Water scarcity in southern Australia and an imperative to develop regional economies have combined to renew focus on the potential for irrigated agricultural development in Australia’s largely undeveloped and sparsely populated north. More than 2 billion potential dam sites across northern Australia (an area of ~3 million km2) were assessed in a consistent and objective manner, using the DamSite model, in the largest comprehensive assessment of large dams undertaken globally. Simultaneous consideration was given to large dams and their proximity to land physically suited to the development of irrigated cropping and horticulture. We did not consider regulatory and land-ownership limitations on irrigation and dam development or social, environmental and economic considerations. Although these factors do and will constrain water and agricultural development in northern Australia, each requires a site-specific analysis, and these factors can potentially change with time. Physical resources (soil, surface water, and topography suitable for large, in-stream dams) sufficient to support ~1.84 Mha of irrigated agriculture exist in northern Australia. This would require use of the entire yield from eight existing dams (including the Burdekin Falls and Ord River dams) and the construction of 117 new dams. A more financially attractive option could involve using water from 85 large dams (eight existing and 77 new dams) and a large number of reregulating structures (e.g. weirs) to irrigate 1.34 Mha of land suitable for irrigated agriculture. If realised, this would result in a ~50% increase in Australia’s area under irrigation. Approximately 50% of the potential 1.34 Mha of irrigated land in northern Australia (~670 000 ha) could be irrigated with ~20 of the more promising large dams, highlighting the declining marginal returns to dam construction and the benefits of strategic land and water resource planning. In reality, a range of regulatory, political and socio-economic factors will considerably constrain the upper physical limit to dam and irrigation development stated in this paper. They may also inevitably result in major developments occurring over longer timeframes than dam and irrigation developments of comparable scale in southern Australia during the 20th Century. Alternative sources of water (e.g. groundwater, wetlands, waterholes) and water storage (e.g. gully dams, ringtanks, managed aquifer recharge) are physically capable of supplying smaller volumes of water than large dams, although each may have important roles to play in maximising the cost-effectiveness of water supply in northern Australia.

Australia's agriculture industry, particularly in the north, is characterised by supply chains of long travel distances, often in excess of 2500 km and costing up to 35% of farm gate price. Such travel distances increase the vulnerability of the industry to climatic variability and extreme events. Infrastructure investments in roads, bridges, processors and storage, along with changes in policy, have the potential to substantially reduce costs and increase resilience of the agriculture industries. In this paper, we outline the model, TRAnsport Network Strategic Investment Tool (TRANSIT) which is based on ArcGIS, and utilizes the Origin to Destination Cost Matrix solver within the Network Analyst toolkit. TRANSIT estimates the transport costs for all movements between enterprises, accommodating road conditions, vehicle types, vehicle access restrictions and regulatory requirements. TRANSIT was applied to the northern Australia livestock industry, consisting of 12 million cattle across 10,000 enterprises and 89,000 unique trips between these enterprises. Its ability to estimate the transport benefits from road upgrades, new processing facilities and biosecurity changes are shown using three priority case studies identified by industry and government. (C) 2015 Elsevier B.V. All rights reserved.

On-ground investment in developing northern Australia's agriculture has not fully matched the level of on-going interest in the subject. On-ground investment requires that both investors and regulators have confidence in resource availability; uncertainty inevitably leads regulators to make conservative resource allocation decisions which, in turn, erode investor confidence. One way of increasing the confidence of investors and regulators is to provide information at a finer scale than is currently available. In January 2012 the Office of Northern Australia commissioned CSIRO to undertake a comprehensive agricultural assessment of the Flinders and the Gilbert catchments in the gulf region of northern Australia, an area two thirds the size of Victoria, and to do so in less than 2 years. This paper provides an overview of the findings of the Assessment and highlights the development of new methods for the rapid acquisition of data in vast and remote landscapes, such as northern Australia, and for quantifying uncertainty in soil parameter and hydrological predictions. It was found that, despite their close proximity, the Flinders and the Gilbert catchments varied considerably, highlighting that northern Australia is not one homogenous area and that to properly understand the scale and nature of development opportunities - and the risks that attend them - a detailed understanding of catchment resources is necessary. For the Flinders catchment it was found that farm scale off-stream storages could enable 10,000 to 20,000 ha of irrigation in 70-80% of years. For the Gilbert catchment it was found that in-stream dams could enable 20,000 to 30,000 ha of irrigation in 85% of years. Significant water use would amplify the ecological challenges of the dry years but at these scales of development has a moderate impact in the 'normal' and wet years.

