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Synthesis and analysis of past cropping research can provide valuable information to direct future decisions around crop management. Systematic reviews and meta-analyses are considered gold standards in the synthesis and analysis of scientific research because they distil large amounts of information about complex issues, provide a summary of knowledge to date, and identify knowledge gaps. However, several issues concerning the methodologies employed to conduct systematic reviews have been identified; among them is the risk of publication bias when a review relies too heavily on ‘white’ literature from published academic sources and in so doing fails identify relevant ‘grey’ literature. Grey literature is inherently difficult to identify and collect, but forms a large portion of information available in many fields including agricultural-based research within Australia. The Online Farm Trials (OFT) database is a digital database of crop research field trial data from across Australia that has the potential for use as a discipline-specific source of grey literature to inform systematic reviews and meta-analyses. Using a case study approach to investigate the amount of information available on time of sowing (sowing date) on crop yield across Australia, we demonstrate that the OFT database provides easy access to transparent and reproducible search results similar to other commonly used academic databases.

The fragile balance in the world’s carbon equilibrium through the discovery of cheap carbon-based fuels in the nineteenth century has led to mass industrialisation and an explosion in the world human population, including that of Pakistan. Farmers worldwide will need to adapt their production systems to accommodate global warming and increased climate extremes resulting from these man-made environmental changes. The focus will need to be on smallholder farmers who generate 53% of the world’s food but who are least equipped to accommodate climate change. The most major limitation will be fresh water supply, no more exemplified than in Pakistan as Himalayan snowfall decreases and peak snow melt comes earlier in spring, limiting irrigation water for summer C4 crops such as corn, millet, sorghum and sugarcane. These are destined to replace the traditional C3 crops of wheat and rice, which will not be as suited to climate change conditions resulting from a projected mean 2°C rise in ambient temperature. Smallholder farmers will need to access superior-quality seed for crop cultivars for both human food and animal forage bred to withstand climatic change. Quantitative genetic selection programs for tropically adapted livestock must be implemented with a major focus on Pakistan’s Nili Ravi and Kundhi buffalo, together with Sahiwal cattle servicing the milk consumption needs of Pakistan’s burgeoning population of 211 million. The quality of forage available for livestock emanating largely from crop residues needs to be improved to meet the country’s greenhouse-gas production targets in line with international expectation. The challenge remains for governments to sustain marketing chains that allow them to be profitable when operating in an increasingly hostile environment. The conservation of soil fertility through increased carbon sequestration will be an important imperative. It is likely that females will play a more important role in directing adaptation in these communities. Successful adjustment will be dependent on effective extension programs working with all sectors of the community including males, females and children from all walks of life in both rural and urban environments. Failure to do so will lead to rapid increases in climate refugee numbers, which the world can ill-afford.

Dual-purpose cropping (sowing crops with the intention of both grazing them during vegetative growth and harvesting grain thereafter) has become a widespread farming practice in southern Australia. This synopsis paper integrates research from a multi-institutional research project conducted at three nodes located near Hamilton (south-western Victoria), Wagga Wagga (southern NSW) and Canberra (ACT), and sets out 11 principles for the effective utilisation of dual-purpose crops in meat production systems to increase profit and manage risk. Dual-purpose crops can be used to overcome feed quality gaps in late summer–autumn or feed quantity gaps in late autumn/winter. They provide large quantities of high-quality forages for grazing in summer, autumn and winter and can provide a substantial contribution to the annual number of grazing days on a farm. Utilisation of the high-quality dry matter provided by dual-purpose crops is most effective when directed at young growing stock for sale or future reproduction rather than reproducing adult ewes. For example, sale weight of yearlings per ewe was increased by 16% in systems at the Canberra node when dual-purpose crops were prioritised for grazing by weaners. Wool production was also increased in systems that included grazing of dual-purpose crops. Grazing crops in winter does not necessarily reduce supplementary feeding costs for winter or spring lambing. Modelling suggests that inclusion of dual-purpose crops does not substantially change the optimum time of lambing for sheep meat systems. Financial analysis of the experimental data from the Canberra node showed that although cash expenses per hectare were increased in the crop-grazing systems, the overall profitability of those systems over the life of the experiment was greater by AU$207/ha.year than that of the pasture-only system. Factors driving improved profitability included income from grain, higher income from meat and wool, and lower supplementary feeding costs. However, increasing the area sown to crop from 10% to 30% of the farm area in this Southern Tablelands system appeared to increase risk. In south-western Victoria, spring-sown canola carried risk similar to or less than other options assessed to achieve ewe-lamb mating weight. It is likely that at least part of the reduction in risk occurs through the diversification in income from the canola produced as part of the system. It was concluded that the grazing of cereal and canola crops for livestock production can be profitable and assist in managing risk.

Context The Acland Land System overlying the Walloon sandstone coal deposits in southern Queensland is generally marginal for cropping but well suited to grazing, and thus cultivated land is commonly returned to pasture. Rehabilitation of these lands after open-cut coal mining seeks to be safe, stable and self-sustaining to satisfy requirements for ecologically sustainable development. Aims The present paper evaluates the sustainability and economic viability of beef production on (a) lands retired from cultivation and then rehabilitated with sown pastures after open-cut coal mining at the New Acland mine site, and (b) similar nearby pasture lands that were not mined but were also retired from cultivation. Methods The GRASP grazing systems model was modified and calibrated with short-term (5-year) grazing trial data (soil, pasture and cattle observations), and then used with long-term (60-year) weather data to estimate effects of land type, pasture rundown, climate and grazing pressure on productivity and economic returns. The productivity of three rehabilitated sites and 15 unmined sites were evaluated, including pastures on six commercial properties. Key results Estimates of long-term mean annual growth of pastures on unmined lands retired from cultivation on three land types (Mountain Coolibah, Brigalow Uplands and Poplar Box) were 3398, 2817 and 2325 kg/ha respectively. Pasture growth was greater on rehabilitated lands; 3736 kg/ha on the site most typical of rehabilitated lands and a mean of 4959 kg/ha across three sites. Seasonal conditions had large effects on cattle liveweight gain (133–213 kg/head per year during the trial); however, pasture growth was the main driver of beef production and economic returns per hectare. In GRASP, potential nitrogen uptake was used to influence key pasture growth processes and accounted for 64% of variation in observed annual growth. The short-term lift and subsequent rundown in productivity typically associated with sown pastures was estimated to have increased mean annual pasture and cattle productivity during the 2014–2018 trial period by up to 17% and 25% respectively. Estimates of long-term mean annual beef production and economic returns for the unmined lands were less than estimated for rehabilitated lands and were 139 kg/head.year (45 kg/ha.year) and AU$154/adult equivalent. Conclusions Rehabilitated lands were found to be sustainable for beef production at grazing pressures up to 30% utilisation of annual pasture growth, and comparable with grazing systems on native and sown pastures in good condition. Pastures on unmined lands retired from cultivation had reduced productivity. Implications Overgrazing is a significant and on-going residual risk to sustainable production. Grazing regimes need to continually adjust for changes in novel landscapes, pasture condition and climate. The methods used in the present study could be applied more generally.

