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Integrating cover crop mixtures into dryland crop-fallow rotations may foster ecological intensification by enhancing ecosystem function multifunctionality compared with conventional fallows and monoculture cover crops. However, the expression of functional traits in cover crop mixtures is influenced by arrays of agronomic and environmental filters that differently influence cover crop performance. To (1) determine the identity and diversity effects of different cover crop functional types on ecosystem functions and trade-offs, and (2) determine the optimal cover crop mixture that maximizes ecosystem function multifunctionality in a subtropical dryland environment. Using three-site-year field experiments, we assessed if cover crop mixtures enhanced ecosystem function multifunctionality (MF) above that of monoculture cover crops and conventional fallow. We measured a range of ecosystem functions as indicators of three major ecosystem service categories: 1) provisioning services (biomass production, cash crop yield, and profitability); 2) supporting services (weed suppression, soil active carbon accrual, soil aggregate distribution, nitrogen (N) mineralization, N supply, and N retention); and 3) regulating services (parasitic nematode suppression, promotion of free-living nematodes, soil respiration, and soil water conservation). We found greater suite of ecosystem functions following mixture cover crops compared to monocultures, likely due to synergistic trait combinations that increased ecosystem function multifunctionality. The legume and forage brassica monocultures had consistently low multifunctionality (MF < 0.5). The oat:legume mixture resulted in the highest multifunctionality (MF > 0.5), driven by moderate water use and aboveground biomass production, and high groundcover residency, thus favouring higher cash crop yields and system profitability. They also generated overall improvements in soil health by providing additional carbon inputs, increasing the proportion of larger soil aggregates, and improving soil food web structure. We predicted the optimum cover crop mixture to maximize ecosystem function multifunctionality was 64% oat, 36% legume and 0% forage brassica. This study offers novel insight into the agronomic and environmental impacts of replacing fallow with cover crops in a subtropical dryland. It shows that integrating mixture of oat:legume cover crops can increase multifunctionality. Further research is required on the extent of ecosystem trade-offs between competing ecosystem functions. The predicted optimum cover crop mixture composition will likely vary when different ecosystem functions are considered or if long-term experiment data are used. Hence, the recommended optimum cover crop mixture must be interpreted with caution and cover crop selection should be based on practical recommendations according to target management goals. [Display omitted] • Integrating cover crops into a dryland crop rotation enhanced ecosystem functions compared to conventional fallow. • Cover crops enhanced 8 of the 14 measured ecosystem functions in a three-year rotation. • Oat:legume mixtures provided greater ecosystem multifunctionality than monocultures and Brassicaceae-associated mixtures. • The predicted optimum cover crop mixture that maximized ecosystem multifunctionality was 64% oat, and 36% legume. • Cover crop selection should be based on targeting specific ecosystem functions and local context. [ABSTRACT FROM AUTHOR]

Livestock production in China is increasing to meet demands for animal products, but is limited by feed resources. To explore additional forage options in north-west China, the biomass production and nutritive value of nine spring-sown annual crops (maize ( Zea mays) , sudan grass ( Sorghum sudanense ), small millet ( Setaria italica ), millet ( Panicum milliaceum ), soybean ( Glycine max ), common vetch ( Vicia sativa ), pea ( Pisum sativum ), oat ( Avena sativa ) and spring wheat ( Triticum aestivum )) were compared under rainfed conditions over two years. Water use efficiencies for biomass (WUE DM ) and nutritional yield indices, CP yield (WUE CP ) and relative feed value yield (WUE RFV ), were calculated. Maize produced the highest biomass yields of >10 t DM ha −1 and had the highest WUE DM . Biomass production was next highest in the other warm-season grasses such as sudan grass and millet species (6–9 t DM ha −1 ) and soybean (3–7 t DM ha −1 ), while spring wheat produced the most early biomass in spring ( P < 0.05). The legumes had higher crude protein concentration and produced equivalent or higher CP yields and WUE CP to the grasses (1.2–1.7 kg CP ha −1 mm −1 ). Maize and soybean had the highest WUE RFV of 26.4 kg ha −1 mm −1 and 19.4 kg ha −1 mm −1 , respectively. These integrated nutritional yield indices enabled comparisons of water productivity and optimal harvest timing across a range of forage types with differing nutritional characteristics and biomass production potential. [ABSTRACT FROM AUTHOR]

