Although growers in high-rainfall areas are often concerned about their over-reliance on canola as a break crop, a new GRDC-supported study suggests one way to increase the adoption of alternatives and diversity of crop options is to build grower confidence in crops other than cereals and canola.
The push is on to increase the reliability and performance of legumes in rotations, in areas to which they are suited.
PHOTO: Paul Jones
In 2014-15, Helen Burns and Dr Mark Norton, of the NSW Department of Primary Industries, surveyed 221 high-rainfall growers from southern NSW, north-east Victoria, south-east South Australia, south-west Tasmania and Victoria’s Gippsland region.
The researchers were keen to understand the constraints to legume plantings. They also ran focus groups and interviewed growers to explore the issues in further detail.
Ms Burns says that as canola markets and growers’ confidence increased, canola had replaced lupins as the break crop of choice on better-drained soils in most of the high-rainfall zone (HRZ).
“The survey showed that while Lupinus angustifolius is grown in all areas of the HRZ, L. albus plantings are confined to well-drained soils of the NSW slopes,” she says.
“Lupins are considered a low-maintenance, low-input crop that can be ‘sown and forgotten’, and as a consequence it is the dominant pulse in the NSW–Victorian Slopes region where many growers are sowing it with little or no fertiliser.”
Ms Burns says faba beans are the best adapted of the pulse crops to soils prone to waterlogging and is the pulse of choice in SA, south-west Victoria and Victoria’s Gippsland region. Despite having a relatively high management requirement, she says the area sown to faba bean is predicted to increase as growers and advisers gain more experience and confidence.
Prompted by reports of high yields and grain prices, and lack of adviser experience, the survey showed growers were doing their own research on faba beans and trialling small areas (30 to 100 hectares) to develop experience and confidence.
Ms Burns says legume species are rarely sown as brown or green manure crops on the high-value farming country of the HRZ.
“Most growers are reluctant to forgo a year of income and therefore ‘manuring’ is likely to be a last resort option when there is an unexpected ‘blow-out’ of herbicide-resistant weeds, most commonly annual ryegrass,” she says.
“Manure crops are often low input and sown with minimal fertiliser or weed management, which is likely to compromise legume dry matter production and nitrogen fixation. A hay or silage cut, which provides a potential income source, was the preferred option to prevent weed seed-set.”
When it came to pastures, Ms Burns says advisers from Victoria, SA and Tasmania interviewed for the study were concerned about the quality of pastures.
She says the advisers interviewed thought the sub-optimal performance of pasture legumes was caused by minimal investments in fertiliser and pasture improvement, poor species and/or variety selection and poor understanding by some growers and advisers of basic pasture management.
The advisers interviewed also noted that many growers viewed the pasture phase as a “fix-all”, an opportunity to start the cropping phase “with a clean slate”. However, she says that these advisers considered weed management, legume content and growth in these pastures was sub-optimal and nitrogen fixation was likely to be low.
To better understand the factors likely to influence a decision to include legume crops and pastures in crop sequences, the survey asked growers to rate the importance of a list of factors (Table 1).
The growers surveyed were also asked to indicate what information and technologies they required to increase the use of legumes in their cropping sequences (Table 2).
Ms Burns says the study showed weed management, estimates of break-even crop yield and simple gross margin calculations are the main factors that drive the crop sequence decisions of most growers.
“Most growers do not place an economic value on the additional rotational benefits of pulse crops such as added nitrogen or disease and weed management, and consider that every crop must be profitable in its own right,” she says.
“There is considerable information available that can be applied to the HRZ to improve legume adoption through, for example, weed seedbank management, effective nodulation of legume species and legume nutrition.”
She says financial studies comparing crop sequences and the integration of crop and livestock enterprises needed to provide long-term ‘whole-of-system’ analyses that separate the financial return for each enterprise and the system.
There is also a need to quantify the risk and consequences of crop sequence decisions, particularly with regard to management of herbicide resistance and disease, she says.
Table 1 Factors that may influence growers' decisions to include legume crops and pastures in their cropping sequences
| Factors that may influence crop sequence decisions
|Rating average (out of 5)
|Increased weed management options (within the legume crop)
|| 1 (89%)
| Financial return of crop and system
|| 2 (87%)
|Disease management (increased diversity of crops increases weed and disease management opportunities)
|| 3 (70%)
|Diversity of income sources
|| 4 (63%)
|Cost of nitrogen fertiliser
|| 5 (52%)
|Ability to manage seasonal variability
|| 6 (44%)
|| 7 (41%)
|| 8 (27%)
Table 2 The information and technology required to increase confidence in the use of legumes in crop sequences.
|Information and technology gaps
|Rating average (out of 5)
| Weed management and herbicide options
| Legume crop and pasture options adapted to soil and climate
| Improved features of existing varieties, for example, disease resistance
| Quantification of financial benefits of legume crops and pastures
| Disease management
| Specific agronomy packages for specific legume species
| Stability of markets
| Improved inoculation (nodulation) of legume species
| Integrated pest management
| Trace element requirements of legumes
| Infrastructure and grain delivery options
* The percentage of respondents who considered the factors presented as either ‘very important’
or ‘important’ is shown in brackets.
SOURCE: NSW DPI
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