Context Increasing demand for livestock products in developing countries provides opportunities for smallholder farmers to increase and diversify their income through increased livestock production. However, livestock production in these systems is often limited by inadequate animal nutrition, and farmers need ways to increase the availability and quality of livestock feed without compromising yields of food crops or increasing the area of land planted to forages. Aim Using eastern Indonesia as a case study, we explore the potential for herbaceous legumes, integrated into existing mixed crop–livestock systems, to address specific production issues in smallholder beef systems. Methods Through a series of in-village feeding demonstrations, we tested three opportunities to increase livestock production through the use of herbaceous legumes: (i) increasing reproduction rates of cows by maintaining their liveweight (LW) and body condition score during the dry season; (ii) increasing the survival and LW gain of unweaned calves; and (iii) increasing LW gain of growing bulls. Key results Small amounts of legume (~10 g DM/kg LW) were enough to maintain LW of cows grazing poor-quality grasses and crop residues during the dry season. At higher levels of inclusion in the diet (~20 g DM/kg LW), feeding legumes increased the LW gain of growing cattle and survival of unweaned calves, providing benefits similar to a purchased concentrate, but at lower cost. Conclusions Our results demonstrate how strategic use of herbaceous legumes can increase beef production from low-input systems by maintaining LW of cows, and increasing survival of unweaned calves and LW gain of growing bulls. Implications Integration of herbaceous legumes into existing cropping systems removes many of the barriers to supplementary feeding. Improved livestock nutrition does not need to be based on purchased concentrates or increases in land used for forage production. The results are applicable to many other mixed crop–livestock systems throughout Southeast Asia.

Increases in temperature, along with possible decreases in rainfall, will influence the production of forage on Australian dairy farms. A biophysical simulation study was undertaken to compare the performance of perennial pastures and annual forage cropping systems under a historical scenario and two possible future climate scenarios for three key dairy locations of south-eastern Australia. Pastures and forage-cropping systems were simulated with the biophysical models DairyMod and APSIM, respectively, for a location with a heavy reliance on irrigation (Dookie, Victoria), a location with a partial reliance on irrigation (Elliott, Tasmania), and a dryland location (Terang, Victoria). The historical climate scenario (baseline scenario) had no augmentation to climate data and an atmospheric CO2 concentration of 380 ppm, whereas the two future climate scenarios had either a 1°C increase in temperatures (with an atmospheric CO2 concentration of 435 ppm) and a concurrent 10% decrease in rainfall, or a 2°C increase in temperatures (with an atmospheric CO2 concentration of 535 ppm) and a concurrent 20% decrease in rainfall. At Dookie, mean annual dry matter yields of the forage-cropping options and the pasture systems increased under both future climate scenarios but more irrigation was required. At Terang, the yield of forage-cropping systems increased whereas the yield of the pasture systems decreased under the future climate scenarios. At Elliott, yields of irrigated pastures and cropping systems increased but there was minimal or a negative impact on yields of dryland pastures and cropping systems under the future climate scenarios. At all three locations, forage production increased in the colder months of the year with a decrease in production during the warmer months. This study indicates that double-cropping and irrigated-pasture systems at all three locations appear resilient to projected changes in climate; however, for irrigated systems this assumes a reliable supply of irrigation water. The systems implications of how a shift in the seasonality of forage supply within these options impacts on the farm system as a whole warrants further investigation.

Meeting future food needs without compromising environmental integrity is a central challenge for agriculture globally but especially for the Asia Pacific region – where 60% of the global population, including some of the world’s poorest, live on only 30% of the land mass. To guarantee the food security of this and other regions, growers worldwide are rapidly adopting genetically modified (GM) crops as the forerunner to protect against many biotic and abiotic stresses. Asia Pacific countries play an important role in this, with India, China and Pakistan appearing in the top 10 countries with acreage of GM crops, primarily devoted to Bt cotton. Genetically Modified Crops in Asia Pacific discusses the progress of GM crop adoption across the Asia Pacific region over the past two decades, including research, development, adoption and sustainability, as well as the cultivation of insect resistant Bt brinjal, drought-tolerant sugarcane, late blight resistant potato and biotech rice more specific to this region. Regulatory efforts of the Asia Pacific member nations to ensure the safety of GM crops to both humans and the environment are also outlined to provide impetus in other countries initiating biotech crops. The authors also probe into some aspects of gene editing and nanobiotechnology to expand the scope into next generation GM crops, including the potential to grow crops in acidic soil, reduce methane production, remove poisonous elements from plants and improve overall nutritional quality. Genetically Modified Crops in Asia Pacific provides a comprehensive reference not only for academics, researchers and private sectors in crop systems but also policy makers in the Asia Pacific region. Beyond this region, readers will benefit from understanding how GM crops have been integrated into many different countries and, in particular, the effects of the take-up of GM cropping systems by farmers with different socioeconomic backgrounds.

Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha–1 year–1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha–1 year–1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.

Current data are needed to manage our soil resources but there are few recent purpose-built surveys of soil fertility, a critical asset for natural resources management. Instead, data collected for other purposes are re-used as has been the case in our area of interest here: managing the threat of soil erosion on farm land in East Gippsland. The dynamic nature of soil fertility challenges this approach, so we conducted a new survey using 234 paddocks selected at random. These new data were compared to re-purposed legacy data. Plant tissue samples from a selected subset were used to assess micronutrients. Separately, 27 paddocks that had been sampled during 1975–89 were re-tested to examine temporal changes. We concluded that many paddocks are now strongly or very strongly acidic and deficient in molybdenum (Mo) and boron (B). More specifically, those under dairying, cropping and horticulture are likely to have adequate phosphorus (P) while those grazed for meat and wool are likely to be deficient in P. We concluded that grazing enterprises need to either re-adopt soil testing and fertiliser treatment or adopt management practices suitable for acid soils deficient in P, Mo and B, if their paddocks are to support sustainable productive agriculture. Data from the re-tested paddocks suggest that, in general, many were once less acidic, highlighting the difficulties in using legacy data. Also, contrasts in soil pH and available P between paddocks under different management regimes, highlighted the difficulties in using re-purposed data. We concluded that a statistically designed survey is a preferable basis for natural resource management.

Sustaining diverse, yet productive crop sequences that integrate break crops such as canola (Brassica napus L.) remains a critical challenge for farming systems in low-rainfall cropping environments. Recent advances in canola productivity through early sowing, understanding of critical stress periods, hybrid cultivars and improved nitrogen (N) fertilisation offer promise under many conditions but require careful adaptation for risky, low-rainfall environments. A series of eight experiments was implemented over four growing seasons (2015–18) in the low-rainfall environments of southern Australia to test combinations of sowing date, cultivar selection and N-management strategies. Simulation modelling extended the field experiment results, enabling a simple, whole-farm profit–risk analysis across growing season deciles. The aim was to identify combinations of practices where the potential production and risk were understood, thereby assisting management decisions in low-rainfall cropping systems. Earlier sowing (April) was generally beneficial but only where seasonal conditions led to successful establishment, meaning that the best fit for canola in low-rainfall environments is as an opportunity crop. A hybrid cultivar (triazine tolerant) did not provide a yield advantage in an early experiment, but productivity increases were measured with a modern hybrid cultivar (Clearfield) in a later experiment. Profit-risk analysis suggested that a yield advantage of >20% over open-pollinated cultivars needs to be sustained across the full range of season deciles to generate economic advantage. Although there was relative insensitivity to the timing of N application, an adequate dose of N, either through fertiliser or legume crops, was critical to improve canola productivity. We conclude that opportunities exist to make significant gains in yield (by up to 110% compared with current standard practice) and profit–risk outcomes (~30% increased gross margins across all season types) for canola in low-rainfall environments by using a package of agronomic management decisions that includes early sowing on genuine establishment opportunities, hybrids that offer sustained yield benefits, and matching N dose from both fertiliser and legume crops to yield potential of the soil type and seasonal outlook.