Understanding the quantity and timing of labour to fulfill the goals of different cropping systems or crop rotations is critical, but poorly quantified and understood in many agricultural systems, including the grain-growing regions of eastern Australia. Yet, labour supply and demands are important considerations for farmers and can significantly influence their agronomic management and decisions to adopt modified crop rotation systems. Here, we investigated the extent to which crop rotation systems, that differed in their intensity (i.e. the proportion of time when crops were growing), and diversity (i.e. the range of crops grown) influence labour requirements and labour productivity. We used the Agricultural Production Systems sIMulator (APSIM) to simulate a set of different crop rotations and combined the output with farmer survey data and expert knowledge derived from farm advisers to compute the labour inputs for key crop operations (i.e. sowing, spraying, harvesting). This information was used to calculate the labour required and the timing of this demand for each cropping system. We showed that as the cropping intensity increases the labour demand also increases, and vice versa. However, only small differences in labour demands were identified between systems with differing crop diversity (i.e. range of crops grown). Thus, when it comes to labour demands, crop diversity is less critical than cropping intensity. Labour demand was highly seasonal, with peaks around the intense operations of sowing and harvesting. These peak demands constrained the area that could be managed by a unit of labour, particularly as the cropping intensity increased. Further, this analysis highlights that the most profitable systems may not necessarily be the most efficient in terms of labour productivity (i.e. return per unit of labour). This analysis shows that when labour is limiting, labour demands and especially peak periods may contribute to a farmer's choice of cropping systems, adding to other critical factors like risk aversion and profit maximisation. The analysis contributes to the literature on the role of labour in the context of influencing the implementation and adoption of what are seemingly more productive or profitable farming systems. In particular, the results demonstrate how labour as a critical farm resource (i.e. its quantity, seasonality and timing, and productivity) can influence the design of crop rotations. [Display omitted] • Many cropping systems in Australia are being modified by altering their intensities and crop diversity, but their labour demands are unknown. • Crop rotations with distinct intensity and diversity are simulated in APSIM to estimate their labour demands, seasonality, and economic returns. • Altering cropping intensity had stronger influence on labour demands and returns than changing the crop diversity in the rotation. • Labour demands between rotations is not substantial to influence a farmers decision on adopting alternative or modified cropping sequences. • Findings contribute to the growing discussion on the role of labour for the design and potential feasibility of innovative cropping systems. [ABSTRACT FROM AUTHOR]

Forage brassicas have historically been used in high rainfall/irrigated temperate livestock systems, but there is increasing interest in diverse forage brassicas in drier mixed crop-livestock farming systems. Computer-based modelling is an important decision support tool used in agriculture to explore the adaptability of crops to different climates and agronomic management practices, but existing modelling tools for forage brassicas are limited to temperate environments. We parameterised the APSIM (Agricultural Production Systems Simulator) model for four forage brassica genotypes, including three diverse forage rape cultivars and a raphanobrassica. The model was calibrated using two experiments with repeated measures of biomass components, nutritive value, and leaf and canopy development. We then tested the model extensively using data from a diverse set of environments within Australian and New Zealand (23 sites across four agro-climatic zones). Model predictions of biomass were good for all the genotypes (NSE > 0.60, Nash-Sutcliffe efficiency; RMSE ~1.5 t DM/ha, root mean square error). Predictions of metabolisable energy yield were satisfactory for all genotypes (NSE 0.43–0.73; RMSE ~17.8 GJ ME/ha) but forage dry matter digestibility (DMD) were poorly predicted due to the small variation in observed data. Our robust and widely tested model can be confidently used to predict forage productivity of common and new forage brassicas across a wide range of production environments and agronomic management practices. This model will enable future work to develop a better understanding of the potential value of these important forage crops for livestock production systems. • A forage brassica model, including three diverse forage rape cultivars and a raphanobrassica were parameterised in APSIM. • Forage brassica productivity during vegetative growth can be modelled in different environments and agronomic practices. • These new capabilities enable the value of forage brassicas to farming systems to be explored in different environments. [ABSTRACT FROM AUTHOR]

