03 Tor Street

Toowoomba, Australia

03 Tor Street

Toowoomba, Australia
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Liu H.,University of Queensland | Crawford M.,03 Tor Street | Carvalhais L.C.,University of Queensland | Dang Y.P.,University of Queensland | And 2 more authors.
Geoderma | Year: 2016

Over half of the arable land in the northern grains region of Australia is managed using no-till (NT), a farming method which has improved crop yields and soil quality while reducing the input and labour costs. However, concerns have arisen among farmers over the control of weeds in continuous NT systems. An occasional targeted tillage operation (termed strategic tillage - ST) has been proposed as a management tool to reduce problem weed populations but may adversely influence soil properties and those of associated microbial communities. To assess the potential impacts of a ST operation on soil properties, a Grey Vertosol with fifteen years of NT in Northern New South Wales, Australia was tilled using either a chisel cultivator or disc chain on March 15th 2013 or on April 5th 2013. We hypothesised that ST using these minimal or low soil inversion implements at either timing would not adversely influence soil properties in the short-term (4-7weeks). The measured soil properties were soil volumetric moisture content (VMC), pH, bulk density (BD), electrical conductivity (EC), available phosphorus (P), soil organic carbon (SOC), microbial biomass carbon (MBC), metabolic activity (MA), genetic structures of bacterial communities and wheat yield (t ha-1). We found that ST with either a chisel cultivator or a disc chain has great potential to assist in weed management as it did not statistically influence crop productivity or the physical, chemical and biological properties of the soil, regardless of the tillage timing. © 2015 Elsevier B.V.

Potgieter A.B.,University of Queensland | Lobell D.B.,Stanford University | Hammer G.L.,University of Queensland | Jordan D.R.,University of Queensland | And 2 more authors.
Agricultural and Forest Meteorology | Year: 2016

Globally as well as nationally, food production is being exposed to increased climatic and market volatility. The trend in sorghum yield in Australia has been consistent and positive over the last 30 years, while yield trends globally for other cereals like wheat, maize and rice have slowed. Australia is of interest not only as a major exporter in world markets, but also because considerable research effort has been focused on developing crops and practices that help to reduce the risks of yield losses under drought conditions. This study examines sorghum and wheat yield trends over the previous three to four decades in Australia after realistically accounting for the effects of year-to-year climate variability. We quantified the yield trends within three distinct types of crop stress environments (i.e. DRY: ENVT1, MODERATE: ENVT2& WET: ENVT3). Overall trends in sorghum yields were 2.1% per year (44 kg/ha/year), which was nearly double that found for wheat (1.2% per year; 21 kg/ha/year). However, in dry environments, relative yield trends for sorghum were 3.6 times those for wheat, whereas in wet environments trends were similar. Likely technology and environmental factors underpinning these trends are discussed. © 2016 Elsevier B.V.

Hill J.,03 Tor Street | Redding M.,03 Tor Street | Pratt C.,03 Tor Street
Animal Production Science | Year: 2016

Land-applied manures produce nitrous oxide (N2O), a greenhouse gas (GHG). Land application can also result in ammonia (NH3) volatilisation, leading to indirect N2O emissions. Here, we summarise a glasshouse investigation into the potential for vermiculite, a clay with a high cation exchange capacity, to decrease N2O emissions from livestock manures (beef, pig, broiler, layer), as well as urea, applied to soils. Our hypothesis is that clays adsorb ammonium, thereby suppressing NH3 volatilisation and slowing N2O emission processes. We previously demonstrated the ability of clays to decrease emissions at the laboratory scale. In this glasshouse work, manure and urea application rates varied between 50 and 150 kg nitrogen (N)/ha. Clay:manure ratios ranged from 1:10 to 1:1 (dry weight basis). In the 1-year trial, the above-mentioned N sources were incorporated with vermiculite in 1 L pots containing Sodosol and Ferrosol growing a model pasture (Pennisetum clandestinum or kikuyu grass). Gas emissions were measured periodically by placing the pots in gas-tight bags connected to real-time continuous gas analysers. The vermiculite achieved significant (P ≤ 0.05) and substantial decreases in N2O emissions across all N sources (70% on average). We are currently testing the technology at the field scale; which is showing promising emission decreases (∼50%) as well as increases (∼20%) in dry matter yields. This technology clearly has merit as an effective GHG mitigation strategy, with potential associated agronomic benefits, although it needs to be verified by a cost-benefit analysis. © CSIRO 2016.

Liu H.,University of Queensland | Carvalhais L.C.,University of Queensland | Carvalhais L.C.,Present address Sugar Research Australia | Crawford M.,03 Tor Street | And 3 more authors.
Biology and Fertility of Soils | Year: 2016

Continuous no-till (NT) farming is widely practiced in Australia, but it is prone to weed infestation. Strategic tillage (ST) can be used to effectively control weeds; however, it is unclear whether ST influences soil microbial properties. We investigated whether one- or two-time tillage events using a chisel plough influence the soil microbial properties of an acidic Solonetz with 19-year NT management. Soil samples were collected from 0–10 and 10–20 cm soil depths, 1 year post-ST after a chickpea crop. Microbial biomass C (MBC) and N (MBN), community-level physiological profiling (CLPP, MicroResp™) and fluorescein diacetate as an indicator of total microbial activity (TMA) were determined in soil. The composition of soil microbial communities was profiled using terminal reaction fragment length polymorphism (T-RFLP) and 16S rRNA sequencing. Detection and DNA-based quantitation of ChitinaseA, nifH, amoA, narG, nirK and nosZ genes were used to assess ST effects on soil C and N cycling. Our results show that one- and two-time chisel did not change soil MBC/MBN, TMA or CLPP. Likewise, ST did not change the composition of soil microbial communities and the abundance of genes encoding enzymes involved in key steps of C and N reactions at either soil depth. However, one-time chisel increased relative abundance of Acidobacteria RB41 and Acidobacteria iii1-15, and two-time chisel slightly increased the average C utilisation, both at 10–20 cm soil depth. This suggests that even after a cropping season of chickpea, ST effects on soil microbial properties of the NT Solonetz were negligible. One- and two-time chisel could potentially address the issues associated with long-term NT without impacting overall soil microbial properties. © 2016 Springer-Verlag Berlin Heidelberg