The shift in Indian Ocean sea surface temperatures in 1976 led to a change in rainfall for the broad-scale winter annual grain cropping and pasture region in the south-west of Western Australia (the WA wheatbelt). Agriculture in the eastern part the WA wheatbelt was particularly sensitive to the change in rainfall because it is a marginal area for agronomic production, with low rainfall before changes in sea surface temperature. A second shift in sea surface temperature occurred in 2000, but there has been no analysis of the resulting impact on rainfall in the eastern WA wheatbelt. An analysis of rainfall pre- and post-2000 was performed for sites in the eastern WA wheatbelt in three groups: 19 sites in the west, 56 central, and 10 east. The analysis found a decline in growing-season rainfall (i.e. April–October), especially during May–July, post-2000. Rainfall declines of 49.9 mm (west group), 39.1 mm (central group) and 28.0 mm (east group) represented respective losses of 20.1%, 17.4% and 14.2% of growing-season rainfall. Increases in out-of-season rainfall in the respective groups of 31.0, 33.6, and 50.7 mm (57.8%, 60.8% and 87.6%) meant that annual rainfall changes were smaller than growing-season losses. The west and central groups lost 17.5 and 6.16 mm annual rainfall, whereas the east group gained 15.6 mm. Analysis of wheat yield indicated reductions of 13.5% (west) and 9.90% (central) in the eastern WA wheatbelt; the small group of east sites had a potential yield gain of 8.9% arising from the increased out-of-season rainfall. Further, increased out-of-season rainfall will exacerbate weed and disease growth over the summer fallow.

Late-maturity alpha-amylase (LMA) is a key concern for Australia’s wheat industry because affected grain may not meet receival standards or market specifications, resulting in significant economic losses for producers and industry. The risk of LMA incidence across Australia’s wheatbelt is not well understood; therefore, a predictive model was developed to help to characterise likely LMA incidence. Preliminary development work is presented here based on diagnostic simulations for estimating the likelihood of experiencing environmental conditions similar to a potential triggering criterion currently used to phenotype wheat lines in a semi-controlled environment. Simulation inputs included crop phenology and long-term weather data (1901–2016) for >1750 stations across Australia’s wheatbelt. Frequency estimates for the likelihood of target conditions on a yearly basis were derived from scenarios using either: (i) weather-driven sowing dates each year and three reference maturity types, mimicking traditional cropping practices; or (ii) monthly fixed sowing dates for each year. Putative-risk ‘footprint’ maps were then generated at regional shire scale to highlight regions with a low (66%) likelihood of experiencing temperatures similar to a cool-shock regime occurring in the field. Results suggested low risks for wheat regions across Queensland and relatively low risks for most regions across New South Wales, except for earlier planting with quick-maturing varieties. However, for fixed sowing dates of 1 May and 1 June and varying maturity types, the combined footprints for moderate-risk and high-risk categories ranged from 34% to 99% of the broad wheat region for South Australia, from 12% to 97% for Victoria, and from 9% to 59% for Western Australia. A further research component aims to conduct a field validation to improve quantification of the range of LMA triggering conditions; this would improve the predictive LMA framework and could assist industry with future decision-making based on a quantifiable LMA field risk.

Quality seed is a prerequisite to uniform stand establishment, which contributes to higher crop yield. However, prevalence of poor-quality cottonseed with high moisture content due to suboptimal harvesting and postharvest practices is the primary reason for crop-stand failure in developing countries. The present study evaluated the effects of harvesting environment, drying method and storage conditions on seed quality of transgenic (FH-142) and non-transgenic (FH-942) genotypes of cotton (Gossypium hirsutum L.) cultivated in Pakistan. Both genotypes were picked three times at monthly intervals during the cropping season and subjected to a ginning process. Seed was then dried in the sun or with desiccant zeolite beads, and stored for 5 months in cloth or hermetic bags at room temperature or in paper bags at 10°C. The efficiency of storage systems was evaluated by estimating moisture content and germination potential periodically in the storehouse and later under field conditions. Both genotypes exhibited better seed quality attributes at the first picking, and zeolite beads dried seed to lowest moisture content more quickly than sun-drying. Seeds of both genotypes stored hermetically retained the lowest moisture content, maximum germination potential, and lower fatty acid contents throughout the storage period, as well as performing significantly better in the field by exhibiting early and uniform stand establishment, more fruiting branches and bolls, and higher yield. Thus, use of zeolite beads in post-harvest drying followed by hermetic storage preserves cottonseed quality for longer, and leads to improved crop growth and yield of cotton. These practices will be useful for cotton farmers in developing countries.

This study reviews published information on the tactical management decisions needed to maximise economic grain yield in winter-dominant rainfall regions of the Mediterranean type. Tactical decisions are defined as those relating to the period from immediately before sowing to harvest. Tactical management is the principal means by which farmers respond to changing environmental and short-term economic conditions as the season progresses. The review considers published evidence that underpins these decisions and relates to cereal crops (wheat, barley and oats), pulse crops (field pea, faba bean, chickpea and narrow-leaved lupin) and canola. The criteria used to guide management decisions during the season involve soil and tissue tests for nutrients, knowledge of weed numbers and resistance status in the current and previous seasons, weather conditions that favour disease development, and knowledge of thresholds and biology of insect pests that may warrant control measures. All of these decisions can be related to the timing of the opening rains and the length of the growing season; the crop, pasture or weeds present in the previous two seasons; the presence of pest- and disease-bearing crop residues; and the type of tillage in use. Most of these indicators require further refinement through research across environments, soil types, crop types and production systems. The likely interactions between tactical or short-term management decisions, longer term or strategic decisions, and genetic factors are discussed. The prevalent use of chemicals in the management of biotic factors that can impact the crops is noted, as is progress towards various systems of ‘integrated’ management of these threats to crop production. Most tactical decisions in rainfed cropping systems appear to be supported by adequate evidence, although some decisions are still based on practical experience and observations. Application of tactical management practices together with strategic management and use of improved genotypes provides the possibility of achieving rainfall-limited potential grain yield at a regional scale. The papers reviewed have been selected partly on the basis that the experimental treatments achieved the estimated potential grain yield. Where the potential grain yields are not being achieved in commercial crops, it remains unclear whether this is due to inadequate adoption of existing information or inadequate research to identify and address the underlying causes. We highlight the need to devise a simple decision aid to assist farmers and their advisers to respond to the variable seasonal conditions evident since the turn of the Century.

Chickpea (Cicer arietinum L.) is an important grain legume that is grown and consumed all over the world. Chickpea is mostly grown in rainfed areas and marginal soils with low available zinc (Zn); however, its productivity is affected by micronutrient deficiencies in soil, particularly Zn deficiency. Zinc is a structural constituent and regulatory cofactor of enzymes involved in various plant biochemical pathways. As such, Zn deficiency impairs plant growth and development by reducing enzyme activity, disturbing ribosomal stabilisation, and decreasing the rate of protein synthesis. Moreover, Zn deficiency induces flower abortion and ovule infertility, leading to low seedset and substantial yield reductions. Nonetheless, inclusion of chickpea in cropping systems (e.g. rice–wheat), either in rotation or intercropped with cereals, improves Zn availability in the soil through the release of phosphatases, carboxylates, and protons by roots and soil microbes. This review discusses the role of Zn in chickpea biology, various factors affecting Zn availability, and Zn dynamics in soil and chickpea-based cropping systems. The review also covers innovative breeding strategies for developing Zn-efficient varieties, biofortification, and agronomic approaches for managing Zn deficiency in chickpea. Strategies to improve grain yield and grain Zn concentration in chickpea through use of different Zn-application methods—soil, foliar and seed treatments—that are simple, efficient and cost-effective for farmers are also discussed. Screening of efficient genotypes for root Zn uptake and translocation to the grain should be included in breeding programs to develop Zn-efficient chickpea genotypes.

