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This paper presents a comprehensive substance flow analysis (SFA) of phosphorus (P) for a six-year period (2008–13) in Gippsland, a key agricultural region of Australia with high economic and environmental significance. The analysis has revealed that around 71% (10,904 t) of the mean annual total inflow of P was stored in this region. This finding is different from other published regional scale SFAs, where more than 50% of the P in annual total inflow eventually left the region. Per capita P inflow in Gippsland is also found substantially higher compared to available SFAs. In Gippsland, the annual inflow of P primarily occurred as commercial fertilizer (66% or 10,263 t) and livestock feed (29% or 4443 t), and the outflow mainly occurred as livestock products (94% or 4181 t); while the majority (66% or 7218 t) of the P storage occurred in soils of the livestock farming area. A comparative analysis of the magnitude of P flow in different subsystems indicates that more than 80% of the annual total inflow, outflow, and storage of P in this region is associated with the livestock (mainly dairy and meat cattle) farming subsystem. For the Gippsland region as a whole and almost all subsystems, significant annual variations in the magnitudes of P inflow, outflow, storage and internal flow have been observed. Between 2008 and 2013, both the annual total inflow (mainly as commercial fertilizer) and the annual total storage (mainly in soils) of P in this region showed a substantial decrease (41% and 54% of the 2008 level, respectively), while the annual total outflow (mainly as livestock and crop products) remained nearly the same, indicating an improvement towards sustainable P management. Despite such a positive sign, there is still adequate room for improvement. This analysis indicates that over the study period, about 65,424 t P were accumulated (mainly as soil storage) that is approximately six times the mean annual P inflow as commercial fertilizer in this region; while approximately 3241 t P lost as soil erosion and runoff, indicating substantial adverse economic and environmental implications. Based on the findings of the current analysis, this paper outlines a wide range of policy and management interventions to reduce the downstream loss of P and other nutrients as well as the region's dependency on imported commercial fertilizers and grain based feed. This paper also presents new criteria for data quality analysis and a set of P concentration data of various materials that could be readily utilized in future SFAs of P at any geographical scale. This paper suggests that considering the inter-annual variations in P flow as assessed in this SFA, future research should focus on identifying the influence of socio-environmental, technological and political factors on the magnitude P flow in Gippsland. [ABSTRACT FROM AUTHOR]

The question addressed in this paper is whether the agronomic efficiency of cropping sequences can be improved in the northern grain zone of Australia. Analysis of whole systems over multiple seasons is particularly important in cropping regions such as Australia's northern grain zone, where farmers have the option of growing a variety of winter and summer crops and where fallowing is required to store water to safeguard yields of following crops. The study is based on a detailed longitudinal survey of the inputs and yields of 94 farmers' fields over 7 seasons. The Agricultural Production Systems Simulator (APSIM) was used to benchmark the 94 cropping sequences and to determine if the productivity of these cropping sequences can be improved through changed management, particularly of nitrogen nutrition and timely sowing of individual crops. Comparison of surveyed and simulated yields were then used to determine the yield gap that can be explained by factors unaccounted for in APSIM, i.e. biotic stresses such as weeds, pests and diseases or inadequate operational management. Using a generalised N response curve, data from the simulation analysis were plotted relative to a normalised input-output relationship to determine their position relative to an efficiency frontier representing the simulated production function. This analysis was conducted separately for both individual crops and for whole sequences in individual fields. The analysis of 193 individual crops showed that the average yield of 1.90t/ha was 65% of the simulated water and nitrogen-limited yield potential of 2.92t/ha. Investigation of nitrogen unlimited and early sowing management options revealed that there was relatively little yield advantage (0.15t/ha) to be gained from these management improvements. The remaining gap between observed yields and what the simulations suggest may be attributed to factors such as weeds, pests and diseases, sub-optimal operations or extreme weather events. Three production criteria were used to compare cropping sequences: (1) dollar income, (2) metabolisable energy yield, and (3) crude protein yields. While the income from 36% of the individual crops in the study was found to be more than 80% of their production frontier values, only 29% of whole cropping sequences achieved this benchmark. Similar results were achieved when crops and crop sequences were evaluated in terms of their metabolisable energy and crude protein yields. It is concluded that in order to increase the agronomic efficiency of cropping in Australia's northern grain zone, attention should be focussed on the intensity and configuration of cropping sequences and on the management of fallows in addition to the management of individual crops. [ABSTRACT FROM AUTHOR]