Miyake S.,University of Queensland | Smith C.,University of Queensland | Peterson A.,University of Queensland | McAlpine C.,University of Queensland | And 2 more authors.
Agricultural Systems | Year: 2015

Land use change effects have emerged as an important area of global bioenergy sustainability policy and research. 'Underutilised agricultural land' has been previously proposed as a potential option for future bioenergy feedstock production that may minimise the environmental and social challenges of land use change. However, this has not been well tested to date. Our research aims to evaluate whether conversion of these lands to selected bioenergy crops can lead to favourable environmental outcomes for eight indicators related to water quantity and quality, and terrestrial biodiversity. A spatially explicit evaluation framework based on GIS was developed to quantify the environmental effects of land use change. The land use change scenarios, established in a case study region in subtropical Queensland, Australia, were for the production of Pongamia and two native eucalypt species (Spotted gum and Chinchilla white gum) on (i) existing 'underutilised' open grazing areas, (ii) existing 'underutilised' forested grazing areas, and (iii) all available 'underutilised agricultural land' in the case study catchment, under both low and high management intensity. We found that environmental benefits can be gained in scenarios where (i) open grazing areas (e.g., pastures) were used; (ii) native woody perennial bioenergy crops were planted; and (iii) the new plantations were under low management intensity. Other scenarios resulted in reduced environmental outcomes. The results flagged the importance of careful planning and management strategies, and the need for future bioenergy policy to provide more detailed prescriptions concerning land use planning and management if 'underutilised agricultural lands' are used for future bioenergy crop production. © 2015 Elsevier B.V.

Dang A.,03 Tor Street | Dang A.,University of Southern Queensland | Silburn M.,03 Tor Street | Silburn M.,University of Southern Queensland | And 2 more authors.
Journal of Agricultural and Food Chemistry | Year: 2016

Herbicides are often applied to crop residues, but their fate has not been well studied. We measured herbicide washoff from sugar cane trash during simulated rainfall, at 1, 8, and 40 days after spraying (DAS), to provide insight into herbicide fate and for use in modeling. Herbicides included are commonly used in the sugar industry, either in Australia or in Brazil. Concentrations of all herbicides and applied Br tracer in washoff declined exponentially over time. The rate of washoff during rainfall declined with increasing DAS. Cumulative washoff as a function of rainfall was similar for most herbicides, although the most soluble herbicides did have more rapid washoff. Some but not all herbicides became more resistant to washoff with increasing DAS. Of the total mass washed off, 80% washed off in the first 30 mm (∼40 min) of rainfall for most herbicides. Little herbicide remained on the trash after rainfall, implying nearly complete washoff. © 2016 American Chemical Society.

Silburn D.M.,03 Tor Street | Silburn D.M.,University of Southern Queensland | Foley J.L.,03 Tor Street | Biggs A.J.W.,03 Tor Street | And 2 more authors.
Crop and Pasture Science | Year: 2013

The Australian cotton industry and governments have funded research into the deep-drainage component of the soil-water balance for several decades. Cotton is dominantly grown in the northern Murray-Darling and Fitzroy Basins, using furrow irrigation on cracking clays. Previously, it was held that furrow irrigation on cracking clays was inherently efficient and there was little deep drainage. This has been shown to be simplistic and generally incorrect. This paper reviews global and northern Australian deep-drainage studies in irrigation, generally at point-or paddock-scale, and the consequences of deep drainage. For furrow-irrigated fields in Australia, key findings are as follows. (i) Deep drainage varies considerably depending on soil properties and irrigation management, and is not necessarily 'very small'. Historically, values of 100-250mm year-1 were typical, with 3-900mm year-1 observed, until water shortage in the 2000s and continued research and extension focussed attention on water-use efficiency (WUE). (ii) More recently, values of 50-100mm year-1 have been observed, with no deep drainage in drier years; these levels are lower than global values. (iii) Optimisation (flow rate, field length, cut-off time) of furrow irrigation can at least halve deep drainage. (iv) Cotton is grown on soils with a wide range in texture, sodicity and structure. (v) Deep drainage is moderately to strongly related to total rainfall plus irrigation, as it is globally. (vi) A leaching fraction, to avoid salt build-up in the soil profile, is only needed for irrigation where more saline water is used. Drainage from rainfall often provides an adequate leaching fraction. (vii) Near-saturated conditions occur for at least 2-6m under irrigated fields, whereas profiles are dry under native vegetation in the same landscapes. (viii) Deep drainage leachate is typically saline and not a source of good quality groundwater recharge. Large losses of nitrate also occur in deep drainage. The consequences of deep drainage for groundwater and salinity are different where underlying groundwater can be used for pumping (fresh water, high yield; e.g. Condamine alluvia) and where it cannot (saline water or low yield; e.g. Border Rivers alluvia). Continuing improvements in WUE are needed to ensure long-term sustainability of irrigated cropping industries. Globally there is great potential for increased production using existing water supplies, given deep drainage of 10-25% of water delivered to fields and WUE of <50%. Future research priorities are to further characterise water movement through the unsaturated zone and the consequences of deep drainage. © 2013 CSIRO.

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