Cotton cropping systems in Australia have poor nitrogen (N) use efficiency, largely due to over-application of N fertiliser. The N mineralisation from soil organic N reserves is often overlooked, or underestimated despite recent studies indicating that it may contribute the majority of N exported with the crop. Predicting N mineralisation is a major challenge for agricultural industries worldwide, as direct measurements are time-consuming and expensive, but there is considerable debate as to the most reliable methods for indirect estimation. Additionally, laboratory incubations assess potential (rather than actual) mineralisation, and may not be representative of N cycling rates in the field. We collected 177 samples from most major Australian cotton growing regions, and assessed their mineralisation potential using ex situ laboratory incubations, along with an assessment of potential indicators routinely measured in soil nutrient tests. Additionally, at three unfertilised sites we conducted in situ assessment of mineralisation by quantifying soil N at the beginning of the growing season, and soil and crop N at the end of the season. We found that Australian cotton cropping soils had substantial mineralisation potential, and that soil total N and total carbon were correlated with mineralisation, and have potential to be used for prediction. Other potential indicators such as carbon dioxide production and ammonium and nitrate concentrations were not correlated with mineralisation. In parallel studies of ex situ and in situ mineralisation, we found ex situ laboratory incubations overestimated mineralisation by 1.7 times on average. We discuss findings in terms of management implications for Australian cotton farming systems.

Flocks of brolgas (Antigone rubicunda) and Australian sarus cranes (A. antigone gillae) congregate in cropping areas of the Atherton Tablelands in north Queensland, Australia, during the non-breeding months of May to December each year and sometimes come into conflict with farmers. The central part of the region has been declared a Key Biodiversity Area, largely because it is the only well known non-breeding area for the Australian sarus crane. We investigated spatial and temporal patterns of use of this landscape for foraging by the two species to determine how they might be affected by changes in cropping. Abundances of the species were positively correlated with each other over both time and space. Sarus cranes were nevertheless markedly more abundant on the fertile volcanic soils of the central Tablelands, whilst brolgas were more abundant on a variety of soils in outlying cropping areas close to roost sites, especially in the south-west of the region. Both species used a wide variety of crops and pastures but occurred at highest densities on ploughed land and areas from which crops (especially maize) had been harvested. In addition, brolgas were also strongly associated with early-stage winter cereals with volunteer peanuts from the previous crop. We conclude that maize and peanut crops are important as foraging sites for both species during the non-breeding season, a situation that requires management in the interest of both cranes and farmers, especially as cropping patterns intensify and agricultural technology changes. However, we also note that flocking on the Atherton Tablelands indicates that brolgas and sarus cranes are likely to be adaptable to change and able to take advantage of newly created cropping areas.

An improved ability to predict pasture dry matter (DM) yield response to applied phosphorus (P), potassium (K) and sulfur (S) is a crucial step in determining the production and economic benefits of fertiliser inputs and the environmental benefits associated with efficient nutrient use. The adoption and application of soil testing can make substantial improvements to nutrient use efficiency, but soil test interpretation needs to be based on the best available and most relevant experimental data. This paper reports on the development of improved national and regionally specific soil test–pasture yield response functions and critical soil test P, K and S values for near-maximum growth of improved pastures across Australia. A comprehensive dataset of pasture yield responses to fertiliser applications was collated from field experiments conducted in all improved pasture regions of Australia. The Better Fertiliser Decisions for Pastures (BFDP) database contains data from 3032 experiment sites, 21918 yield response measures and 5548 experiment site years. These data were converted to standard measurement units and compiled within a specifically designed relational database, where the data could be explored and interpreted. Key data included soil and site descriptions, pasture type, fertiliser type and rate, nutrient application rate, DM yield measures and soil test results (i.e. Olsen P, Colwell P, P buffering, Colwell K, Skene K, exchangeable K, CPC S, KCl S). These data were analysed, and quantitative non-linear mixed effects models based upon the Mitscherlich function were developed. Where appropriate, disparate datasets were integrated to derive the most appropriate response relationships for different soil texture and P buffering index classes, as well as interpretation at the regional, state, and national scale. Overall, the fitted models provided a good fit to the large body of data, using readily interpretable coefficients, but were at times limited by patchiness of meta-data and uneven representation of different soil types and regions. The models provided improved predictions of relative pasture yield response to soil nutrient status and can be scaled to absolute yield using a specified maximal yield by the user. Importantly, the response function exhibits diminishing returns, enabling marginal economic analysis and determination of optimum fertiliser application rate to a specific situation. These derived relationships form the basis of national standards for soil test interpretation and fertiliser recommendations for Australian pastures and grazing industries, and are incorporated within the major Australian fertiliser company decision support systems. However, the utility of the national database is limited without a contemporary web-based interface, like that developed for the Better Fertiliser Decisions for Cropping (BFDC) national database. An integrated approach between the BFDP and the BFDC would facilitate the interrogation of the database by advisors and farmers to generate yield response curves relevant to the region and/or pasture system of interest and provides the capacity to accommodate new data in the future.

Herbicide-resistant weeds have prompted the development of non-chemical weed-control techniques for sustainable crop production. We examined the potential of pre-emergence microwave (MW) soil treatment to suppress weeds and enhance grain yield in rice (Oryza sativa L.) cropping in two agro-ecological zones of Australia. An experimental MW weed killer, which has four, independently controlled, 2-kW MW generators operating at 2.45 GHz, was used to treat the soil before cropping under field conditions. A once-off MW soil treatment (duration 60 s) and an untreated control were assigned in a randomised complete block design with five replicates at two study locations: Dookie (Victoria) and Jerilderie (New South Wales). Simpson’s numerical surface integral approximation estimated the applied energy density of ~500 J cm–2. This energy increased the soil’s temperature up to 70–75°C in top soil horizon (0–6 cm) as depicted by infrared thermal imaging. No statistically significant difference was detected for weed control between MW and untreated control plots at either study location. At Dookie, grain yield did not significantly increase in response to MW soil treatment, whereas at Jerilderie, grain yield was 20% higher (P < 0.05) with MW soil treatment than in control plots. At Jerilderie, the irrigation water use efficiency (t ML–1) was 21% higher in MW plots than control plots. In summary, MW exposure of 60 s appeared to be an insufficient heating duration for seedbank depletion. This suggests further treatment modification followed by rigorous testing under different soils conditions using the MW prototype.

