined. The following constraints were applied to biomass production and use: avoiding clearing of native vegetation; minimizing impacts on domestic food security; retaining a portion of agricultural and forest residues to protect soil; and minimizing the impact on local processing industries by diverting only the export fraction of grains or pulpwood to bioenergy. We estimated that it would be physically possible to produce 9.6GLyr-1 of first generation ethanol from current production systems, replacing 6.5GLyr-1 of gasoline or 34% of current gasoline usage. Current production systems for waste oil, tallow and canola seed could produce 0.9GLyr-1 of biodiesel, or 4% of current diesel usage. Cellulosic biomass from current agricultural and forestry production systems (including biomass from hardwood plantations maturing by 2030) could produce 9.5GLyr-1 of ethanol, replacing 6.4GLyr-1 of gasoline, or ca. 34% of current consumption. The same lignocellulosic sources could instead provide 35TWhyr-1, or ca. 15% of current electricity production. New production systems using algae and P. pinnata could produce ca. 3.96 and 0.9GL biodieselyr-1, respectively. In combination, they could replace 4.2GLyr-1 of fossil diesel, or 23% of current usage. Short-rotation coppiced eucalypt crops could provide 4.3GLyr-1 of ethanol (2.9GLyr-1 replacement, or 15% of current gasoline use) or 20.2TWhyr-1 of electricity (9% of current generation). In total, first and second generation fuels from current and new production systems could mitigate 26MtCO2-e, which is 38% of road transport emissions and 5% of the national emissions. Second generation fuels from current and new production systems could mitigate 13MtCO2-e, which is 19% of road transport emissions and 2.4% of the national emissions lignocellulose from current and new production systems could mitigate 48MtCO2-e, which is 28% of electricity emissions and 9% of the national emissions. There are challenging sustainability issues to consider in the production of large amounts of feedstock for bioenergy in Australia. Bioenergy production can have either positive or negative impacts. Although only the export fraction of grains and sugar was used to estimate first generation biofuels so that domestic food security was not affected, it would have an impact on food supply elsewhere. Environmental impacts on soil, water and biodiversity can be significant because of the large land base involved, and the likely use of intensive harvest regimes. These require careful management. Social impacts could be significant if there were to be large-scale change in land use or management. In addition, although the economic considerations of feedstock production were not covered in this article, they will be the ultimate drivers of industry devlopment. They are uncertain and are highly dependent on government policies (e.g. the price on carbon, GHG mitigation and renewable energy targets, mandates for renewable fuels), the price of fossil oil, and the scale of the industry.
  • Authors:
    • Ward, P. R.
    • Cordingley, N.
    • Flower, K. C.
    • Weeks, C.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Cover crops have been successfully integrated into conservation agriculture systems in many parts of the world. They are primarily used to provide surface cover as well as to improve soil fertility and suppress weeds. Black oat (Avena strigosa Schreb.) is a widely used cereal cover crop with a rapid growth and high biomass production. It is being trialled as a cover crop for conservation agriculture systems in southwestern Australia, which has a Mediterranean climate with a short winter growing season and where terminal drought is common. Only one crop can be grown in a year and, as such, the long term benefits of including a cover crop in this system must outweigh the loss in income by not growing a cash crop. This study, which was part of a larger conservation agriculture cropping systems trial, examined the effect of different crop sequences, which included oat cover crops and grass pasture, on soil nitrogen mineralisation and weed control. A related paper in this Special Issue examined the effect of cover crops on the soil water balance. We hypothesised that the inclusion of high-biomass oat cover crops in a cereal-dominated cropping system would (i) result in less immobilisation of soil nitrogen compared with that of harvested cereals, and (ii) significantly improve the weed control. We show that soil N mineralisation following oat cover crops was similar to that following wheat and barley. Therefore, cash crops grown after oat cover crops would require similar levels of nitrogen to those grown after harvested cereals. Oat cover crops and grass pasture were found to be very effective in controlling weeds, even in continuous cereal rotations. Two consecutive years of cover crop were required for good annual ryegrass (Lolium rigidum Gaud.) control in a predominantly cereal rotation. Timing of when the cover crops were killed by herbicide was crucial for good weed control, as failure to prevent weed seed set resulted in significantly reduced weed control. Also, late killing of the cover crop reduced soil water storage. The inclusion of an oat cover crop in the rotation reduced the three-year average gross margin; however, the profitability of these crops needs to be evaluated over a longer period. To date, managed pasture, with herbicide control of weed seed set, appears to be a better option than oat cover crops because of the relatively low cost and increased soil water storage. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Hulugalle, N. R.
