The Role of Forages in Sustainable Cropping Systems of Southern Australia

The historical context, recent trends, and possible future role of forages in cropping systems are reviewed. Three recent themes will be developed: 1) The successful exploitation of genetic diversity resulting in commercial development of new legume species as pasture cultivars with specific traits better suited to the needs of current farming systems. 2) Improved understanding of key soil processes under grazed pastures, particularly soil water and soil nitrogen, and how these processes impact on indicators of sustainability like deep drainage and nitrate leaching. 3) An emerging capacity for predicting the effect of pasture-crop sequences on soil processes, crop growth and grain yield. In response to changing economic pressures and threats to sustainability, new farming systems involving forages are continually evolving. Increasing cropping intensity has placed pressure on pasture-crop systems that rely on self-regeneration of annual legumes following crops. One response has been the emergence of phase cropping systems, where a sequence of pasture years is followed by a sequence of cropping years. Another response has been an expansion in the area of lucerne grown in rotation with crops. In the future, forages in cropping systems will continue to fulfil the traditional roles of diversifying farm income through livestock production and supporting the cropping enterprise through maintenance of soil fertility. But increasingly, forages will be utilised to maintain the sustainability of agricultural production systems. Examples include competitive forages as a component of integrated weed management and high water use forages for reducing recharge and the associated spread of dryland salinity

Evaluation with Simulation of Lucerne-Based Cropping Systems to Combat Dryland Salinity in Australia

Dryland salinity is one of the most significant forms of land degradation that farmers face in Australia. There are currently 2.5 million ha affected by dryland salinity in Australia, and this may rise to 15 million ha over the next 30 to 100 years if no action is taken. National field experiments suggest that adoption of cropping systems that integrate deep-rooted perennials, such as lucerne, are important to reduce dryland salinity. This paper reports simulation results with APSIM (The Agricultural Production Systems Simulator), that have been used to explore climate, soil and agronomic factors affecting effectiveness of lucerne-based phase and companion cropping systems in sustaining crop yield and reducing deep-water drainage in South Australia

Evolution of Integrated Crop-Livestock Production Systems

Many factors contribute to changes in the crop-livestock systems, but no logical end-point in the evolution process exists. While benefits of integrated crop-livestock systems over specialised crop and livestock systems are well documented, there has been a move to specialised crop and livestock production. Sustainability issues (manure nutrient concentration, soil quality maintenance, salinity, herbicide resistance, economic instability) have created a renewed interest in integrated crop-livestock systems. Farmer adaptability is as an important link in the evolution between ‘states of integration’

Evolution of Integrated Crop-Livestock Production Systems

Key points 1. Many factors contribute to changes in the crop-livestock systems, but no logical end-point in the evolution process exists. 2. While benefits of integrated crop-livestock systems over specialised crop and livestock systems are well documented, there has been a move to specialised crop and livestock production. 3. Sustainability issues (manure nutrient concentration, soil quality maintenance, salinity, herbicide resistance, economic instability) have created a renewed interest in integrated crop-livestock systems. 4. Farmer adaptability is as an important link in the evolution between ‘states of integration’

How we used APSIM to simulate conservation agriculture practices in the rice-wheat system of the Eastern Gangetic Plains

Examples of how to simulate performance of conservation agriculture (CA) and conventional tillage (CT) practices using cropping systems models are rare in the literature, and from the Eastern Gangetic Plains (EGP). Here we report a comprehensive evaluation of the capacity of APSIM for simulating the performance of CA and CT cropping practices under a diverse range of tillage (CT vs zero tillage (ZT)), crop establishment options (puddled transplanted rice vs unpuddled transplanted rice), residue, N rates, and irrigation practices from two sites in the EGP that differed in soil type, water table dynamics, and agro-climatic conditions. We followed a robust procedure of model parameterisation, calibration, and validation, then undertook statistical analyses to evaluate model performance. We have demonstrated that when different values for key model input parameters are employed (i.e. change in soil properties (Ks, BD)), crop rooting parameters (xf- root hospitality, kl- root extraction efficiency) and soil microorganism activity (Fbiom- fraction of soil organic matter present as microbial biomass and Finert- the inert fraction of soil organic matter), the model performed well in simulating the different performances of CA and CT management practices across the environments in the EGP. Model performance was markedly better in the full-N than in zero-N, but both are still considered acceptable. In addition to well-watered and fertilised treatments, the model was able to capture an observed crop failure in rainfed unpuddled transplanted rice accurately, illustrating an ability to capture crop response under a wide range of water stress environments. As demonstrated by robust statistical criteria, APSIM was able to capture the effect of cropping system, irrigation, tillage, residue, and N-application rate within the bounds of experimental uncertainty, hence is now deemed a suitable tool for scenario analyses around the relevant practices