Low levels of plant-available micronutrients were an inherent feature of many agricultural soils in Australia, mostly due to the prevalence of highly weathered soil parent materials. The diagnosis and correction of the widespread deficiencies of micronutrients, especially copper (Cu), molybdenum (Mo) and zinc (Zn), were prerequisites for the development of productive, legume-based pastures in southern Australia. In subtropical and tropical regions, Mo deficiency commonly limited pasture-legume production. Soil treatments involving micronutrient fertiliser incorporated in soils, or applied as additives to superphosphate, were generally effective in alleviating micronutrient deficiencies. In the low-output dryland pasture systems, the annual removal of micronutrients in wool and meat is small compared with rates added in fertiliser. Hence, in general, the residues of soil-applied micronutrient fertilisers remain effective for many years, for example, up to 30 years for Cu. By contrast, shorter residual values occur for manganese (Mn) fertiliser on highly calcareous soils, and for Zn in high-output pasture systems such as intensive dairy production. In the last two decades since the recommendations for micronutrient management of pastures were developed, there have been many changes to farming systems, with likely implications for micronutrient status in pastures. First, increased cropping intensity and low prices for wool and meat have meant lower nutrient inputs to pastures or to the pasture phase of rotations with crops. However, when pastures have been rotated with crops, ongoing small additions of Cu, Zn and Mo have been common. In cropping phases of farming systems, lime application and no-till may have altered the chemical and positional availability of micronutrients in soils to pastures. However, there has been little study of the impacts of these farming-systems changes on micronutrient status of pastures or profitability of the production system. The intensification of dairy production systems may also have altered the demand for, and removal rates of, micronutrients. Soil tests are not very reliable for Mn or Mo deficiencies, and well-calibrated soil tests for boron, Cu and Zn have been developed only for limited areas of pasture production and for a limited range of species. There is limited use of plant tests for nutrient management of pastures. In conclusion, there is limited knowledge of the current micronutrient status of pastures and their effects on animal health. Pasture production would benefit from targeted investigation of micronutrients status of pasture soils, pasture plants and micronutrient-linked animal-health issues.

The rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system is the largest agricultural production system worldwide, and is practised on 24 Mha in Asia. Many factors have threatened the long-term sustainability of conventional rice–wheat cropping systems, including degradation of soil health, water scarcity, labour/energy crises, nutrient imbalances, low soil organic matter contents, complex weed and insect flora, the emergence of herbicide-resistant weeds, and greenhouse-gas emissions. Options for improving the yield and sustainability of the rice–wheat cropping system include the use of resource-conservation technologies such as no-till wheat, laser-assisted land levelling, and direct-seeded aerobic rice. However, these technologies are site- and situation-specific; for example, direct-seeded aerobic rice is successful on heavy-textured soils but not sandy soils. Other useful strategies include seed priming, carbon trading and payment, the inclusion of legumes, and eco-friendly and biological methods of weed control. Irrigation based on soil matric potential using tensiometers can be useful for saving surplus water in direct-seeded, aerobic rice. These options and strategies will contribute to resolving water scarcity, saving labour and energy resources, reducing greenhouse-gas emissions, increasing soil organic matter contents, and improving the soil-quality index. Seed priming with various substances that supplement osmotic pressure (osmotica) is a viable option for addressing poor stand establishment in conservation rice–wheat cropping systems and for increasing crop yields. To strengthen the campaign for using resource-conservation technologies in rice–wheat cropping systems, carbon-payment schemes could be introduced and machinery should be offered at affordable prices. The persistent issue of burning crop residues could be resolved by incorporating these residues into biogas/ethanol and biochar production. Because rice and wheat are staple foods in South Asia, agronomic biofortification is a useful option for enhancing micronutrient contents in grains to help to reduce malnutrition.

Echinochloa colona and E. crus-galli are two important annual grass weeds distributed throughout the summer cropping regions of Australia. Both species are highly problematic weeds, responsible for yield losses of up to 50% in summer grain crops. The success of Echinochloa species as weeds is attributed to their rapid growth, prolific seed production, seed dormancy and adaptability to a wide range of environments. Importantly, E. colona has evolved resistance to glyphosate in Australia, with resistant populations now widespread across the summer cropping regions. Fallow management of E. colona with glyphosate alone is risky in terms of increasing the chance of resistance and highly unsustainable; other control strategies (residual herbicides, strategic tillage, etc.) should be considered to complement herbicides. This review provides a summary of current information on the biology, ecology and management of Echinochloa species. The knowledge gaps and research opportunities identified will have pragmatic implications for the management of these species in Australian grain cropping systems.

Annual ryegrass (Lolium rigidum Gaud.) is a troublesome invasive plant in southern Australian cropping systems and is typically infected with a fungal endophyte, Epichloë occultans. Potential links between herbicide resistance and endophyte infection were investigated in this study. We surveyed 391 ryegrass populations from geographically distinct, naturalised pasture and cropping areas across southern Australia and compared frequencies of seed-borne endophyte infection in the collected seed samples from mature annual ryegrass. Data on herbicide resistance from similar seedlots were cross-referenced with endophyte infection frequency to examine the potential relationship between herbicide resistance and endophyte infection. Seeds from cropping paddocks exhibited a significantly higher frequency of endophyte infection than pasture paddocks sampled from the same region. Frequencies of endophyte infection in annual ryegrass declined across Australia during 2001–09, whereas the opposite trend was observed during 2009–12. Impacts of the Australian Millennium Drought, the correspondingly altered rainfall patterns and environmental selection pressures have a role in determining observed endophyte infection frequencies. However, there was no significant correlation between endophyte frequency and herbicide resistance in the populations evaluated. Differences in endophyte infection frequencies were associated with farming practices, and require further examination to determine causative selection pressures encountered in Australian field settings.

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.

In New Zealand, pastoral soils have substantial organic carbon (OC) stocks, which may be vulnerable to loss from disturbance and environmental perturbations. We assessed OC vulnerability using two approaches. For the first approach, we postulated that the OC deficit of continuously cropped soils relative to nearby pastoral soils would provide a measure of the quantity of potentially vulnerable OC in pastures. As a test, soils were sampled to a depth of 15 cm at 149 sites and the total organic carbon (TOC) and particulate organic carbon (POC) contents were measured. The second approach involved measurement of OC mineralisation in a laboratory assay (98 day aerobic incubation at 25°C). For the pastoral soils, the mean TOC and POC was about twice that of the cropped soils. On average, 89% more OC was mineralised from the pastoral soils compared with the cropped counterparts. However, the quantity of OC mineralised in pasture soils was small relative to the potential for OC loss inferred from the difference in TOC between pastoral and cropped soils. Carbon mineralisation was explained using a two-pool exponential model with rate constants of the ‘fast’ and ‘slow’ pools equating to 0.36 ± 0.155 and 0.007 ± 0.003 day–1 respectively. The larger, slow OC pool correlated strongly with hot water extractable OC whereas the fast pool was related to OC extracted using cold water. Our results suggest that water extraction (using cold and hot water) can provide a rapid estimate of the quantity of mineralisable OC across a wide range of New Zealand soils.

Taking into account the relationship between rainfall and temperature, 64% of the Spanish territory can be classified as arid (25%) or semiarid (39%). In these areas, vegetal surface includes permanent pastures and drought grasslands (34.0%), fallows (13.4%), winter cereals for grain production (21.2%), forage crops (mainly lucerne, and winter cereals harvested as green forage; 2.6%) and woodland hills. Ruminants in these zones account for 15.4 million head, of which nearly 80% are sheep. In the present paper, the possibilities of integrating sheep in cropping systems are discussed, and an alternative based on the use of permanent sowed prairies (lucerne), self-sowing annuals (Wimmera ryegrass) and winter cereals (barley) will be analysed.