The early stages of onshore gas development involve real and perceived uncertainty, each stimulating community demand for information and engagement with decision makers in government and industry. In response to this demand, the Department of Mines and Petroleum, APPEA, and CSIRO jointly hosted a workshop in Dongara in October 2012. Its purpose was to inform government and industry about community expectations for information provision and community engagement. Insights were gained by asking participants five main questions: What are your concerns and interests about onshore gas development? What are the issues that are important to you? How would you like to get information about issues of concern? How and with whom would you like to engage to identify future needs? What support would that require? The community articulated its demand for more information about the concerns and interests identified; it also expressed a strong preference for information from sources without regulatory or industry development roles. A range of different methods for providing information were identified, including physical and digital material, as well as interactive workshops and experiential farm walks. Participants expressed their expectation of greater engagement with decision makers from industry and government, as this would enhance the capacity for relevant local knowledge to inform industry regulation and management. To best reach their target audiences, engagement methods and approaches should be tailored to meet the needs of different sectors of the community.

Hydraulic fracturing has been the focal point of widespread and global public debate.While the resources sector typically sees hydraulic fracturing as a low-risk method for accessing the coal seam and shale gas reserves required to meet growing public demand for energy, some in the community perceive it as an unmanageable and unacceptable risk.Concerns about hydraulic fracturing and the coal seam gas (CSG) industry include the health impacts of chemicals used, contamination of water supplies from fugitive gas after hydraulic fracturing, equity of land and water access, long term impacts on groundwater, and the full life cycle emission of greenhouse gases from CSG compared to that of coal.This paper highlights the main psychological drivers behind some of these concerns and a possible approach to effectively address them.

Phosphorus (P) deficiency has been shown to decrease accumulated intercepted solar radiation (RIcum) for sweet corn and in this paper the effects on radiation use efficiency (RUE) and leaf photosynthetic rate at 2000 mu mol m(-2) s(-1) PPFD (P-2000) are examined. Data from two consecutive field experiments on a low P site at Lincoln, New Zealand, were analyzed. In the first experiment (2001/2002) 0, 50,100,150 or 200 kg P ha(-1) was applied to sweet corn followed by an additional 0, 0, 10, 20 or 40 kg P ha(-1) in 2002/2003 applied to the same plots. Thus, total P applications were 0, 50, 110, 170, or 240 kg P ha(-1).There were no differences in RUE between P treatments but RUE changed with crop ontogeny. The RUE was 0.66 g MJ(-1) before each crop had 10 fully expanded leaves and RUE was 1.34 9 MJ(-1) after this. The cause of this difference between development stages was unclear, but it was not related to air temperature. In contrast to RUE, there were clear differences in P-2000 due to differences in specific leaf phosphorus (SLP). At a SLP of 0.12 g P m(-2) or greater, P-2000 was a constant value of 34 mu mol CO2 m(-2) s(-1). When SLP was less than 0.12 g P m(-2) P-2000 was reduced. The differences in P-2000 between P treatments occurred when the plants were young (<= 10 fully expanded leaves) and after this, SLP of all leaves exceeded 0.12 g P m(-2) and there were no differences in P-2000. These early leaves were unimportant in determining crop RUE but are likely to have been important in establishing the hierarchies that led to the changes in RIcum reported previously. These results demonstrate the importance of an adequate supply of P early in crop growth. (C) 2008 Elsevier B.V. All rights reserved.