    • Ghadiri, H.
    • Weaver, T. B.
    • Harden, S.
  • Source: Chemosphere
  • Volume: 88
  • Issue: 3
  • Year: 2012
  • Summary: Organochlorine pesticides (OCPs) such as DDT and DDE have been detected in the surface 0.2 m of Vertisols in the lower Namoi Valley of north western New South Wales, Australia even though they have not been applied to crops since 1982. However, their presence in the deeper soil horizons has not been investigated. The objective of this study was to determine if OCPs were present to a depth of 1.2 m in Vertisols under irrigated cotton farming systems in the lower Namoi Valley of New South Wales. Soil was sampled from the 0-1.2 m depths in three sites, viz. the Australian Cotton Research Institute, ACRI, near Narrabri (149 degrees 36'E, 30 degrees 12'S), and two cotton farms near Wee Waa (149 degrees 27'E, 30 degrees 13'S) and Merah North (149 degrees 18'E, 30 degrees 12'S) in northern New South Wales, Australia. The OCPs detected and their metabolites were alpha-endo-sulfan, beta-endosulfan, endosulfan sulphate, DDD, DDE, DDT and endrin. The metabolite DDE, a breakdown product of DDT, was the most persistent OCP in all depths analysed. Endosulfan sulphate was the second most persistent followed by endrin > alpha-endosulfan > beta-endosulfan > DDT and DDD. DDT was sprayed extensively in the lower Namoi Valley up to the early 1980s and may explain the persistence of DDE in the majority of soil samples. Dicofol and Dieldrin. two OCPs previously undocumented in Vertisols were also detected. The movement of OCPs into the subsoil of Vertisols may occur when irrigation or rain transports soil colloids and organic matter via preferential flow systems into the deeper layers of a soil profile. Persistence of OCPs was closely correlated to soil organic carbon concentrations. The persistence in soil of OCP's applied to cotton crops grown more than two decades ago suggests that they could enter the food chain. Their presence at depths of 1.2 m suggests that they could move into groundwater that may eventually be used for domestic and stock consumption. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
  • Authors:
    • Orr, W.
    • Cooper, J.
    • Chataway, R.
    • Cowan, R.
