Developing new and improved grazing systems for crop–livestock farms where crop production is the major driver of farm management decisions presents a unique research and development challenge. In southern Australia, a substantial proportion of animal production from grazing comes from regions and farms where cropping is the major enterprise. In this paper, we describe a multi-disciplinary farming-systems research approach (EverCrop) aimed at improving farm profitability, risk management and environmental impacts through the development and integration of new grazing options with an emphasis on perennial species. It has been used to analyse and target new opportunities for farmers to benefit from perennial species across dry Mediterranean-type and temperate regions of southern Australia. It integrates field experimentation, on-farm trialling, farmer participatory research, soil–plant–climate biophysical modelling, whole-farm bioeconomic analysis and evaluations of adoptability. Multi-functional roles for summer-active grasses with winter cropping, integration of forage shrubs and establishment of new mixes of perennial grasses in crop rotations to improve farming system performance are identified, along with an analysis of factors likely to affect rate of uptake by farmers.

Pastures continue to provide essential functions for the mixed-farming zone in south-eastern Australia, where crop and livestock production are integral parts of most farms. Establishment of pastures in this zone needs to be low-cost and preferably with minimal risk. Pastures are typically sown either directly or in combination with a cover-crop (also called undersowing; the practice of sowing pasture seed simultaneously with a crop that is intended for grain production in the first year), so that the establishment cost is offset by income from the sale of grain. The purposes of this review are to: (i) draw together the literature on undersowing pastures, including studies conducted since the previous review in 1965; (ii) understand why there is a discrepancy between research results that generally do not support the practice of undersowing pastures, whereas farmer preference appears to establish pastures under a cover-crop; and (iii) identify critical needs for further research to aid in making decisions about pasture establishment on-farm. Published and unpublished data from the Australian wheatbelt on establishing pastures by undersowing was examined from the 1920s to the present and included seven publications for perennial species from 26 different experiments. Eight publications addressing establishment of annual species were available from 30 experiments. Many trials appear to have been conducted without being analysed or published. A further 16 international publications were reviewed. Generally, cover-crops reduced annual pasture seedset and perennial density even though the pastures established under the cover-cropping were commonly deemed ‘satisfactory’ by the authors. Pasture establishment was improved by reducing the sowing rate of the cover-crop and/or sowing on alternate rows. Technological change during the past 25 years has led to different configurations of seeding machinery, increased use of herbicides and longer cropping phases. Conclusions previously reached may therefore need to be re-assessed. No data published quantified the risks associated with undersowing on a seasonal and regional basis to determine the probability of success, and there are insufficient data to model the complex physiological interactions between crop and pasture, with most experiments focused on basic agronomic parameters. Furthermore, long-term effects of establishment method on total pasture biomass production and subsequent effects on following crops have rarely been demonstrated, because of the short time-frames in which most experiments have been conducted. Farmers in the mixed-farming zone still prefer to establish pastures under a cover-crop because of perceived financial benefit of the practice. This review identifies substantial research gaps to be addressed to improve pasture-establishment decisions.