Abstract: Evaluating the potential scale of adoption of a technological innovation or management practice at the farm business scale can help gauge the potential size of an industry for the purposes of prioritising resources for research and development. In this paper we address the question of quantifying the potential area of adoption of a perennial pasture, lucerne (Medicago sativa L.), in dryland mixed farming systems in Australia. Lucerne pastures play a significant role in dryland farming systems in the wheat-sheep zone of southern and western Australia. While there are benefits of integrating lucerne into cropping systems there will inevitably be additional costs, and the scale of adoption of lucerne will depend largely on the increase in farm profit resulting from the introduction of lucerne. Whole-farm economic models of representative farms in the Australian wheat-sheep belt were used to determine the key drivers for the scale of adoption of lucerne. For a particular farming system the optimal area of lucerne which maximises whole-farm profit is found to depend on production, price and cost conditions. Generally, no more than 30% of a farm was allocated to lucerne according to those conditions and location of the farm. For most scenarios examined the response of profit was flat around the optimal area. This implies that lucerne could be grown on areas greater than the optimum, in order to reduce groundwater recharge (and thereby reduce the risk of dryland salinity), without greatly reducing whole-farm profit. The optimal area of lucerne in all regions was limited by the area of suitable soil types and proportion of lucerne in the most profitable lucerne-crop sequences. At all price levels assumed in this study lucerne remained as part of the optimal enterprise mix for all farm types examined. Lucerne productivity was also a major determinant of the optimal area of lucerne. The sensitivity of profit to changes in winter and/or summer production varied between regions and for different livestock enterprises. The differences were driven by the timing of energy demands and supply of feed in individual farming systems. In all regions the optimal area and profitability of lucerne varied with livestock enterprise. The analyses showed that changing from wool production to meat production enabled greater economic benefit to be realised from lucerne. This was consistent across farm types and demonstrated the value of lucerne as a source of high quality feed for finishing prime lambs in summer. The results of this study demonstrate that lucerne is profitable in a range of environments on a significant proportion of the farm area, but that this area is small relative to that required to significantly influence in its own right the environmental issue of salinity. [Copyright &y& Elsevier]

The seasonal break is a rainfall event that has traditionally initiated sowing and enabled plant establishment in Mediterranean-type environments. Despite its importance to crop production, neither the pattern of the seasonal break, nor the impact of recent autumn rainfall decline in eastern Australia on the pattern has been quantified at a national scale. Adaptive strategies to remove reliance on the seasonal break for crop establishment can include combinations of novel genotypes and innovative crop management. This paper (i) shows how seasonal changes may be altering the pattern of sowing opportunities across southern Australia, and (ii) evaluates the potential for adaptive management to deal with these changes using a case-study in southern Australia involving early, deep-sown wheat cultivars with long coleoptiles to reduce the dependence on the seasonal break for successful crop establishment. In the first part of the study, the timing of the seasonal break across the southern Australian cropping regions was determined using the sum of a 7-day rolling mean rainfall to evaporation ratio > 1 to trigger a sowing opportunity between 1 March and 30 July using long-term (1971–2018) gridded (0.05° × 0.05°) historical climate data. The relationship between early-season climatic conditions and adaptive management options was then evaluated using a growth chamber experiment and a field experiment in a Mediterranean-type environment to evaluate the factors leading to successful establishment of earlier deeply sown wheat cultivars with long coleoptiles. The analysis revealed spatial and seasonal variability with the earliest median seasonal break (27-March) in New South Wales (NSW) and Victoria, and the latest (3-June) in Western Australia (WA). The largest shift in seasonal break was a 17-day advance in the Mallee and Sandplain of WA, and an 11-day delay in Central NSW during the period 1990–2018. Evaluation of the factors controlling establishment of a long coleoptile wheat cultivar suggested that soil temperatures in the early sowing windows were unlikely to reduce coleoptile length, but seeding depth, soil type and water availability will play an important role on emergence. In summary, the shifts in the climatic conditions at the break of the growing season have not been the same across the southern cropping region. Adaptations for this climatic shift such as long-coleoptile, deep-sowing strategies for wheat show significant promise but careful consideration of soil factors is required to ensure success and to improve on-farm decision making regarding its use. [Display omitted] • Understanding recent climate shifts that influence the seasonal break underpins better decisions on GxM responses on-farm. • The seasonal break varied spatially in southern Australia, but it has seen shifts of −11 to 17 days in recent decades. • Long coleoptile wheat cultivars are a promising option for adaptation to this shift. • Soil temperatures during early sowing periods will not inhibit long coleoptiles, but soil moisture and texture were critical. • Combining knowledge of climatic shifts with successful crop emergence factors is critical to develop adaptive GxM strategies. [ABSTRACT FROM AUTHOR]

