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Context: The winter feed gap is a common problem for livestock grazing systems worldwide, and changes to climate have made these deficits more unpredictable and extreme. Dual-purpose crops are an important tool in many southern Australian mixed crop–livestock systems to help fill the winter feed gap. Providing more reliable feed over winter can remove feed constraints and allow for earlier lambing in autumn with potential whole-farm system benefits. Aims: We simulated a whole-farm livestock enterprise in the Agricultural Production Systems Simulator (APSIM) to examine the implications of spring- and autumn-lambing systems relying on a standard pasture-only feedbase compared with a farm where 25% of its grazed area is allocated to dual-purpose crops. Methods: Twelve simulations were run across four locations in New South Wales, Australia, that varied in climatic conditions (both rainfall total and distribution) including two lambing systems (spring vs autumn) × two feedbase types (100% pasture vs 75% pasture and 25% dual-purpose crops) × three stocking densities. Key results: For autumn-lambing systems, integrating dual-purpose crops helped to fill the winter feed gap and reduced supplement demand on average by ~28% compared with a pasture-only system. Compared with the standard pasture-only spring-lambing system, integrating dual-purpose crops into spring- and autumn-lambing systems more than doubled gross margin returns due to economic grain yield and lower supplement demand. A shift from spring- to autumn-lambing facilitated by dual-purpose crops also led to better reproductive performance of ewes in the subsequent year. In higher-rainfall, cooler environments, autumn-lambing systems with dual-purpose crops had the highest system gross margins, lowest economic risk and allowed for a safe increase in stocking density. In lower-rainfall, warmer environments, integration of dual-purpose crops into spring-lambing systems returned marginally higher gross margins than for the autumn-lambing system, but differences were less apparent at high stocking density. In lower-rainfall environments, dual-purpose crops helped to mitigate some of the economic risk, but the benefits were less clear. Conclusions: We show dual-purpose crops can help fill the winter feed gap and support earlier lambing in autumn across a range of environments, especially in higher-rainfall cooler environments, with significant improvements in total farm gross margins. Implications: Integrating dual-purpose crops will enable farmers to change their livestock system to mitigate their risks, reduce supplementary feeding and capitalise on other potential benefits, such as improved marketing and avoiding animal health problems. Whole-farm simulation modelling suggests that integrating dual-purpose crops of wheat and canola to 25% of the farm decreases the winter feed gap and facilitates autumn-lambing systems across environments. Spring- and autumn-lambing systems with dual-purpose crops achieved more than double the farm gross margins compared with the standard spring-lambing, pasture-only system. In higher-rainfall, cooler environments, autumn-lambing systems with dual-purpose crops returned higher gross margins due to grain production and lower supplement demand, but in lower-rainfall, warmer environments, spring-lambing systems were still more profitable. [ABSTRACT FROM AUTHOR]

As a rainfed, short-season crop, mungbean is a particularly attractive summer rotation option for Australian farmers, but the rate of mungbean adoption in Australia is low due to its high yield instability. A lack of research conducted on modern mungbean in Australia has hindered farmers' ability to understand how to best manage the crop and close the yield gap. The aim of this study was to provide recommendations for optimal sowing windows (balancing maximum yield potential with minimum risk—i.e. instability and crop failure). We simulated 60 years of growing mungbean at 180 different sowing times, four different initial soil water levels and at seven sites across Queensland and New South Wales using the new Agricultural Production Systems sIMulator Next Generation (APSIM NextGen) Mungbean model. We then calculated the impact of sowing date on mungbean water use efficiency and on the soil water deficit for the subsequent crop in the rotation. Higher initial soil water levels decreased risk (instability and failure) at all sites. Arid sites with high evaporative demand had optimal sowing windows later (February) in the growing season. More temperate sites yielded better with higher levels of stability when sown between November and January. Sowing in September/October is not recommended in any site as it coincided with low yield stability and water use efficiency. Not all sites had a clear optimal sowing window. We conclude, therefore, that in some environments, sowing time can only marginally reduce risks in growing mungbean. We identified optimal sowing window that can reduce risks of a failed crop by 20 % and increase stability without losing yield potential. The timing of the optimal sowing window for a given site appears to be influenced by avoiding periods with high evaporative demand during the reproductive phase. Modelling has been critical for exploring the trade-offs between maximizing and stabilizing mungbean yields over a wide range of environments and growing seasons to determine the optimal sowing windows across the main growing environments in Australia. • Optimal sowing windows were identified for mungbean in Australia. • Aridity and Vapor Pressure Deficit influenced the timing of optimal sowing windows. • Spring sowing corresponds to high yield instability and low water use efficiency. [ABSTRACT FROM AUTHOR]