Insufficient phosphorus (P) availability decreases the yield of Zea mays, particularly for sweet corn crops grown in cool environments. This research examined the mechanisms of yield reductions with initial emphasis on canopy expansion processes that affect the interception of solar radiation. Experiments in two consecutive seasons (2001/2002 and 2002/2003) were grown at a low P site (Olsen P = 6 mu g ml(-1)) at Lincoln, New Zealand. Each experiment contained five rates of P application. In 2001/2002 rates of 0, 50, 100, 150, or 200 kg P ha(-1) were applied. In 2002/2003 an additional 0, 0, 10, 20 or 40 kg P ha(-1) was applied to the same plots producing total P treatments of 0, 50, 110, 170 or 240 kg P ha(-1) summed over the two seasons.When P availability was limited (0 or 50 kg P ha(-1)) the rates of leaf tip and fully expanded leaf appearance were slower in both seasons. Phyllochrons (degrees Cd leaf tip(-1)) were similar to 5 degrees Cd longer in crops that received 0 kg P ha(-1) than those fertilised with >= 100 kg P ha(-1). The area of individual leaves was also reduced by low P inputs but the ranking of leaf area by main stem leaf position was conservative. The leaf area of the largest leaf of the unfertilised crops was at least 22% less than the maximum measured leaf area in both seasons. In contrast, P fertiliser application had no effect on leaf senescence.The rate of leaf appearance per plant, individual leaf area and plant population were integrated to calculate green leaf area index (GLAI) and to estimate accumulated radiation interception (RIcum) for these crops. The total RIcum throughout the season in the unfertilised crops was 12-28% less than for those crops that received >= 100 kg P ha(-1) in both seasons. This difference partly explained the differences in crop biomass production in response to P availability. A sensitivity analysis showed that RIcum was equally sensitive to changes of the rate of leaf appearance and the area of individual leaves in response to P supply. Both processes need to be incorporated in mechanistic models of P effects on Z. mays which can be used to design efficient P fertiliser strategies. (C) 2008 Elsevier B.V. All rights reserved.

Sweet corn kernel yield responds to phosphorous (P) supply, but whether the response is mediated through a general increase in crop biomass or increased partitioning to kernels is unclear. Furthermore, changes in ear quality (ear length, diameter, and unfilled tip length) may also result from changes in crop biomass or partitioning. This research quantifies the partitioning between vegetative and reproductive (including ear quality) components for field-grown sweet corn crops, with a range of total biomass yield resulting from different rates of P fertiliser. To do this, ‘Challenger’ sweet corn was sown in 2 consecutive seasons (2001–02 and 2002–03) on a low-P site (Olsen P = 6.5 μg/g) at Lincoln, Canterbury, New Zealand. Five rates of P fertiliser were applied in each season. In 2001–02, 0, 50, 100, 150, or 200 kg P/ha was applied. These were followed by an additional 0, 0, 10, 20, and 40 kg P/ha in 2002–03. This gave a fertiliser range of 0–240 kg P/ha over 2 years. The resulting range in crop biomass (9.7–16.7 t DM/ha) was conservatively partitioned to vegetative (45%), rachis and husk leaf (32%), and kernel (23%) fractions, indicating that kernel yield responses were solely related to changes in crop biomass. The number of harvestable ears increased by 0.39 ears/m2 for every 1 t DM/ha increase in crop biomass. Similarly, ear quality was related to the kernel yield per primary ear. Specifically, the unfilled tip length decreased by 3.1 mm and individual kernel dry mass increased by 16 mg for every 10 g increase in kernel DM per ear. These results show that P fertiliser should be applied at optimum rates (in these experiments ≥100 kg P/ha) to maximise sweet corn crop biomass, which in turn will lead to maximum kernel yield and ear quality. The conservative partitioning of crop biomass suggests that other agronomic factors that increase total biomass production are likely to have a similar effect on crop yields.