Substantial initiatives are occurring in developing countries to integrate forage crops into crop-livestock systems to improve farmer livelihoods and reduce soil erosion. In particular, government authorities in western China focus on improving farmer livestock profits through greater forage crop production. We examined the whole-farm profit, downside risk, labour-use efficiency and feed balance effects of forage crop intensification on two simulated crop-livestock farm types in western China. Our methodology combined crop and livestock simulation modelling with whole-farm stochastic budgeting to capture both price and climate variability. We modelled the whole-farm effects of (1) introducing either forage vetch (Vicia sativa), forage oats (Avena sativa), or grain soybean (Glycine max) into current wheat (Triticum aestivum)-maize (Zea mays) systems and (2) replacing maize in current wheat-maize systems with either forage wheat, forage maize, or forage soybean. System intensification through incorporating a forage crop into current grain-cropping systems can increase average simulated profits without increasing downside risk on the simulated farms. As opposed to adding a forage crop into current grain-cropping systems, replacing a grain crop with a forage crop in current grain-cropping systems had a negative effect on profits, downside risk, and labour-use efficiency. Trade-offs existed between labour-use efficiency and profit as forage intensification increased labour demands. These effects were context specific, with greater positive profit effects of forage intensification for the higher-rainfall farm type. Overall, forage intensification in these systems benefited the households, but adoption will depend on household preferences and local agro-ecological and market factors. We demonstrated the importance of exploring proposed intensification options across different locations to capture impacts across diverse contexts. Providing these context-specific insights and exploring trade-offs within systems can help better understand livelihood improvement pathways. In locations with strong competing uses for labour, developing labour-saving practices appears critical. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mixing crops and livestock helps Australian farmers manage climate, price and soil variability. [•] Recent crop–livestock innovations can improve farm productivity, sustainability and reduce risk. [•] Potential for grazing dual-purpose cereal and canola crops or sacrificially grazing crops is unrealised. [•] Perennial pasture phases in grain crop rotations can provide multiple farm benefits. [•] Systems growing mixtures of crops and pastures and to utilise novel pasture species are evolving. [ABSTRACT FROM AUTHOR]

• Tropical forage legumes were grown in rotation or relays with maize and rice. • Subsequent maize yields increased by up to 80 % if legumes were retained as mulch. • Maize yield increased less (15−35% higher) after legume forage was harvested. • Forage legumes grown in rotation with rice increased subsequent yields by 40–70 %. • Clitoria ternatea proved the most beneficial forage legume for diverse systems. In temperate systems, it is well known that forage legumes can improve both nitrogen (N) supply and yields of subsequent cereal crops. While this is assumed to be true in tropical systems, it is less well tested, particularly in smallholder settings where forage is often cut and removed from the field. This paper confirms the potential of short phases of tropical forage legumes to provide N to subsequent crops in seasonally dry tropical farming systems. Across five experiments, maize and rice grain yields increased by up to 80 % after 4−8 month rotations of forage legumes, but the benefits were smaller when legume growth was reduced, biomass was removed for forage, or the yield potential of cereal crops was lower. We found that the additional N cycling from legumes can last for at least 2 years, although the benefit diminishes with time. When all legume material was retained as mulch, the estimated additional N provided to subsequent no-till maize crops was the equivalent of 9−15 kg urea-N per tonne of above-ground legume biomass produced but fell to 1.5−3 kg urea-N/t if forage was removed. After shoot removal, more legume N cycled to a subsequent rice crop (equivalent of 11–13 kg urea-N/t of legume biomass) than to a no-till maize crop, presumably because more below-ground material mineralised. Of the legumes tested, Clitoria ternatea grew best across a variety of environments and use patterns and provided the largest yield benefits to subsequent crops. This research demonstrates the potential to integrate short phases of tropical herbaceous forage legumes into smallholder crop-livestock systems in the seasonally dry tropics, and, in doing so, improve or maintain staple grain crop production and household food self-sufficiency. [ABSTRACT FROM AUTHOR]

