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Grazing-system experiments address complex interactions among animals, pastures, soils, climate and management. As part of the national EverGraze program, a grazing-system experiment was designed to determine how the intensity of grazing management, from continuous grazing (P01) to flexible 4- and 20-paddock rotational systems (P04 and P20), influences the profitability and sustainability of a Merino ewe, terminal sire, lamb production system grazed on heterogeneous native pastures. When implementing such an experiment, it is important to understand and characterise landscape variability, and include this in the design of the experiment. A second challenge for grazing-system research is to operate experimental systems with sufficient flexibility to adequately represent commercial production systems and maintain even utilisation across treatments. The present paper addresses the following two issues: (1) the process used to characterise the potential productivity of variable native pastures and the results of this characterisation; and (2) the development of flexible systems that adequately represent commercial production within an experiment. This was undertaken with input from a project-steering committee called the EverGraze Regional Group, comprising producers, extension staff and private consultants. Prior to the commencement, the site was mapped into three production zones, namely, high (HPZ), medium (MPZ) and low (LPZ), by visually estimating green herbage mass in late spring and marking boundaries between zones with a GPS. The production zones represented differences in soil properties (gravel, pH and available P) and pasture composition, and were used to balance potential production among plots within the same replication. Grazing-system options were evaluated using the sustainable grazing systems pasture model to help choose an appropriate starting stocking rate. The initial stocking rate chosen for the spring-lambing systems was 5.4 ewes/ha. The modelling predicted large variations in feed availability and quality over summer among years; flexible management criteria were therefore developed, including variable sale time for lambs, to utilise the greater feed supply in better seasons. Minimum-pasture benchmarks (>0.8 t DM/ha standing herbage mass and >80% ground cover) and variable green herbage-mass targets were designed to sustain high levels of livestock production and prevent pasture degradation. Criteria for adjusting ewe numbers were developed, but were constrained to pre-joining (March), scanning (July) and post-weaning (December), being consistent with commercial practices. The experiment incorporated flexible management rules as these were considered integral to the successful management of commercial grazing systems.

Native pastures account for approximately half the grazing area of the high-rainfall zone of southern Australia and the appropriate intensity of grazing management to improve pasture production and to sustain native species composition is still debated. This paper describes differences in pasture herbage mass, ground cover and composition for a native pasture managed under three distinct grazing-management intensities (1-, 4- and 20-paddock grazing systems). Grazing-management treatments were implemented for 4 years across a variable landscape and the interaction of grazing management and landscape position (high-, medium- and low-production zones) were examined. Increasing the intensity of grazing management (number of paddocks in the grazing system) resulted in higher standing, green and litter herbage mass and ground cover of pastures, with differences most pronounced in the high-production zone where selective grazing was regulated with grazing management. Landscape position largely influenced pasture composition, with higher pasture production and more productive species (e.g. Microlaena stipoides, Lolium rigidum and legumes) in the high-production zone. Small increases in the DM of native perennial grasses and lower levels of legumes and broad-leaf weeds developed in the 20-paddock system compared with grazing in 1- and 4-paddock systems. Net pasture growth was higher in the 20-paddock than 1-paddock treatment during spring in the last 2 years of the experiment, resulting in 21% (1.6 t DM/ha) more herbage mass accumulated over the year. While productivity and cover were higher under intensive rotational grazing, grazing management had little influence on pasture composition. A stable perennial pasture (>70% perennial grasses) stocking rates that were not degrading and the strong influence of landscape on pasture composition limited management influences. Practically, the results indicated that, at the same stocking rate, increasing the intensity of grazing management can increase the average pasture herbage mass, ground cover and pasture growth by more evenly distributing grazing.

Assessments of grazing systems are often constrained by the decisions regarding the management of the grazing systems, including stocking rate, and also the seasonal conditions that occur during the assessment period. These constraints have led to sometimes conflicting results about comparisons of grazing management systems. This paper examines 1-, 4- and 20-paddock (1P, 4P and 20P) grazing management systems to determine how the intensity of grazing management on native pastures influences the financial performance of sheep production systems. The performance of the grazing systems, as part of the Orange EverGraze research experiment, was initially examined using the biophysical data over the 4 years of the experiment and then a more detailed analysis over a longer timeframe was undertaken using the AusFarm simulation modelling software. Flexible management strategies to optimise ewe numbers, sale time of lambs, and adjust ewe numbers based on season, were also assessed to determine which management systems are the most profitable and sustainable. There was higher profit for the 20P grazing system than the 1P system during the experiment. However, when stocking rates were held constant at optimum levels and systems were simulated over 40 years, there was no difference between grazing systems. Modelling strategies used to vary stocking rates showed that flexible management options are better based on optimising ewe numbers and the sale time of lambs rather than changing ewe numbers between years. The sustainability of modelled systems was also assessed using frequency of events where the average herbage mass (0.8 t DM/ha) or ground cover (80%) in autumn dropped below levels that are associated with degradation. Degradation events occurred more so with increasing ewe number than lamb sale time. Overall, the most sustainable systems, when considering profitability and environmental issues, had a stocking rate of 4.2 ewes per ha, with lambs sold in February (2 or 18). Higher stocking rates (5.3 ewes/ha) would need to be run for more intensive grazing management to have higher profitability.