In 2009, 95 farmers in the mixed farming zone of southern New South Wales (NSW), average annual rainfall 450–700 mm, were surveyed about their use of perennial pasture species. Survey responses indicated that, on average, 52% of land was under crop, 29% contained perennial pasture and 19% annual pastures. The proportion of land sown to perennial pastures and the species used differed with rainfall. Farmers identified concerns about the cost of establishment and poor survival of perennial pasture species as constraints to wider adoption. The survey also revealed that cover-cropping (sowing pasture species under the final grain crop in a cropping phase) was the dominant method of pasture establishment. Large-scale, on-farm participatory experiments were sown with the farm machinery, three at Ariah Park and one at Brocklesby in southern NSW in 2009 (annual rainfall 100 mm less than long-term average), and a further two experiments (one at each location) commenced in 2010 (annual rainfall >200 mm above average). These experiments compared the effect of cereal cover-crop sowing rate (standard rates used by the collaborating farmer and half of the standard rate) on the establishment of the perennials lucerne (Medicago sativa), phalaris (Phalaris aquatica), cocksfoot (Dactylis glomerata), and chicory (Cichorium intybus) sown in different mixes and rates with various annual legume species. The persistence and productivity of individual species were monitored for 2 years after sowing. Results indicated little or no effect of the presence of a cover-crop on the initial establishment of any of the perennials, but pasture species survival were severely affected by cover-crop sowing rates as low as half of the farmer practice (10 kg barley or 12 kg wheat ha^–1) in 2009. Despite higher than average annual rainfall in 2010 and 2011, the residual effect of establishing pastures under a cover-crop in 2009 was poorer persistence and lower productivity by lucerne at the standard cover-cropping rate, and by phalaris, cocksfoot and chicory at all cover-crop rates, and an increased incidence of weeds. Similar responses to cover-cropping occurred between 2010 and 2012, even with the wetter establishment conditions in 2010, for phalaris, chicory and weeds, despite demonstration at Ariah Park that higher populations of individual perennial species could be achieved by doubling the sowing rate of pasture seed in 2010. Lucerne compensated for lower plant numbers by increasing herbage growth in response to rainfall, but phalaris could not and total pasture productivity over the first 2 years after establishment was greatly reduced by the use of cover-crops in both 2009 and 2010. Cover-cropping also reduced annual legume seedset, which could have implications for future pasture performance. Lucerne was the most consistently productive perennial pasture species evaluated regardless of establishment technique or climatic conditions.

Incorporation of perennial pastures into cropping rotations can improve whole-farm productivity, profitability and sustainability of mixed farming systems in southern Australia. However, success in establishing perennial pastures depends on choice of species, time of sowing, method of establishment, seasonal conditions, and whether sowing is under a cover-crop. Field experiments were sown from 2008 to 2010 to determine effects of sowing time and the presence of a cover-crop on the performance of four perennial pasture species, lucerne (Medicago sativa L.), chicory (Cichorium intybus L.), phalaris (Phalaris aquatica L.) and cocksfoot (Dactylis glomerata L.), at Yerong Creek, New South Wales (NSW). Results showed that lucerne was the most productive pasture, followed by chicory and phalaris, with cocksfoot being the poorest performer. Under favourable seasonal conditions, lucerne and chicory pastures produced 29.3 and 25.0 t ha^–1 of total dry matter (DM), comprising 71% and 52%, respectively, of sown perennial species in the sward in their second growing season, when sown in autumn. Spring-sown pastures produced 24.6 and 18.3 t ha^–1 of total DM in the second season, with 55% and 47% of sown species in the sward being lucerne and chicory, respectively. However, spring-sown pastures contained a very low proportion of subterranean clover (Trifolium subterraneum L.) in the sward in the first 2 years, despite efforts to broadcast seeds at the break of season in the following year. It is recommended that non-legume perennial species, such as chicory and phalaris, be sown in autumn with companion annual legumes until methods are developed and tested to establish annual legumes reliably in spring. However, lucerne can be established in autumn or spring because it can fix its own nitrogen and is not reliant on a companion legume. Cocksfoot cv. Kasbah, in general, appears less suitable than the other perennial species for this medium-rainfall environment in southern NSW. Our study showed that pastures sown without a cover-crop had the most reliable establishment, whereas pastures sown with a cover-crop in a dry year had poor establishment or total failure, as well as a significant reduction of grain yield from the cover-crop. In a wet year, pastures established satisfactorily under a cover-crop; however, growth of the cover-crop still suppressed pasture DM production in subsequent years. Research is under way to model our data to determine the likely financial implications of establishing perennial pastures under cover-crops.

In southern Australia, intercropping, pasture cropping and overcropping have evolved as techniques to address environmental problems such as dryland salinity and wind erosion and to utilise soil water outside the conventional winter-dominant growing season. We paired three winter-dormant pastures, including two subtropical C₄ perennial species (Rhodes grass, Chloris gayana; Gatton panic, Megathyrsus maximus) and the summer-active perennial C₃ legume siratro (Macroptilium atropurpureum), with a conventional barley (Hordeum vulgare)–lupin (Lupinus angustifolius) rotation to explore the extent to which different summer-active species reduced crop yields. We also examined whether the competition for resources could be altered by supplying increased nitrogen to the crop and changing the row spacing of the pasture.