Abstract: Australia has a long history of mixed farming. This paper examines the integration of Australian cropping and livestock production from three perspectives: as a factor in land use change, a consequence of individual management practices and a means of meeting farmers’ multiple objectives. Since about 1995, the proportion of cropped land has increased on Australian cropping farms while livestock numbers have decreased. Land use in the north-eastern, central and south-western regions of the cropping zone have diverged. Despite these changes, mixed farms still dominate Australia’s broadacre farming regions. Previous accounts of the dimensions in which farming enterprises are integrated can be simplified for Australian broadacre agriculture. For most purposes it is sufficient to consider a nested set of four integration options: “specialization” (not integrated organizationally), “separation” (integrated organizationally only), “rotation” (integrated organizationally and spatially, but not temporally) and “synchronization” (integrated in all three dimensions). We illustrate these integration options with a short survey of agronomic practices that affect crop–livestock integration. We review the farmer objectives that enterprise integration can meet and the constraints that limit it, seeking to balance social, economic and agronomic factors. We use a dynamic simulation model to make a first quantification of the economic risk reduction provided by enterprise diversification. Constraints imposed by limited labour, capital, and management attention cannot be overlooked; this is especially relevant in Australia where labour is increasingly in short supply. We characterize our surveyed set of agronomic practices with respect to the farmer objectives they affect. We find that farmers generally have the option of meeting a particular objective through different practices that affect different dimensions of integration. Practices that result in closer integration in time and space generally require greater management attention; practices that do not integrate in space typically require an increase in external inputs. History suggests that current commodity price ratios may be sufficient to slow or reverse the overall land use trend away from livestock production. In the longer term, forecast increases in worldwide demand for meat, energy costs and soil resource constraints will all encourage Australian cropping farmers to maintain mixed systems; however reduced availability of labour relative to capital will push land use toward specialized systems. Valuing the benefits and costs associated with differing degrees of enterprise integration is a major research challenge that will require insightful application of both biophysical and economic models. [Copyright &y& Elsevier]

Abstract: The development of perennial wheat could have a number of advantages for improving the sustainability of Australian dryland agricultural systems. The profitability that might be expected from perennial wheat of different types was investigated using MIDAS (Model of an Integrated Dryland Agricultural System), a bioeconomic model of a mixed crop/livestock farming system. Although perennial wheat may produce a lower grain yield and quality than annual wheat, it is expected inputs of fertiliser, herbicide and sowing costs will be lower. Perennial wheat used solely for grain production was not selected as part of an optimal farm plan under the standard assumptions. In contrast, dual-purpose perennial wheat that produces grain and additional forage during summer and autumn than annual wheat can increase farm profitability substantially (AU$20/ha over the whole farm) and 20% of farm area was selected on the optimal farm plan under standard assumptions. Forage from perennial wheat replaced stubble over summer and grain supplement at the break of season and increased farm stock numbers. The additional value added by grazing also reduced the relative yield required for perennial wheat to be profitable. This analysis suggests perennial wheat used for the dual purposes of grain and forage production could be developed as a profitable option for mixed crop/livestock producers. [Copyright &y& Elsevier]