Effective management of fertiliser nitrogen (N) inputs by farmers will generally have beneficial productivity, economic and environmental consequences. The reality is that farmers may be unsure of plant-available N levels in cropping soils at sowing and make decisions about how much fertiliser N to apply with limited information about existing soil N supply. NBudget is a Microsoft (Armonk, NY, USA) Excel-based decision support tool developed primarily to assist farmers and/or advisors in Australia’s northern grains region manage N. NBudget estimates plant-available (nitrate) N at sowing; it also estimates sowing soil water, grain yields, fertiliser N requirements for cereals and oilseed crops and N2 fixation by legumes. NBudget does not rely on soil testing for nitrate-N, organic carbon or soil water content. Rather, the tool relies on precrop (fallow) rainfall data plus basic descriptions of soil texture and fertility, tillage practice and information about paddock use in the previous 2 years. Use is made of rule-of-thumb values and stand-alone or linked algorithms describing, among other things, rates of mineralisation of background soil organic N and fresh residue N. Winter and summer versions of NBudget cover the 10 major crops of the region: bread wheat, durum, barley, canola, chickpea and faba bean in the winter crop version; sorghum, sunflower, soybean and mung bean in the summer crop version. Validating the winter crop version of NBudget estimates of sowing soil nitrate-N against three independent datasets (n=65) indicated generally close agreement between measured and predicted values (y=0.91x+16.8; r2=0.78). A limitation of the tool is that it does not account for losses of N from waterlogged or flooded soils. Although NBudget also predicts grain yields and fertiliser N requirements for the coming season, potential users may simply factor predicted soil N supply into their fertiliser decisions, rather than rely on the output of the tool. Decisions about fertiliser N inputs are often complex and are based on several criteria, including attitudes to risk, history of fertiliser use and costs. The usefulness and likely longevity of NBudget would be enhanced by transforming the current Excel-based tool, currently available on request from the author, to a stand-alone app or web-based tool.

Many farmers in Australia and in other countries have a choice of crop or livestock production, and many choose a mixture of both, based on risk preference, personal interests, markets, land resources and local climate. Mixed farming can be a risk-spreading strategy, especially in highly variable climates, but the right scales of each enterprise within the mix may be critical to farm profitability. To investigate expected farm profits, the probability of breaking even, as well as the worst and best case scenarios, we used farm data and APSIM (Agricultural Production Systems Simulator) to simulate the production of a typical, semi-arid, mixed-farm in southern Queensland. Three farming system scenarios were investigated: I, livestock and more intensive cropping; II, current production system of livestock and minimal cropping; and III, livestock only. We found that the expected profits were in the order system I > system III > system II. The key reason for the lower profits of system II was the high overhead cost of capital to continue some cropping, with low annual cropping income. Under the worst case scenario, in years with low rainfall, system I had the greatest downside risk with far greater financial losses. Systems I and III had similar probabilities of breaking even, and higher than system II, which incurs cropping overheads and limited cropping returns. Therefore, system II was less desirable than either system I or III. This case study helps farmers and advisors of semi-arid mixed farming enterprises to be better informed when making decisions at the paddock and whole-farm level, in both the short and long term, with respect to profit and risk. The method used in this paper can be applied to other mixed farms, in Australia and elsewhere.

This study benchmarked N2O and CO2 emissions in heavily (>1 Nitrogen t annually) manured and fertilised sandy soils in temperate Australia and demonstrated the mitigation of N2O emissions using the nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP). Three field trials conducted on celery crops from 2014 to 2016 showed that the traditional practice of adding composted chicken manure (4.5–8.0 t ha–1) to the surface of sandy soils produced large spikes in daily emissions of N2O (up to 1860 g ha–1 day–1) and that further spikes occurred with each subsequent fertiliser application. Pre-crop incorporation of manure (8–9 t ha–1) rather than surface application reduced the daily N2O-N emission flux from 1800 to

Rainfed farms in south-eastern Australia often combine annual cropping and perennial pasture phases with grazing sheep enterprises. Such diversity serves in managing diseases, pests and plant nutrition while stabilising income in the face of wide, uncorrelated variations in international commodity prices and local weather over time. We use an actuarial accounting approach to capture the above contexts to render financial risk profiles in the form of distributions of decadal cash balances for a representative 1000-ha farm at Coolamon (34°50ʹS, 147°12ʹE) in New South Wales, Australia. For the soil and weather conditions at this location we pose the question of which approach is better when establishing the perennial pasture lucerne (Medicago sativa L.): sowing with the final crop of the cropping phase, or sowing alone following the final crop? It is less expensive to sow lucerne with the final crop, which can provide useful income from the sale of grain, but this practice can reduce pasture quantity and quality in poorer years. Although many years of field research have confirmed that sowing lucerne alone is the most reliable way to establish a pasture in this area, and years of extension messages to this effect have gone out to farmers, they often persist in sowing lucerne with their final cereal crops. For this region, counting all costs, we show that sowing lucerne alone can reduce farm financial risk (i.e. probability of negative decadal cash balances) at stocking rates >10 dry sheep equivalents (DSE)/ha, compared with the practice of sowing lucerne with a cover crop. Establishing lucerne alone allows the farmer the option to profitably run higher stocking rates for higher median decadal cash margins without additional financial risk. At low stocking rates (i.e. 5 DSE/ha), there appears to be no financial advantage of either establishment approach. We consider the level of equity, background farm debt and overhead costs to demonstrate how these also affect risk-profile positions of the two sowing options. For a farm that is deeply in debt, we cannot suggest either approach to establishing lucerne will lead to substantially better financial outcomes.

Greenhouse gas abatement in the agricultural cropping industry can be achieved by employing management practices that sequester soil carbon (C) or minimise nitrous oxide (N2O) emissions from soils. However, C sequestration stimulates N2O emissions, making the net greenhouse-gas abatement potential of management practices difficult to predict. We studied land-management practices that have potential to mitigate greenhouse gas emissions by increasing soil C storage and/or decreasing soil N2O emissions for a diverse range of broadacre grain cropping sites in New South Wales. Carbon sequestration and N2O emissions were simulated with the Agricultural Production Systems Simulator (APSIM) for a baseline crop-management scenario and alternative scenarios representing management practices for greenhouse gas abatement, for 15 rainfed or irrigated sites. The global warming potential of the scenarios was quantified at 25 and 100 years after commencement of the alternative practices. Soil C and N2O emissions were predicted to increase with the use of practices that increased organic matter additions to the soil (e.g. adding a summer crop to the rotation). However, in only a few cases did the increase in soil C storage counter the N2O emissions sufficiently to provide net greenhouse gas abatement. For rainfed sites, inclusion of a summer crop and/or a pasture in the rotation was predicted to provide greenhouse gas abatement after 25 years, whereas after 100 years, only practices that included a summer crop provided abatement for some sites. For irrigated sites after 25 years, practices that reduced N fertiliser rate while retaining stubble were predicted to provide small abatement, and practices that included a summer crop provided abatement for some sites. After 100 years, practices likely to provide abatement included those that reduced N2O emissions, such as reducing N fertiliser rate. These findings suggest that a few management practices are likely to abate greenhouse gas emissions across New South Wales grain production sites and that these practices differ for irrigated and rainfed sites.