Mixed crop-livestock farms are important production systems worldwide and dominate Australia's broadacre agricultural regions. While integration of crops and livestock can offer many benefits, these are often intertwined and are hard to quantify explicitly. This paper set out to examine specifically the financial risk and return implications from operating a farm portfolio involving segregated crop and livestock enterprises considering both production variability and commodity price variability. Crop and livestock production from representative systems were simulated over 40 years at six locations spanning Australia's crop-livestock zone using coupled biophysical production simulation models, APSIM for cropping enterprises and GRAZPLAN for livestock enterprises. Time series of varying prices and costs for the same period were derived using historical data. Annual gross margins for each enterprise and different proportional land allocations to the farm were calculated either allowing both production and price to vary or keeping either constant at average values. At all locations the livestock enterprise had less downside risk than the cropping enterprises (as measured by conditional value at risk). Across both enterprises, the impact of production variability was greater than price variability at 5 of the 6 locations. Annual gross margins from the modelled crop and livestock enterprises were not well correlated with each other. Hence, even in the absence of biophysical interactions, the risk-efficient frontier included mixtures of crops and livestock enterprises at most sites. At two sites, a mix of 20–40% crop resulted in the lowest downside risk, while at other sites there was a clear trade-off between maximising farm returns and minimising risk across a range of crop-livestock mixtures. This is the first study to explicitly quantify and show across a diversity of environments in Australia's mixed farming systems that operating a mixture of even segregated crop and livestock enterprises in a farming business can help farmers optimise their risk-return trade-off. Similar risk mitigation benefits may be achieved through crop-livestock systems in other agricultural regions exposed to high climate and price variability. Unlabelled Image • Risk mitigation benefits of mixed farming examined across 6 locations in Australia. • Long-term variability in returns from crop and livestock enterprises were modelled. • Down-side risk was lower from livestock than cropping enterprises. • Annual returns from crop and livestock enterprises were weakly or not correlated. • Mixed farms were more risk efficient than those specialising on a single enterprise. [ABSTRACT FROM AUTHOR]

Lucerne (Medicago sativa L.) is valued by producers with integrated crop-livestock systems. The multiple benefits of periods of lucerne leys to either livestock or to crop production have been widely reported; however, the importance of managing lucerne leys to whole farm profit and production has not and is best suited to a whole of system modelling study. This paper reports a simulation study aimed at better understanding the mixed farming systems that include short-term (3-year) phases of lucerne: specifically, the effects of terminating lucerne leys at different times prior to cropping. Simulations of mixed farming systems with the same soil type, crop rotation and proportional land use were conducted along a rainfall transect in a temperate environment in south-eastern Australia. Spring versus summer termination of the lucerne ley prior to cropping in autumn were compared. Although farming systems where lucerne was terminated in spring had higher crop production (mostly because of increased N at sowing) than those where lucerne was terminated in summer, the opposite was true for livestock production. Livestock production was higher in systems with summer termination mostly because of higher ewe condition scores at mating. When these sometimes positive and sometimes negative effects were evaluated at the whole of farm scale, in cases except the low rainfall site, allowing the lucerne ley to grow as late as possible prior to cropping was the most profitable management strategy in medium to high rainfall systems as it resulted in more lambs that were sold at heavier weights and the systems were more profitable, less costly, more efficient and less risky than those where leys were terminated in spring. • The decision when to remove lucerne in leys requires a whole farm analysis. • Differences in removal dates at the farm level were small and yet significant. • Land in transition presents opportunities for increasing water and N use efficiency. • Summer termination of lucerne was overall more profitable, efficient and less risky. • Perennial legume pastures need to be seen as a whole-of-farm resource. [ABSTRACT FROM AUTHOR]