Maintaining the productive capacity of the agricultural soils of Australia's broadacre cropping zone requires careful management, given a highly variable climate and soils that are susceptible to degradation. Mixed crop-livestock farming systems are the predominant land use across these regions and managers must operate farms for long-term sustainability as well as shorter-term profitability. Achieving profitable and sustainable businesses has required ongoing innovation and productivity gains, of which the integration of crop and livestock enterprises has been an important part. Production-soil erosion trade-offs associated with enterprise integration is critical information that has not been investigated to date at a whole-farm level. The objective of this study was to systematically evaluate management options developed in Grain and Graze (an integrated program of research, development and extension targeting mixed farms) to identify farm systems responses to soil erosion risks across seven regions spanning the mixed-farming area of Australia. To evaluate production-soil erosion trade-offs, we linked the APSIM soil water, soil nutrient cycling, annual crop and surface residue simulation models to the GRAZPLAN pasture and ruminant simulation models, using the AusFarm modelling software. Our results demonstrate that the management options tested in Grain and Graze support the principles of conservation agriculture and inform the sustainable intensification of mixed farming systems. Across the regions considered we found that: (1) Increasing pasture legume content and soil fertility can consistently benefit farm production and environmental indicators, (2) management interventions that target direct management of ground cover have the greatest potential to reduce soil erosion rates, (3) management during critical periods of naturally high soil erodibility and wind/water erosivity can substantially increase or decrease erosion risk; the timing of management interventions is therefore critical, and (4) grazing management to balance use of crop residues and pasture biomass is required to avoid developing hot spots of erosion and soil degradation. [ABSTRACT FROM AUTHOR]

Temporal variability in the availability of forage reduces the production and economic performance of livestock systems. The marginal value of feed (MVF, the possible gross economic benefit of additional feed on offer during an annual cycle), was assessed under the expected variability of climate and prices in a cow-calf operation from the Flooding Pampas, Argentina. Herbage mass accumulation (HMA) was simulated on a daily basis over 20 different years with DairyMod, grouped by month and season and where the HMA was equal or below 50% of its long-term average, it was tagged as “Dry”. Typical monthly pasture growth rates were synthetically depicted for average years (Average), or with dry autumn (D-Au), winter (D-Wi), spring (D-Sp) or summer (D-Su) conditions. These pasture growth curves were incorporated into whole-farm scenarios which were modelled with SIMUGAN, a bio-economic whole-farm model. Farm scenarios were baseline (unchanged HMA) or with additional 10% of the annual HMA. This additional feed was either evenly distributed across each month of the year (all year), or the full amount provided in one of the four seasons. These scenarios were repeated in a factorial design across a range of stocking rates (SR; 0.9–1.3 cows/ha) on an average year or years including one dry season (D-Au, D-Wi, D-Sp orD-Su). SIMUGAN results were fed to an ad-hoc built model to calculate production and market risk profiles. In years with average HMA, MVF were always below 0.05 US$/kg DM but the presence of a dry season caused significantly higher MVF. Years with dry autumn presented the highest economic responses when the extra feed was fed during autumn or winter. MVF analyses showed a positive impact of additional forage only above 1.1 head/ha and this increased with SR, whereas MVF at the low SR were mostly negative due to extra hay making costs. At 1.1 and 1.2 head/ha, allocating additional feed in autumn produced a higher return (0.04 and 0.08 US$/kg DM) than feed provided at other times of the year (averaging 0.02 and 0.05 US$/kg DM). Otherwise, at 1.3 SR extra feed in winter always had the highest MVF (up to 0.19 US$/kg DM). Bio-physical variables of livestock demand and seasonality of pasture growth were the main drivers of MVF variability. Overall, the framework developed by integrating forage, livestock and economic models “in a series” effectively identified the economic feasibility of changes to the farm feed-base under different climatic and livestock management conditions. [ABSTRACT FROM AUTHOR]

