The challenge

Mixed farming systems provide valuable ways to mitigate production risks in low and medium-rainfall zones. Besides returns from stock, the benefits of legume pastures in rotations have been shown to boost average farm profit and reduce risk of financial losses compared to intensively cropped farms.

To fully exploit these benefits, however, a need was identified to discover and commercialise new and better-adapted legume pasture species.

Among the desired new features was an enhanced capacity to cope with variable climatic conditions and improved flexibility when moving between crop and pasture phases. This translates into legumes that reliably establish and produce hard seed that persists through a cropping phase. This allows the pasture to readily regenerate when needed and supply quality feed to livestock and fix nitrogen for crops.

Legumes matching these criteria in mixed farming systems in Australia were found to be low compared to traditional annual legumes, such as subterranean clover and annual medics.

However, with the seedbank of traditional legumes declining – and growers unwilling to resow them due to cost and poor performance – the need for new, better-performing legume pastures became urgent.

The response

From 2017 to 2022, GRDC invested in a suite of projects under the Dryland Legume Pasture Systems (DLPS) initiative. Its aim was to commercialise new legume pastures and support their adoption through innovative management methods.

Project activity was undertaken in southern New South Wales, Victoria, South Australia and Western Australia by multidisciplinary research teams that included soil, crop and pasture scientists interacting with agricultural economists and extension officers.

DLPS was structured into four programs of research and development that sought to acquire an understanding of:

• pasture species adaptation and the limits of where they can be successfully grown;
• the range of benefits pasture species provide to cropping and livestock enterprises;
• how different legume species affect farm profit and risk;
• how pastures can be more cost-effectively and efficiently established; and
• how to increase growers’ knowledge and experience of pastures.

A strong project focus was on hard-seeded species that regenerate from a bank of seed in the soil. Characteristics associated with hard seed breakdown mean that growers can then choose in which season the legume pasture is allowed to regenerate, which in turn allows for variable sequences of cropping that best mitigate risks from variable growing conditions.

The DLPS was undertaken as a collaboration between the South Australian Research and Development Institute, Murdoch University, CSIRO, the WA Department of Primary Industries and Regional Development, NSW Department of Primary Industries and Charles Sturt University.

Grower groups were also integral to the operations of the DLPS. Included were Mingenew-Irwin Group, Corrigin Farm Improvement Group, ASHEEP Esperance, Agricultural Innovation and Research Eyre Peninsula, Upper North Farming Systems, Mallee Sustainable Farming, Birchip Cropping Group and Central West Farming Systems.

It received additional funding from the Australian Government Department of Agriculture, Water and the Environment as part of its Rural R&D for Profit program, GRDC, Meat & Livestock Australia and Australian Wool Innovation.

The impact

Research work undertaken through the DLPS successfully developed and promoted low-cost legume pasture options. Included among the commercialised species are:

• Frano serradella;
• Yellow serradella;
• bladder clover;
• Trigonella balansae; and
• Seraph medic.

Combined with reliable establishment techniques and management packages, these pasture systems were shown to benefit both crops and livestock production on a range of soil types.

Furthermore, most of the novel legumes have hard-seeded features and are aerial seeders, enabling them to be easily harvested and multiplied on-farm at low cost. Summer sowing of legumes further enables hard seed breakdown and exploitation of early breaks to the season in many areas.

Among the lasting benefits identified are:

• increased flexibility in decision-making;
• increased nitrogen fixation in the farming system;
• higher grain protein content in cereals; and
• highly nutritional forage that boosts livestock productivity with the potential to reduce methane emissions for meat and wool production systems.

A cost-benefit analysis of benefits was undertaken using whole-farm economic models. In WA, the whole-farm results showed a potential increase in farm profits of $16 per hectare per year. In eastern parts of Australia, the increase was estimated at $46/ha/year.

An aggregate potential increase in farm-level benefit is estimated to be $31 million per year over one million hectares of both regions.

When compared to typical baseline or existing farm returns from crop-pasture sequences, the implementation of new DLPS technologies was estimated to increase farm-level profits by 24 per cent in WA and 33 per cent in eastern Australia.

The net present value of investment in DLPS has been estimated at $57 million, resulting in a benefit cost ratio of 4.3:1. The internal rate of return and the modified internal rate of return are 20 per cent and 10 per cent respectively. Sensitivity analysis found that these overall results are quite robust to changes in some of the key parameters.

The economic analysis was performed by Bob Farquharson & Associates.

More information: view the Delivering impact case studies.