Over the last 30 years, significant resources have been devoted to the development of computer-based decision support systems (DSS), usually in the belief that they were capturing, assimilating and delivering information that could help farmers to better manage their farms. The accumulated evidence suggests that this belief was largely misguided - most DSS have 'failed' in the agricultural market place. Despite this, many scientists continue to develop and attempt to deploy DSS that are intended to help farmers make management decisions. Here we examine aspects of the 'success' or 'failure' of three DSS with the aim of drawing from the experience some guidelines that may help in the development and deployment of future DSS. We don't see DSS as a lost cause, provided that scientists learn hard-won lessons from their collective achievements and failures. These include recognizing: (1) the need for comprehensive marketing information to inform the process of DSS conception and delivery rather than just the more usual autopsy; (2) that there are almost invariably other, perhaps more effective, methods for acquiring and transmitting the knowledge embodied in a DSS; (3) that what appear to be technical and quantitative management 'problems' often involve social, qualitative and subjective processes and 'solutions' that DSS are not well-equipped to consider; (4) that DSS are usually best accepted when they seek to enhance rather than replace farmers' existing decision making processes, making those that help to understand 'how things work' generally better accepted than those that present 'optimized' solutions. Further lessons are examined.

The response of sweet corn canopy development to timing and severity of water deficit was determined in an experiment using a mobile rainshelter. Six irrigation treatments were applied such that plots experienced: (1) no water deficit; (2) full water deficit; (3) moderate pre-silking deficit; (4) severe pre-silking deficit; (5) moderate post-silking deficit; or (6) severe post-silking deficit. Soil moisture content profiles were measured using neutron moisture probes and water deficit was quantified using the concept of 'potential soil moisture deficit' (Dp), which was calculated from climatic data. Water deficit reduced leaf area, and the effect varied depending on its timing and severity. Early water deficit reduced the rate of leaf expansion (but not duration of expansion) and, consequently, the maximum area of individual leaves; it therefore reduced the maximum leaf area index (LAI). Moderate post-silking water deficit did not significantly reduce maximum LAI, but it hastened leaf senescence. Severe water deficit late in crop growth reduced canopy development by decreasing maximum LAI and advancing leaf senescence. A model was developed which accounted for these effects. Two measures of Dp were defined which related to both short-term transient responses and those integrated over longer times. The model made it possible to simply and mechanistically describe the effects of water deficit on canopy development.

The effects of row spacing and plant population on maize yield and quality (bulk density, thousand kernel mass) were examined in three different environments (Waikato, Hawke's Bay and Manawatu). Two maize hybrids differing in maturity (hyb. 36H36, medium season and hyb. Raissa, short season) were grown at seven populations (70, 80, 90, 100, 110, 120 and 140 thousand plants/ha) and a range of row spacings. In the Waikato and Manawatu, crops were grown at standard (75 cm) and narrow (50 cm) rows. A 25 cm row spacing was added in Hawke's Bay. Every combination of these treatments was applied in a fully randomised design at each location. In general, the influence of row spacing on maize yield and quality was minimal and inconsistent. By contrast, the effects of population on yield and quality were significant and generally predictable. There was no significant effect of row spacing on any component of yield or quality for crops grown at 'normal' plant populations (ea 90,000 plants/ha). Consequently, the results from this limited set of experiments suggest that, at the current 'standard' population, there is no benefit from narrow (25 or 50 cm rows) compared with standard (75 cm) row spacing. By contrast, increasing the population significantly increased yield (by an average 7% for every additional 10,000 plants/ha) up to a plateau that usually occurred at ea 120,000 plants/ha. Thousand kernel mass consistently declined with increased population (by about 1 g for every additional 10,000 plants/ha) whereas the response of bulk density to population was less predictable, and varied from nil to negative. There was consequently only a very small probability of economic benefit associated with narrower rows, but considerable scope for improving profitability by $100-1000/ha through adopting higher than current plant populations.