Acacia harpophylla F.Muell. ex Benth. (brigalow) forests and woodlands formerly occupied at least 8.7 M ha of Queensland and New South Wales, but less than 10% persists in isolated fragments and linear strips within a matrix of exotic beef pasture and dryland cropping. Given the relatively rapid and widespread clearing of brigalow forests, recent research has focussed on restoration via naturally resprouting vegetation. However, our understanding of A. harpophylla sexual reproduction and seedling recruitment remains poor. This study, undertaken following a widespread masting event in late 2007, aimed to (1) quantify initial densities of A. harpophylla germinants; (2) estimate subsequent seedling survival during the first year; and (3) determine minimum size thresholds for sexual reproduction in A. harpophylla. Initial densities averaged >46 000 seedlings ha–1, but only 438 seedlings ha–1 (

Despite the potential productivity benefits, intercrops are not widely used in modern, mechanised grain cropping systems such as those practised in Australia, due to the additional labour required and the added complexity of management (e.g. harvesting and handling of mixed grain). In this review we investigate this dilemma using a two-dimensional matrix to categorise and evaluate intercropping systems. The first dimension describes the acquisition and use of resources in complementary or facilitative interactions that can improve resource use efficiency. The outcome of this resource use is often quantified using the land equivalent ratio (LER). This is a measure of the relative land area required as monocultures to produce the same yields as achieved by an intercrop. Thus, an LER greater than 1 indicates a benefit of the intercrop mixture. The second dimension describes the benefits to a farming system arising not only from the productivity benefits relating to increased LER, but from other often unaccounted benefits related to improved product quality, rotational benefits within the cropping system, or to reduced business risks. We contend that a successful intercrop must have elements in both dimensions. To date most intercropping research has considered only one of these two possible dimensions. Intercrops in large, mechanised, rain-fed farming systems can comprise those of annual legumes with non-legume crops to improve N nutrition, or other species combinations that improve water use through hydraulic redistribution (the process whereby a deep-rooted plant extracts water from deep in the soil profile and releases a small proportion of this into the upper layers of the soil at night), or alter disease, pest or weed interactions. Combinations of varieties within cereal varieties were also considered. For our focus region in the southern Australian wheatbelt, we found few investigations that adequately dealt with the systems implications of intercrops on weeds, diseases and risk mitigation. The three main intercrop groups to date were (1) ‘peaola’ (canola-field pea intercrops) where 70% of intercrops (n = 34) had a 50% productivity increase over the monocultures, (2) cereal-grain legume intercrops (n = 22) where 64% showed increases in crop productivity compared with monocultures and (3) mixtures of cereal varieties (n = 113) where there was no evidence of a productivity increase compared with the single varieties. Our review suggests that intercropping may have a role in large rain-fed grain cropping systems, based on the biophysical benefits revealed in the studies to date. However, future research to develop viable intercrop options should identify and quantify the genotypic differences within crop species for adaptation to intercropping, the long-term rotational benefits associated with intercrops, and the yield variability and complexity-productivity trade-offs in order to provide more confidence for grower adoption. Farming systems models will be central to many of these investigations but are likely to require significant improvement to capture important processes in intercrops (e.g. competition for water, nutrients and light).

The inland Pacific Northwestern USA (iPNW) wheat-producing region has a diversity of environments and soils, yet it lacks crop diversity and is one of the few semi-arid wheat-growing regions without significant integration of oilseeds. Four major agroecological zones, primarily characterised by water availability, feature distinctly different fallowed and annually cropped systems, each presenting different challenges and opportunities to integrate winter and spring canola. Although major interests in regional energy crops and rotational diversification spurred feasibility research on iPNW canola food, feed and fuel production in the 1970s, commercial canola adaptation has lagged behind other semi-arid wheat regions for various socioeconomic, ecophysiological and agronomic reasons. New federal crop insurance policies will reduce economic risks in new crop adaptation, and oilseed processing facilities are creating new local markets. Although canola management largely relies on wheat farm equipment, agronomic approaches require strategic adjustments to account for physiological differences between canola and cereals including seed size, seedling morphology and responses to temperature extremes. Climate change predictions for the region threaten to exacerbate current hot and dry summers and research aims to develop and adapt flexible winter and spring canola-based systems to regional water and temperature stressors in each zone. Adaptation will require novel planting, fertilisation and weed control strategies to successfully establish improved winter canola cultivars in hot dry summers that survive cold winters, and spring canola cultivars direct-seeded in cool wet springs. The adaptation of winter and spring canola will somewhat mirror the rotational placement of winter and spring cereals within each zone. Economic analysis of oilseed break crop benefits such as weed and disease control will help to demonstrate the medium-term economic benefits of crop diversification to support the growth of a regional canola industry in the iPNW.

Frost damage remains a major problem for broadacre cropping, viticulture, horticulture and other agricultural industries in Australia. Annual losses from frost events in Australian broadacre agriculture are estimated at between $120 million and $700 million each year for this sector. Understanding the changing nature of frost risk, and the drivers responsible, are important steps in helping many producers manage climate variability and change. Our analysis, using Stevenson screen temperature thresholds of 2°C or below as an indicator of frost at ground level, demonstrates that across southern Australia, despite a warming trend of 0.17°C per decade since 1960, ‘frost season’ length has increased, on average, by 26 days across the whole southern portion of Australia compared with the 1960–1990 long-term mean. Some areas of south-eastern Australia now experience their last frost an average 4 weeks later than during the 1960s. The intersection of frost and wheat production risk was quantified at 60 sites across the Australian wheatbelt, with a more in-depth analysis undertaken for 15 locations across Victoria (i.e. eight sites common to both the National and Victorian assessments and seven sites exclusive to the Victorian analysis). The results of the national assessment highlight how frost-related production risk has increased by as much as 30% across much of the Australian wheatbelt, for a range of wheat maturity types, over the last two decades, in response to an increase in later frost events. Across 15 Victorian sites, sowing dates to achieve anthesis during a period with only a 10% chance of a 0°C night occurring shifted by 23 days (6 June) for the short-season variety, 20 days (17 May) for the medium-season variety and 36 days later (9 May) for the long-season variety assessed.

The high-rainfall zone (HRZ) of southern Australia is the arable areas where annual rainfall is between 450 and 800 mm in Western Australia and between 500 and 900 mm in south-eastern Australia, resulting in a growing-season length of 7–10 months. In the last decade, there has been a growing recognition of the potential to increase crop production in the HRZ. We combined (1) a survey of 15 agricultural consultants, each of whom have ~40–50 farmer clients across the HRZ, (2) 28 farm records of crop yields and area for 2000–2010, (3) 86 wheat and 54 canola yield observations from well managed experiments, and (4) long-term simulated crop yields at 13 HRZ locations, to investigate recent trends in crop production, quantify the gap between potential and actual crop yields, and consider the factors thought to limit on-farm crop yields in the HRZ. We found in the past 10 years a trend towards more cropping, particularly in WA, an increased use of canola, and advances in the adaptation of germplasm to HRZ environments using winter and longer-season spring types. Consultants and the farm survey data confirmed that the rate of future expansion of cropping in the HRZ will slow, especially when compared with the rapid changes seen in the 1990s. In Victoria, New South Wales and South Australia the long-term water-limited potential yield in HRZ areas, as measured by experimental yields, consultant estimates and simulations for slow developing spring cultivars of wheat and canola was 5–6 and 2–3 t/ha for a decile 5 season. For Western Australia it was 4–5 and 2–3 t/ha, where yields were less responsive to good seasons than in the other states. The top performing farmers were achieving close to the water-limited potential yield. There are yield advantages of ~2 t/ha for ‘winter’ over ‘spring’ types of both wheat and canola, and there is scope for better adapted germplasm to further raise potential yield in the HRZ. Consultants stated that there is scope for large gains in yield and productivity by encouraging the below-average cropping farmers to adopt the practices and behaviours of the above-average farmers. The scope for improvement between the below- and above-average farmers was 1–3 t/ha for wheat and 0.5–1.5 t/ha for canola in a decile 5 season. They also stated that a lack of up-to-date infrastructure (e.g. farm grain storage) and services is constraining the industry’s ability to adopt new technology. Priorities for future research, development and extension among consultants included: overcoming yield constraints where growing-season rainfall exceeds 350 mm; adaptation of winter and long-season spring types of cereals and canola and management of inputs required to express their superior yield potential; and overcoming barriers to improved planning and timeliness for crop operations and adoption of technology.

