2019 has seen FFN partner with Charles Sturt University to provide FFN members with access to a series of the University’s studies directly relevant to young farmers. This first study analyses the value of hard-seeded annual legumes in mixed farming operations. Please contact CSU or FFN should you wish to find out more.
The value of hard-seeded annual legumes in mixed farming systems has been examined by researchers from the Graham Centre for Agricultural Innovation and these drought-tolerant pastures are already making a big difference to one Riverina farmer.
Seven years of research at the Centre, an alliance between Charles Sturt University (CSU) and the NSW Department of Primary Industries (DPI), has included hard-seeded annual legumes like biserrula, arrowleaf clover, French serradella, bladder clover and gland clover.
NSW DPI soil research officer, Dr Belinda Hackney said biserrula has proved to be incredibly tough, particularly in below average rainfall years where its deep root system allows production of more forage and seed than traditional shallow-rooted annual legumes that often struggle to survive under these conditions.
“Biserrula has very high levels of hard seed and persists in the seed bank enabling it to survive a number of cropping years and regenerate on-demand without the need for re-sowing,” Dr Hackney said.
“Biserrula can be used as part of an integrated weed control strategy to help control problem cropping weeds such as annual ryegrass. It has lower palatability than annual ryegrass and sheep selectively remove it from the sward helping to reduce reliance on herbicides.
- Biserrula is very drought tolerant – in 2018 on 90 mm growing season rainfall, biserrula produced more than 170 kg seed/ha compared to sub clover and annual medic that produced less than 10 kg/ha.
- Biserrula establishes readily on well drained soils of mild to moderate acidity. It is not suited to use on heavy textured, high clay content soils that may be subject to waterlogging
- Biserrula has established well using summer, strategic dry and conventional stand-alone sowing options.
- Under very dry summer conditions, summer sowing may be less effective due to slow rate of hard seed breakdown.
Proving its worth on-farm
Hard-seeded annual legumes have become a key part of the rotation on Mike O’Hare’s mixed farming enterprise at Beckom in the NSW Riverina.
About half the farm (900ha) has been planted to biserrula with the remainder a mix of bladder, gland and arrowleaf clovers
Mr O’Hare said “Not only is biserrula able to survive we get a false autumn break but it performs at the other end of the season too, hanging on for an extra grazing at the end. If we get late rain on a clover paddock you’ll see weeds but the biserrula out competes them, providing feed not weeds.”
Mr O’Hare said the goal is to establish the pasture in the first year to maximise seed set, the second year provides an opportunity for heavy grazing before spraying out in spring to provide a fallow break for Canola to be sown in year three. Year four will see wheat planted and then the biserrula regenerates after the cropping phase of the rotation.
The next step for research
New research, funded by the Grains Research and Development Corporation (GRDC)* is investigating the role of hard-seeded legumes used as on-demand pasture breaks in cropping rotations.
Dr Hackney says the research includes species completely new to Australian agriculture as well as those mentioned in this article and is focusing on their ability to supply biologically fixed nitrogen and reduce reliance (and associated input costs) on fertiliser nitrogen.
- Choose a legume suited to your soil type, rainfall, intended use and management needs.
- Weed control prior to sowing is key to success in pasture establishment.
- Don’t compromise on sowing rate. Use an appropriate rhizobia delivery mechanism matched to sowing time and soil moisture conditions.
- Biserrula can cause primary photosensitisation in grazing animals –see this Factsheet for more information. Understanding photosensitisation in sheep grazing biserrula pastures
*This project is supported by funding from the Australian Government Department of Agriculture and Water Resources (as part of its Rural R&D for Profit program), the GRDC, Meat and Livestock Australia (MLA) and Australian Wool Innovation (AWI). The research partners include the South Australian Research and Development Institute (SARDI), Murdoch University, CSIRO, the WA Department of Primary Industries and Regional Development (DPIRD), and Charles Sturt University (CSU), as well as grower groups
Dr Belinda Hackney | Research Officer, Soils
NSW Department of Primary Industries
Photo: Mike O’Hare in a paddock of biserrula during greener times. Photo by Ted Wolfe