The effects of sowing time on maize yield were examined: 1) to test the hypothesis that maximum yield occurs when the time of maximum green leaf area index (GLAI) coincides most closely with the time of maximum incident solar radiation (SR) and 2) to use the results of this test to develop simple rules of thumb to help growers optimise maize sowing time. Two maize hybrids which differed in time required for maturation, short season (Elita) and long season (32H39) were sown at approximately fortnightly intervals from 21 September 1999 to 20 January 2000, giving a total of ten sowing times. Canopy development was monitored weekly and grain yield was measured at maturity. For the long season hybrid, grain yield was maximised when there was close synchrony between times of maximum GLAI and SR. For long season hybrids in New Zealand, maximum yield will occur when maximum GLAI occurs close to Christmas Day. For the short season hybrid, grain yield was maximised when maximum GLAI occurred 11 days after peak SR. We conclude that, for short season hybrids in New Zealand, maximum yield will occur when maximum GLAI occurs around New Year's Day.

The last 20 years of agricultural research have seen significant advances in what may be termed 'basic' knowledge of crop management. The development of simple to use mechanistic crop models has enabled scientists and growers to identify and exploit combinations of location, genotype and sowing time to maximise yield potential. While spectacular success has been evident for some crops, the advances have been less obvious in others. Historically, decision support systems for potato growers have concentrated on pest and disease management and have ignored the impact of simple management decisions on growth and yield. This is problematic, not just because there is a dearth of information on the control of yield but because, without a reliable estimate of yield, pest and disease models are unable to provide information about the economic impact of management decisions. Here we present results from an experiment designed to be the first step in constructing a model of potato growth and yield for New Zealand conditions. The growth of tubers of cvs. Fianna and Russet Burbank is examined and related to canopy development and radiation interception.

Economic and environmental concerns have increased the need for quantitative advice on fertilizer rates. In addition, it would aid researchers to be able to estimate the degree to which nutrient availability is affecting yield in a wide variety of field experiments. All of these needs can, in principle, be addressed using the new PARJIB model. PARJIB retains the functional simplicity of much earlier analytical models of crop responses to soil test values and fertiliser application rates. However, in a key departure from previous approaches, response to scaled nutrient supply indices is dictated by the potential yield adjusted for plant population and water stress. The version currently being evaluated simulates responses to supply of N, P, K and Mg, varying either singly or in combination. We have calibrated the model for sweet corn, carrots, and snap bean crops grown under temperate conditions in a wide range of soils. Simulated yields agreed well with observed values; the root mean square error was 8% to 13%, and regressions of observed against simulated yields passed through the origin with slopes that were not significantly different from 1. After calibration, the model predicted strong interactions between nutrient supply, plant population and water stress. PARJIB appears to have substantial potential to improve nutrient management for horticultural crops.

The effect of soil temperature on maize phenology, canopy development, biomass and yield was examined by applying three treatments that altered soil temperature with only minimal impact on air temperature. Our aim was to determine: (1) the extent to which soil temperature controls rate of development while the meristem is underground, and (2) the effect of soil temperature on subsequent development and growth. Soil temperature controlled the rate of development while the meristem was underground, which was until six fully expanded leaves had appeared. This was shown clearly by the fact that only when soil temperature was included in the calculation of thermal time was it possible to describe rate of development independent of soil temperature treatment. Biomass and yield increased by 21% between the coolest and warmest soil temperature treatments. This occurred because increased soil temperature accelerated the rates of leaf tip appearance and full leaf expansion, enabling the crop to more rapidly attain maximum green leaf area index. This enabled a better synchrony between time of peak radiation interception and peak radiation incidence. At a time of decreasing photoperiod, this enabled crops grown in warmer soil to intercept more radiation and to accumulate more biomass and yield. The extent to which soil temperature affects yield will therefore vary with sowing time and latitude of growth location.