Increasing demand for livestock products is driving development of livestock systems worldwide. That requires improved and new forage production options. The Loess Plateau region in central-northern China is an important area for livestock production, as it supports11% and 19% of the country’s cattle and sheep, respectively (China statistical yearbook 2014). The rain-fed semi-arid environment of the Loess Plateau means that maximizing the water-use-efficiency (WUE) of forage production is vital to guarantee enough fodder supply the livestock demand. A three-year field experiment in north-west Loess Plateau compared forage production, water use and water-use-efficiency as well as crude protein (CP) content of forage maize, Sudan grass, foxtail millet and Japanese millet sown at three sowing dates according to the opening rain during 2011–2013. On average, forage maize produced the highest biomass (12.1 t ha −1 ) and had the highest WUE (43.4 kg DM ha −1 mm −1 ). This was followed by Sudan grass (7.8 t ha −1 ; 26.5 kg DM ha −1 mm −1 ), Japanese millet (6.7 t ha −1 ; 26.2 kg DM ha −1 mm −1 ) and foxtail millet (6.7 t ha −1 ; 24.6 kg DM ha −1 mm −1 ). Optimizing sowing date played an important role in maximizing forage production and WUE of all tested forages. Compared to the earliest sowing date, a delay of two weeks reduced forage production by 17% in maize, 35% in foxtail millet, and 16% in Japanese millet. A delay of four to six weeks reduced biomass yield by 58% in maize, 57% in foxtail millet, and 56% in Japanese millet. Late sowing also greatly reduced WUE of forage maize and foxtail millet by 33% and 42%, respectively, when compared to early sowing. The middle sowing date maximized forage production and WUE of Sudan grass in two of the three growing seasons, which was 20% and 38% higher than the early and late sowing, respectively. Late sowing in all forages reduced crop water use by 42–57 mm compared to the early sowing. Among four test crops, CP of Sudan grass (7.9%) and forage maize (7.7%) was higher than foxtail millet (6.8%) and Japanese millet (6.7%). Compared with early sowing, CP f in late sowing significantly increased in Sudan grass and decreased in Japanese millet, in contrast, no evident sowing date effect was found in forage maize and foxtail millet. This study showed that all four warm-season annual grasses had high forage production potential, forage maize was the most reliable and efficient option. Forage maize and the millets could easily be integrated into existing cropping systems and provide opportunities as both grain and forage-producing crop to provide added flexibility for farmers. [ABSTRACT FROM AUTHOR]

Abstract: Simulation models can help to identify the whole-farm economic and biophysical impacts of smallholder farmers altering their farming systems. Incorporating long-term climate-induced variability in crop and livestock production enables the implications for agricultural household income and risk to be explored over a range of seasonal conditions. In this study, a simulation model is used to answer the following question: can reducing the area used for grain production by allocating more land to lucerne (Medicago sativa) and increasing livestock numbers improve total net farm income, reduce income variability and maintain grain self-sufficiency for farmers in the Qingyang Prefecture of Gansu Province, China? This was examined for three representative farm types found in the region: a low land-labour ratio farm household, a subsistence-oriented farm household, and a livestock-focused farm household. The Integrated Analysis Tool (IAT), a simulation model of a household farming system, was used to combine crop and forage production simulations, a livestock production model and a household socio-economic model to explore the impact of changes to farming systems over a 40year simulation period. Data from 90 surveyed households were used to define the structure of the three farm household types and to calibrate the IAT model specifically for Qingyang Prefecture. Additional livestock increased total household net incomes, increased net livestock incomes and reduced net crop incomes for the subsistence-oriented and livestock-focused farm households. For these households, the greater commitment to livestock also reduced grain self-sufficiency due to increased frequency of purchasing grain for home-consumption. Nevertheless, additional livestock reduced income variability for these households whilst improving total net income. The methodology used is useful for understanding changes in farming systems as it focuses on the feasibility and profitability of alternative enterprise mixes and incorporates climate variability. The results support current debates on targeting livestock policies towards smallholders as subsistence-oriented farm households appear to be the largest beneficiaries from livestock interventions. The analysis demonstrates that tradeoffs between net income and grain self-sufficiency are important for households, especially when they are moving from subsistence-based to market-based production. [Copyright &y& Elsevier]