  • Source: Animal Production Science
  • Volume: 51
  • Issue: 10
  • Year: 2011
  • Summary: Dairy farms located in the subtropical cereal belt of Australia rely on winter and summer cereal crops, rather than pastures, for their forage base. Crops are mostly established in tilled seedbeds and the system is vulnerable to fertility decline and water erosion, particularly over summer fallows. Field studies were conducted over 5 years on contrasting soil types, a Vertosol and Sodosol, in the 650-mm annual-rainfall zone to evaluate the benefits of a modified cropping program on forage productivity and the soil-resource base. Growing forage sorghum as a double-crop with oats increased total mean annual production over that of winter sole-crop systems by 40% and 100% on the Vertosol and Sodosol sites respectively. However, mean annual winter crop yield was halved and overall forage quality was lower. Ninety per cent of the variation in winter crop yield was attributable to fallow and in-crop rainfall. Replacing forage sorghum with the annual legume lablab reduced fertiliser nitrogen (N) requirements and increased forage N concentration, but reduced overall annual yield. Compared with sole-cropped oats, double-cropping reduced the risk of erosion by extending the duration of soil water deficits and increasing the time ground was under plant cover. When grown as a sole-crop, well fertilised forage sorghum achieved a mean annual cumulative yield of 9.64 and 6.05 t DM/ha on the Vertosol and Sodosol, respectively, being about twice that of sole-cropped oats. Forage sorghum established using zero-tillage practices and fertilised at 175 kg N/ha.crop achieved a significantly higher yield and forage N concentration than did the industry-standard forage sorghum (conventional tillage and 55 kg N/ha.crop) on the Vertosol but not on the Sodosol. On the Vertosol, mean annual yield increased from 5.65 to 9.64 t DM/ha (33 kg DM/kg N fertiliser applied above the base rate); the difference in the response between the two sites was attributed to soil type and fertiliser history. Changing both tillage practices and N-fertiliser rate had no affect on fallow water-storage efficiency but did improve fallow ground cover. When forage sorghum, grown as a sole crop, was replaced with lablab in 3 of the 5 years, overall forage N concentration increased significantly, and on the Vertosol, yield and soil nitrate-N reserves also increased significantly relative to industry-standard sorghum. All forage systems maintained or increased the concentration of soil nitrate-N (0-1.2-m soil layer) over the course of the study. Relative to sole-crop oats, alternative forage systems were generally beneficial to the concentration of surface-soil (0-0.1 m) organic carbon and systems that included sorghum showed most promise for increasing soil organic carbon concentration. We conclude that an emphasis on double- or summer sole-cropping rather than winter sole-cropping will advantage both farm productivity and the soil-resource base.
  • Authors:
    • Hoare, T.
  • Source: Wine and Viticulture Journal
  • Volume: 26
  • Issue: 3
  • Year: 2011
  • Summary: This paper describes the suitability of rolled cover crops (including oats, triticale and faba beans), white alyssum ( Lobularia maritima), saltbush ( Atriplex semibaccata and Enchylaena tomentosa) and chicory for cultivation with grape under the mid-row crop management system (MCS). The characteristics of vineyards suitable for MCS, and the beneficial effects of the aforementioned crops on vineyard profitability and productivity are covered.
  • Authors:
    • Weeks, A.
    • Hoffmann, A.
    • Tsitsilas, A.
    • Umina, P.
  • Source: Australian Journal of Entomology
  • Volume: 50
  • Issue: 1
  • Year: 2011
  • Summary: Non-crop vegetation adjacent to broad-acre pastures and crops can influence the abundance of invertebrate pests by promoting populations of beneficial natural enemies. However, characteristics of adjoining vegetation that consistently promote natural enemies are often unknown. Here we manipulate the height of grasses and herbaceous plants within windbreaks at five geographically separated sites in south-eastern Australia to examine the effects of on-ground vegetation structure on the abundance of pest mites and natural enemy complexes. Reducing the height and cover of vegetation across 2 years led to decreased numbers of predatory mites, predatory beetles and spiders within windbreaks and at sites 5 m from the windbreak edge within adjacent pastures. There was also an associated increase in numbers of pest earth mites, the redlegged earth mite ( Halotydeus destructor) and blue oat mites ( Penthaleus spp.). Similar findings were found in manipulative experiments under semifield conditions using microcosms. These results suggest that an increase in height and perhaps complexity of groundcover act to promote populations of beneficial natural enemies with potential suppression of pest mite species. These findings point to a simple way for increasing populations of beneficial invertebrate species at the farm scale that could contribute to integrated pest management programs.
  • Authors:
    • [Anonymous]
  • Source: Australian Cottongrower
  • Volume: 32
  • Issue: 5
  • Year: 2011
  • Summary: This issue is divided into 10 sections covering various aspects of the Australian cotton industry, such as production, irrigation and drainage, research and extension and processing and marketing. The various national and regional organizations and the companies that service the Australian cotton industry are also pointed out.