Under high-input conditions, pasture reduced cereal crop yields by up to 26% and lupin yields by up to 29%. Under low-input conditions, pasture cropping did not significantly reduce crop yield, and frequently increased crop yields. With low inputs, barley yield increases in 2011 ranged from 23% to 31%. In lupins under low-input conditions, yield increases ranged from 91% to 106% in 2010 and from –6% to 39% in 2012. The impact of the crop on the pasture was less pronounced, where the timing of pasture growth was delayed by the crop, but absolute levels of production were not influenced by the crop. Row spacing altered the temporal dynamic of pasture production; initially, the pasture produced less than the narrow spaced equivalent, but after 2 years, production exceeded that in the narrow row. Across all pasture species in 2009 and 2012, winter pasture production reduced crop yield by 0.32 and 0.4 t grain/ha pasture biomass produced, implying that moderate yield losses occurred because pasture production was also moderate. In the other two years, winter pasture production did not affect crop yield, suggesting that the pasture was able to utilise resources surplus to crop requirements. In this environment, with this combination of crops and summer-active pastures, higher levels of inputs did not enhance crop yield in a pasture-cropping system. We suggest that grain yield losses are lower in the low-input system and this implies that, at some level, competition between the species was reduced in a nitrogen-limited environment and the extent of the competition depended on season.

Pasture cropping is a farming system in which annual crops are sown into established perennial pastures. It may provide environmental benefits such as increased groundcover and reduced deep drainage, while allowing traditional crop production in the Mediterranean-style climate of south-western Australia. In this research, we investigated deep drainage and the temporal patterns of water use by a subtropical perennial grass, annual crops, and a pasture-cropping system over a 4-year period. Both the pasture and pasture-cropped treatments reduced deep drainage significantly, by ∼50 mm compared with the crop treatment. Competition between the pasture and crop components altered patterns of average daily water use, the pasture-cropped treatment having the highest water use for July, August and September. Consequently, water-use efficiency for grain production was lower in the pasture-cropped plots. This was offset by pasture production, so that over a full 12-month period, water-use efficiency for biomass production was generally greater for the pasture-cropped plots than for either the pasture or crop monocultures. Pasture cropping may be a viable way of generating sustainable economic returns from both crop and pasture production on sandy soils of south-western Australia.

Pasture cropping is an emerging farming-systems practice of southern Australia, in which winter grain crops are sown into an established stand of a winter-dormant, summer-growing perennial pasture. There is a pressing need to define times, locations and climates that are suitable for pasture cropping. To evaluate effects of management interventions, agro-environment, and possible interactions on crop and pasture productivity associated with pasture cropping, an AusFarm^® simulation model was built to describe a pasture-cropping system based on annual crop and subtropical grass. The model was parameterised using data from field research on pasture cropping with barley cv. Buloke and a C₄ subtropical grass, Gatton panic (Panicum maximum cv. Gatton), conducted at Moora, Western Australia. The simulation was run over 50 years using the historical climate data of five southern Australian locations (Cunderdin, Jerdacuttup, Mingenew, and Moora in Western Australia, and Karoonda in South Australia). Two wheat cultivars and one barley crop were considered for each location, to examine the impact of crop phenology on this farming system.

Jerdacuttup and Moora favoured pasture cropping, with average barley-yield penalties of 10 and 12%. These locations were characterised by colder growing seasons, more plant-available water at anthesis, and more winter–spring rain. The cereal crops did not rely on stored soil moisture, growing instead on incident rain. The winter–spring growth of the Gatton panic pasture was highest at Mingenew. This generated a high yield penalty, 38% loss under pasture cropping, compared with the other locations. Changing the efficacy of a herbicide application to the pasture when the crop was sown had a strong effect on yield. Yield penalties at Moora and Mingenew reduced to 7 and 29%, respectively, when the proportion of live biomass killed by the herbicide was doubled.