Nitrous oxide (N2O) emissions from Australian grain cropping systems are highly variable due to the large variations in soil and climate conditions and management practices under which crops are grown. Agricultural soils contribute 55% of national N2O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N2O emissions, yield and emissions intensity in a range of management practices in grain crops across eastern Australia with the Agricultural Production Systems sIMulator (APSIM). The model was initially evaluated against experiments conducted at six field sites across major grain-growing regions in eastern Australia. Measured yields for all crops used in the experiments (wheat, barley, sorghum, maize, cotton, canola and chickpea) and seasonal N2O emissions were satisfactorily predicted with R2=0.93 and R2=0.91 respectively. As expected, N2O emissions and emissions intensity increased with increasing nitrogen (N) fertiliser input, whereas crop yields increased until a yield plateau was reached at a site- and crop-specific N rate. The mitigation potential of splitting N fertiliser application depended on the climate conditions and was found to be relevant only in the southern grain-growing region, where most rainfall occurs during the cropping season. Growing grain legumes in rotation with cereal crops has great potential to reduce mineral N fertiliser requirements and so N2O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N2O mitigation.

Avena is a problematic weed of cropping regions of southern Australia and many areas of the world. In 2010, a random survey was conducted across 14 million hectares of the Western Australian grain belt to monitor the change in herbicide resistance levels by comparing resistance frequency results with a survey conducted in 2005. Screening Avena populations with herbicides commonly used to control this weed revealed that 48% of Avena populations displayed resistance to the commonly used acetyl-Co A carboxylase-inhibiting herbicides, which was lower than that found in 2005 (71%). The broad-spectrum herbicides glyphosate and paraquat provided good control of all Avena populations. Resistance to acetolactate synthase-inhibiting herbicides and to flamprop were detected for the first time in Western Australia in this survey. Therefore, a wide range of weed management options that target all phases of the cropping program are needed to sustain these cropping systems in the future.

Technologies such as minimum tillage and new herbicides have enabled the use of early and dry sowing in Western Australia (WA). Although there is a sowing date that maximises yield of individual fields, on-farm sowing dates are constrained by the availability of machinery and labour. It was hypothesised that farms with a larger crop area would begin sowing earlier and be more likely to dry sow than smaller farms because they would take longer to sow. Current sowing dates and the extent of dry sowing in WA were explored using multiple analytical approaches, such as analysis of farm records, survey data and historical weather records, and simulation modelling. Field records from seven farms showed that sowing date of the first cereal crop on-farm had advanced markedly in recent years. The timeline of this advanced cereal sowing date differed across sites but was prominent from 2010 for most sites. In a larger survey, conducted between 2011 and 2014, of 805 grain farms across all rainfall zones in the WA grain belt, the mean first crop sowing date was 29 April and half the farms used dry sowing. Farms with larger cropped areas tended to begin sowing crops earlier and were more likely to dry sow. Only 26% of small farms (5000 ha crop). A larger proportion of lupin (34%) and canola (43%) was sown dry than wheat (16%) or barley (10%; P

In Queensland, Australia, large tracts of native vegetation have been cleared for agriculture, resulting in substantial hydrological changes in the landscape. Australia’s longest-running paired catchment study, the Brigalow Catchment Study (BCS), was established in 1965 to monitor hydrological changes associated with land development, particularly that of the 1960s Land Development Fitzroy Basin Scheme. The BCS has unequivocally shown that developing brigalow (Acacia harpophylla) for cropping or for grazing doubles runoff volume. However, to date little research had been undertaken to quantify the changes in peak runoff rate when brigalow is cleared for cropping or grazing. The present study compared peak runoff rates from three brigalow catchments, two of which were subsequently cleared for cropping and pasture. Prior to land development, average peak runoff rates from the three brigalow scrub catchments were 3.2, 5 and 2mmh–1 for catchments 1 to 3 respectively. After development, these rates increased to 6.6mmh–1 from the brigalow scrub control catchment (catchment 1), 8.3mmh–1 from the cropping catchment (catchment 2) and 5.6mmh–1 from the pasture catchment (catchment 3). Peak runoff rate increased significantly from both the cropping and pasture catchments after adjusting for the underlying variation in peak runoff rate due to climatic variation between the pre- and post-development periods. The average peak runoff rate increased by 5.4mmh–1 (96%) for the cropping catchment and by 2.6mmh–1 (47%) for the pasture catchment. Increases in peak runoff rate were most prevalent in smaller events with an average recurrence interval of less than 2 years under cropping and 4 years under pasture.

Grazing sheep on cereal crops in winter has become widely adopted in medium–high-rainfall zones of Australia. Interest in this practice has spread to the lower rainfall parts of the cereal–livestock zone where it is being applied to shorter season crop varieties. A farm-system modelling study was conducted to investigate the value of deferment of annual pastures by grazing spring wheat in their place. The biophysical simulation model, based on a representative wheat and sheep farming system in the wheatbelt of Western Australia, involved two grazing-management scenarios and used climate data for the period 1962–2011 for three locations in Western Australia representing low-, medium- and high-rainfall cropping regions: Merredin, Wickepin and Kojonup. The grazing-management policy of the main scenario, ‘crop grazing’, placed livestock on the crops only until the crop reached Zadoks growth stage 30, provided the green biomass of the farm’s annual pastures was

Fast degrading and declining land, water availability, biodiversity, environment and other natural resources, together with shrinking farm returns and reduced crop productivity caused by continuous and intensive cultivation of rice-wheat systems, necessitate diversification of farming in Northern India. Integrated farming systems (IFS) involving animals (livestock, fish, etc.) and cropping (cereals, trees, etc.) are recognised as an alternative for preserving ecosystems and enhancing livelihood security. A study was therefore undertaken under Northern Indian conditions to develop IFS models for various sizes of farm and to compare these models with the existing rice-wheat system for sustainability and profitability. The IFS models were developed in single objective (using linear programming) and multi-objective (using compromise programming) frameworks. Multi-objective analysis provides deeper insight into the problem as it caters directly for the multi-faceted needs of the farmers. These parallel methodologies offer a novel approach to modelling IFS to draw different farming scenarios for comparison. The IFS strategies developed show the potential to generate a greater farm income than with existing rice-wheat cropping for all sizes of farm. The study revealed that IFS offer more perspectives for an economically viable and sustainable agriculture for typical farms in Northern India.

In cropping systems where one type of crop dominates for economic reasons, farmers may employ alternative cropping or pasture options for strategic purposes such as controlling weed populations, reducing crop disease, and accumulating soil nitrogen. Tactical decisions regarding break crops often involve understanding the economic implications of several interacting bio-physical factors, along with complex trade-offs between short-term benefits, such as immediate profit, and long-term ecological problems, such as increased weed seedbank. Modelling analysis regarding tactical crop-sequencing and break-crop decisions has generally not addressed these longer term dynamic factors. In this study we adapted an analysis and modelling framework (LUSO), originally designed to aid understanding of the long-term strategic planning of agricultural crop and pasture rotations, so that it can be used to analyse immediate tactical decisions regarding break crops and sequencing, while still accounting for both short- and long-term implications of these decisions. We show how the revised framework was applied to two example scenarios and demonstrate that in both cases it can be used for simple decision-support, as well as more in-depth analysis and insight into the factors influencing the immediate decision.

Mixed farming enterprises throughout the world balance and integrate crop and livestock enterprises to spread economic risk and capture synergies in terms of forage supply, but in many areas of the world these have become increasingly separated and specialised (Wilkins 2008).