The Grain & Graze Whole-Farm Model was developed as a simple modelling tool to identify better strategies to improve the income of farmers and overcome grassland degradation. Using information on farm structure, crop and forage production systems, livestock production systems and variable costs involved in all enterprises, maximum whole-farm gross margins are obtained for an optimum or a prescribed mix of enterprises. The incorporation of production systems for different rainfall scenarios enables climatic risks and water use efficiencies of different enterprises to be investigated. Model simulations demonstrated the potential improvements that could be achieved in dollar water use efficiency ($WUE), by changes in management and/or changes in enterprise. The design of the model makes it a valuable tool for evaluating new systems, as it easy to develop new crop, pasture and livestock systems. Innovative farming systems such as pasture cropping and alley farming are included in the model.

Pasture cropping is a farmer-initiated concept of sowing a winter active cereal into a summer-active native perennial pasture. Proponents claim that by using pasture cropping they are able to maintain or improve the perennial pasture. Research was carried out on a Bothriochloa macra dominant pasture at Wellington, in the central western slopes of New South Wales, to compare pasture cropping to conventional no-till cropping and pasture only systems under different fertiliser rates and rotations. Key variables for the comparison included forage and crop production, pasture perenniality and ground cover, soil fertility and water use, and profitability. Our results show that pasture cropping can successfully retain perennial grasses and ground cover while still producing profitable cropping and grazing compared with continuous pasture. Crop yields from pasture cropping were less than 65% of those for conventional no-till cropping, which led to conventional no-till cropping having the greatest, but also most volatile, gross margin throughout the experiment. However, the lower input costs associated with pasture cropping reduced the effects of crop failure on farm profit. While soil moisture differences did not occur between treatments during the experiment, soil fertility, especially N, played a major role in determining crop yield. The role of pasture cropping in farming systems is discussed.

Soil water, runoff amount and quality, pasture production and environmental data were measured for a pastoral prime lamb enterprise in the Central Tablelands of New South Wales from 1998 to 2002. There were 4 pasture treatments: fertilised and sown chicory (CH), fertilised and sown introduced pastures (SP), fertilised naturalised pastures (FN) and unfertilised naturalised pastures (UN). Two grazing management regimes, tactically grazed (TG) and continuously grazed (CG) were imposed on the SP, FN and UN treatments. The CH treatment was rotationally grazed. To compare pasture and grazing system water use, maximum soil water deficit values (SWDMax) were calculated from neutron moisture meter data. SWDMax was influenced by both environmental and management factors. Management factors that influenced SWDMax were herbage mass of perennials, degree of perenniality, and the perennial species present. Environmental factors accounted for >50% of the variation in SWDMax. Inclusion of management factors (perennial herbage mass of C3 and C4 species and percentage perennial herbage mass), accounted for an additional 16% of variation. While the influence of pasture management appears to be relatively small, importantly, management is the only avenue available to land managers for influencing SWDMax. The UNTG and all sown treatments, with greater perennial herbage mass or greater C4 herbage mass consistently produced the highest SWDMax. Runoff amount and quality data are presented for ground cover percentages which generally exceeded 80% for the experimental period. Runoff as a proportion of rain received during the experiment was

Declining grassland productivity is a major concern in southern temperate Australia. Continuous grazing is thought to be a primary contributor to this decline, which is associated with the loss of perennial grasses. Landholders are evaluating grazing management strategies that might curb the loss of perennials and increase long-term productivity. This study reports on a comparison between continuous grazing and time-control grazing with sheep and cattle using a paired-paddock design at 5 locations in south-eastern Australia (lat. 30–42°S) over 6 years (1994–99). Pasture herbage mass, grassland species composition and basal cover of perennial grasses were assessed at 6-monthly intervals. Species abundance data were analysed by ANOVA, ordination (multi-dimensional scaling) and splining procedures to assess comparative trends between the 2 management treatments at each site. Species were categorised into major functional groups for analysis. Over all 5 sites there were few consistent differences between management treatments (continuous grazing v. time-control grazing). Basal cover was greater on the time-control grazing management compared with continuous grazing for most of the experimental period at 3 sites, but the initial values were also greater, resulting in a non-significant management × time interaction. Based on this study, we conclude that there was no apparent medium-term benefit of a multi-paddock rotational (time-control grazing) grazing system over continuous grazing for encouraging and maintaining a favourable botanical composition. The benefits for land managers from employing systems such as time-control grazing may accrue through other mechanisms. The study also highlights some of the difficulties with conducting on-farm paired-paddock research.