Highlights • Delaying sowing date shortened time of emergence of maize, Sudan grass, foxtail millet and Japanese millet. • Variation of leaf area per plant of three forage crops was caused by leaf area elongation rate (LAER). • The relationship between final leaf number on main culm and climatic conditions varied with forage species. • Maize, Sudan grass, foxtail millet and Japanese millet displayed a strong phenotypic plasticity. Abstract Annual forage crops attract more attention to researchers for it can be used as both forage in animal production and ethanol production in industry. Sowing date are critical to increase crop yield potential in semi-arid environments. Successful establishment and canopy develop are two key aspects ensuring the final yield of forage crop. Therefore, emergence time, leaf appearance and solar radiation interception by the canopy were measured with four annual forage grasses [maize (Zea mays), Sudan grass (Sorghum sudanense Stapf., S), foxtail millet (Setaria italic) and Japanese millet (Echinochloa crus-galli var. frumentacacea)] during the period of 2011–2013 in the western Loess Plateau of China. The results showed that a delay of sowing date could decrease the time for crop emergence. In addition, a decrease in the final leaf number (FLN) and the individual leaf area (ILA) (maize, foxtail millet and Japanese millet) from delayed sowing resulted in less light interception (RI). The variation FLN was closely related to day length (DL) and initial soil water and rainfall at flowering (W s +R f) for maize and foxtail millet, thermal time (TT), DL and W s +R f for Sudan grass and Japanese millet. Changes in leaf area per plant (LA single) in Sudan grass, foxtail millet and Japanese millet were caused by leaf area elongation rate (LAER). Sowing date did not affect leaf appearance rate (LAR) in Japanese millet while decreased in Sudan grass and increased in foxtail millet when the sowing date was delayed, mainly due to changes in DL, TT and W s +R f. Variations in individual leaf area (ILA) and LAER indicated the strong plasticity of the four crop species. Therefore, the results of this study improved the understanding of the relationship between sowing date and canopy development and provide important information in crop management and breeding to increase the crop yield. [ABSTRACT FROM AUTHOR]

Agricultural systems models worldwide are increasingly being used to explore options and solutions for the food security, climate change adaptation and mitigation and carbon trading problem domains. APSIM (Agricultural Production Systems sIMulator) is one such model that continues to be applied and adapted to this challenging research agenda. From its inception twenty years ago, APSIM has evolved into a framework containing many of the key models required to explore changes in agricultural landscapes with capability ranging from simulation of gene expression through to multi-field farms and beyond. Keating et al. (2003) described many of the fundamental attributes of APSIM in detail. Much has changed in the last decade, and the APSIM community has been exploring novel scientific domains and utilising software developments in social media, web and mobile applications to provide simulation tools adapted to new demands. This paper updates the earlier work by Keating et al. (2003) and chronicles the changing external challenges and opportunities being placed on APSIM during the last decade. It also explores and discusses how APSIM has been evolving to a “next generation” framework with improved features and capabilities that allow its use in many diverse topics. [ABSTRACT FROM AUTHOR]

• Effect of sowing date on biomass partition varied with forage crop species. • Aboveground biomass at flowering was dependent on rainfall and solar radiation. • Aboveground biomass at maturity more reliant on temperature and rainfall. • Allometric approach should be used in the analysis of allocation pattern. Biomass production and partitioning are important for crop production and is influenced by environmental conditions. Sowing date can profoundly influence biomass production and portioning in crop plants depending upon the local climatic conditions. However, the accumulation of biomass in different plant components in annual forages in response to changes in sowing date has not been quantified, especially for semiarid farming systems. A field experiment was conducted during 2011–2013 to investigate how sowing date (early, mid, late) influences biomass partitioning and the interrelationships with environments in four warm-season annual crops in the Loess Plateau of China. The aboveground biomass of all four crops was more reliant on rainfall and solar radiation at flowering and temperature and rainfall at maturity. Solar radiation, rainfall, and temperature had a combined effect on belowground biomass (0–0.3 m), depending on the forage crop. Reductions in biomass in the late-sown treatment were mostly attributed to plant size; the 'allometry' among plant components did not change. The changes of shoot: root and leaf: stem ratios were related to the relationship between biomass accumulation and rainfall, temperature and intercepted radiation. It is evident that dry matter allocation patterns in crops must be analyzed using a dynamic approach (allometry) and relate with environmental conditions, rather than a static approach using ratios. The results from this study provide references for crop management in forage production and breeding in semiarid areas. [ABSTRACT FROM AUTHOR]