Utilisation of soil moisture by the Gatton panic pasture during summer and early autumn had little effect on subsequent grain yield, whereas reduced pasture growth during the winter–spring growing period had a substantial effect on crop yield. Pasture cropping can therefore succeed in agro-climatic regions where crops can be grown on incident rain and pasture growth is suppressed through low temperature or herbicide. Perennial pasture growth should be minimised during the crop growing period through the management of crop sowing date, nitrogen fertiliser application and C₄ grass suppression to minimise the effect on stored soil water at crop anthesis.

In the Mallee region of southern Australia, the dry and variable climate results in frequent summer–autumn feed gaps, restricting the profitability of farms that combine livestock and crop enterprises. To assess the suitability of summer-growing perennial grasses to fill such feed gaps, two replicated field experiments comparing the persistence and productivity of several cultivars were conducted at Hopetoun and Karoonda. The data from these experiments also served to validate a C4 grass model, which was then used in a simulation experiment comparing productivity on two different soil types at three locations. Most grass cultivars established well except on sandy, non-wetting soils. At Hopetoun, four of five cultivars persisted over 6 years, demonstrating the tolerance of the selected cultivars to the typical long, dry summers and cold, wet winters of the region. Biomass production showed little difference between cultivars and a strong response to the amount of summer rainfall, ranging from 1500 to 3000 kg ha^–1 under average seasonal conditions and peaking at 9000 kg ha^–1 in the very wet summer of 2010–2011. Model performance was satisfactory (R² 0.85–0.93, RMSE 476–1673 kg ha^–1, depending on the cultivar), in terms of predicting both the magnitude and the timing of biomass production. Simulation outputs indicated that biomass production closely followed seasonal trends in temperature and moisture availability. Grazing potential was highest from early summer to autumn, which coincides with the period of feed shortages and highest marginal value of forage. In areas with warm-season (October–April) rainfall averages of 175 and 225 mm, the grazing of C4 grass pastures on marginal soils would be possible in at least 40% of the years for 2 and 3 months, respectively. It was concluded that summer-growing perennials are a promising option to alleviate feed gaps on mixed crop–livestock farms in areas with at least 150 mm of rainfall from October to April.

Non-symbiotic nitrogen (N₂) fixation by diazotrophic bacteria is a potential source for biological N inputs in non-leguminous crops and pastures. Perennial grasses generally add larger quantities of above- and belowground plant residues to soil, and so can support higher levels of soil biological activity than annual crops. In this study, the hypothesis is tested that summer-active perennial grasses can provide suitable microsites with the required carbon supply for N₂ fixation by diazotrophs, in particular during summer, through their rhizosphere contribution. In a field experiment on a Calcarosol at Karoonda, South Australia, during summer 2011, we measured populations of N₂-fixing bacteria by nifH-PCR quantification and the amount of ¹⁵N₂ fixed in the rhizosphere and roots of summer-active perennial grasses. Diazotrophic N₂ fixation estimates for the grass roots ranged between 0.92 and 2.35 mg ¹⁵N kg^–1 root day^–1. Potential rates of N₂ fixation for the rhizosphere soils were 0.84–1.4 mg ¹⁵N kg^–1 soil day^–1 whereas the amount of N₂ fixation in the bulk soil was 0.1–0.58 mg ¹⁵N kg^–1 soil day^–1. Populations of diazotrophic bacteria in the grass rhizosphere soils (2.45 × 10⁶ nifH gene copies g^–1 soil) were similar to populations in the roots (2.20 × 10⁶ nifH gene copies g^–1 roots) but the diversity of diazotrophic bacteria was significantly higher in the rhizosphere than the roots. Different grass species promoted the abundance of specific members of the nifH community, suggesting a plant-based selection from the rhizosphere microbial community. The results show that rhizosphere and root environments of summer-active perennial grasses support significant amounts of non-symbiotic N₂ fixation during summer compared with cropping soils, thus contributing to biological N inputs into the soil N cycle. Some pasture species also maintained N₂ fixation in October (spring), when the grasses were dormant, similar to that found in soils under a cereal crop. Surface soils in the rainfed cropping regions of southern Australia are generally low in soil organic matter and thus have lower N-supply capacity. The greater volume of rhizosphere soil under perennial grasses and carbon inputs belowground can potentially change the balance between N immobilisation and mineralisation processes in the surface soils in favour of immobilisation, which in turn contributes to reduced N losses from leaching.