Latest results from the Pamela experiment

In this paper we present the latest results of the Pamela satellite experiment, focusing in particular on the p/p and the e +/(e+ +e-) ratios

Improving the productivity and sustainability of rainfed farming systems for the Loess Plateau of Gansu Province

The climate, soils and farming systems from Dingxi and Xifeng, two regional centers of eastern Gansu Province are described. Farm size is small (1 ha) and farm income is low ($A330 per person and year). Farmers grow a mixture of crops and livestock for subsistence and cash income. A feature of the environment is highly variable rainfall and an agricultural system that relies on stored soil water from the summer rain season (July to September) for use by crops and forages in the following spring. Research evaluating conservation tillage under local conditions has produced encouraging results with grain yields from an experimental no-tillage stubble retained treatment equal to or greater than grain yields from a conventional tillage and stubble removed treatment across a range of crops and seasons. This research will move from a “proof of concept” phase to an “on-farm research” phase where the focus will be on how farmers adapt conservation tillage to local conditions. The implications of integrating lucerne (Medicago sativa) into cereal cropping systems for soil water dynamics, soil nitrogen, and productivity of lucerne and wheat were also studied. Lucerne is highly productive in this environment and can minimize water “losses” through runoff and drainage. Productive lucerne / wheat rotations can be developed but the transition from the perennial forage to the annual crop needs to be managed carefully to avoid risks associated with dry soil and/or low soil inorganic nitrogen. The combination of field experimentation to create comprehensive databases, with simulation modeling, and on-farm research, has significantly contributed to a better understanding of the constraints and opportunities in these farming systems. Future research will focus on farmer adaptation of conservation tillage and integration of forages and crop residues for livestock production

Farmers value on-farm ecosystem services as important, but what are the impediments to participation in PES schemes?

Optimal participation in market-based instruments such as PES (payment for ecosystem services) schemes is a necessary precondition for achieving large scale cost-effective conservation goals from agricultural landscapes. However farmers' willingness to participate in voluntary conservation programmes is influenced by psychological, financial and social factors and these need to be assessed on a case-by-case basis. In this research farmers' values towards on-farm ecosystem services, motivations and perceived impediments to participation in conservation programmes are identified in two local land services regions in Australia using surveys. Results indicated that irrespective of demographics such as age, gender, years farmed, area owned and annual gross farm income, farmers valued ecosystem services important for future sustainability. Non-financial motivations had significant associations with farmer's perceptions regarding attitudes and values towards the environment and participation in conservation-related programmes. Farmer factors such as lack of awareness and unavailability of adequate information were correlated with non-participation in conservation-based programmes. In the current political context, government uncertainty regarding schemes especially around carbon sequestration and reduction was the most frequently cited impediment that could deter participation. Future research that explores willingness of farmers towards participation in various types of PES programmes developed around carbon reduction, water quality provision and biodiversity conservation, and, duration of the contract and payment levels that are attractive to the farmers will provide insights for developing farmer-friendly PES schemes in the regio

Supplementary feeding with grain improves the performance of sheep grazing saltbush (Atriplex nummularia) in autumn

Merino wethers aged 1.5 years grazed a saltland pasture comprising old man saltbush (Atriplex nummularia) with an inter-row of senesced grasses and medic for 6 weeks in autumn, in a cereal–livestock zone with a Mediterranean-type environment in South Australia. The experimental treatments were a control (old man saltbush, SB), supplementation with 250 g/sheep.day barley straw (SB + S), supplementation with 250 g/sheep.day barley grain (SB + G) and supplementation with 250 g/sheep.day barley straw + 250 g/sheep.day barley grain (SB + S + G). The sheep in SB + G finished the experimental period significantly heavier (53.6 kg, P < 0.001) than SB (51.0 kg), SB + S (50.5 kg) or SB + S + G (51.1 kg) animals. Feeding grain also increased length of wool grown daily by 16% and would have increased the value of the sheep by being able to sell them ‘out of season’ when prices are higher. Sheep supplemented with grain alone had a higher liveweight than those provided with grain and straw, a result that cannot be explained but may be associated with altered grazing behaviour. It appears that, while old man saltbush provides sheep with an acceptable intake of protein and minerals, the addition of a cereal grain supplement improves energy balance and optimises rumen protein capture to improve liveweight and wool growth performance