The value of vetch in cropping rotations is now widely recognised by Mallee farmers, motivating research into how this versatile crop can bring increased benefits to cropping systems.
At BCG’s 2015 main site at Berriwillock, a vetch varieties trial has been established, the aim being to examine how new varieties perform in the Mallee environment.
The field trial, which is being carried out on behalf of the South Australian Research and Development Institute (SARDI), will include 12 vetch varieties including a number of experimental lines.
As well as measuring how each variety grows and yields, researchers will be looking to identify each lines level or resistance to disease.
BCG trials operations manager Cameron Taylor said vetch was now highly valued as a break crop by Mallee growers, predominantly for its ability to grow well in the region’s alkaline soils and biologically fix nitrogen to the soil.
“Additionally, vetch also provides an opportunity to control resistant grass weeds because of its multi-option end-use,” he said.
“It can be grazed, cut for hay to prevent weeds setting seed, brown manured at the time of weed seed set, or harvested for grain.”
According to the findings from a three year investigation carried out by BCG, a vetch crop can deliver nitrogen benefit to subsequent cereal crops for two years.
Through the GRDC-funded investigation which concluded last year, residual nitrogen from vetch brown manure (terminated in the previous years) was shown to carry over for two years.
BCG researcher De-Anne Ferrier said, however, that the challenge for growers in dry environments such as the Mallee, was to find the balance between conserving soil water and fixing soil N.
“On the back of last year’s very dry season, the trial confirmed what we all know – in Decile 1 and 2 rainfall years soil water is more critical than nitrogen,” she said.
Nevertheless, there are options for growers wanting to maximise the nitrogen delivered to soils by pulse crops, namely through inoculation.
Inoculating legume seed ensures that a large number of effective nitrogen-fixing bacteria are in close proximity to the emerging legume root to optimise nodulation and subsequent nitrogen fixation.
A BCG research trial carried out in 2013 confirmed this, showing economic benefits from inoculating legume seed, with the best results achieved if the soil is moist and residual soil nitrogen and soil rhizobia populations are low (Ferrier et. al., 2013).
The value of inoculating legumes will be tested again by BCG this year (2015) with a range of commercial products being put to the test.
The aim is to compare different inoculant types in the Mallee which, in turn, will help local growers make informed decisions about crop inputs in coming seasons.
The vetch variety trial and inoculant product comparison feature among an extensive 2015 BCG research program which boasts 100 trials at sites spread across the Wimmera and Mallee.
BCG invites growers to hear more about this and other BCG research via its fortnightly technical bulletin or at one of the many grower events being held through the season.
To become a BCG member phone (03) 5492 2787 or go to: www.bcg.org.au