Plantings of forage shrubs such as saltbush (Atriplex spp.) in the drier part of the crop–livestock zone of southern Australia have the potential to help fill feed autumn gaps, provide valuable feed during drought periods, and provide year-round groundcover, shelter for livestock and options for management of saline soils. However, the proportion of farms with forage shrub plantings and the extent of those plantings remain relatively low, with the rate of new plantings slowing over the past decade. Development of new forage-shrub options has been occurring with the aim of improving the feed value and adoption of forage shrubs. Using a whole-farm bio-economic optimisation model for a crop–livestock farming system in the low-rainfall Mallee region of southern Australia (Mallee MIDAS—model of an integrated dryland agricultural system), we explored how key attributes of forage-shrub plantings and the associated pasture understorey, such as biomass growth, digestibility and ease of establishment, can make forage shrub plantings economically more attractive to farmers. We found that saltbush types and forage-shrub options with improved feed quality characteristics will offer the opportunity for improved economic returns and increased profitability from larger plantings compared with existing options. Improving feed quality was more important than increasing the growth rates of saltbush plants. Results still indicate only a niche role in farming systems, with profit typically being greatest when using relatively small areas (<10% of farm area) on the less productive soils of the farm. The results suggest that the profitability of forage shrubs will be greatest for those growers with larger areas of marginal cropping soils and greater reliance on livestock than cropping. Furthermore, the results demonstrate that, if cereal prices or yields fall significantly and/or lamb prices rise, the value of a forage shrub planting can increase substantially. The principles revealed have wide application beyond the region, although these need to be adapted on-farm and widely disseminated before potential contribution to Australian agriculture can be realised.

Old man saltbush (Atriplex nummularia Lindl.) is a useful forage shrub for livestock in the low-rainfall areas of the world, and particularly in Australia. In these semi-arid and arid environments, saltbush is valuable for increasing the production from otherwise marginal areas of the farm and during drought periods when there are few feed alternatives. The ability to predict the growth and development of perennial forages such as old man saltbush in response to rainfall, soils and farm management is necessary for farming system planning and design purposes. A field experiment was conducted at Waikerie, South Australia, to inform the development of a new forage shrub model for use in the APSIM framework. The model takes into account the common setup of saltbush plantations in alley systems, by simulating light interception and water uptake for interacting shrub and inter-row zones separately. This is done by modelling the canopy and root system development. Field data across three soil types along a landscape catena showed that the model was able to satisfactorily predict daily biomass accumulation, partitioning into leaf and woody biomass, and regrowth after grazing. The model was sensitive to properties associated with the root system, and with limited parameterisation can be tailored to simulate different clonal cultivars. The model can now be used in the APSIM framework to assess temporal and spatial dynamics of forage systems combining shrubs with herbaceous pasture components.

Addressing the opportunities and challenges for integrating perennial forages and shrubs into the mixed crop–livestock farming systems of southern Australia has been the focus of the Future Farm Industries Cooperative Research Centre EverCrop project. This overview discusses the use of perennial plants in cropping landscapes in terms of the concepts of ‘rotation, separation and integration’ and highlights the contribution of papers in this special issue of Crop and Pasture Science across a range of biophysical and socioeconomic factors. Drivers for the inclusion of perennial forage plants include salinity management, groundcover maintenance and filling seasonal feed gaps, and this need will continue as mixed crop–livestock systems evolve in the context of managing business risk and a requirement for better natural resource management outcomes.