- Overall effect of retained stubble treatments was to reduce poppy plant size and vigour.
- Grower treatment resulted in the highest poppy plant numbers, but also highest radish numbers.
- Retaining standing stubble resulted in lowest poppy establishment.
- Very high levels of RLEM damage were recorded across the trial where stubble had been retained.
- Windrow burning and burning stubble showed potential as stubble management techniques.
Stubble retention is gaining momentum is Tasmania, at least for part of the rotation, as growers update their equipment and increase utilisation of irrigation. However the diversity of cropping, which includes small seed crops such as poppies and broadacre vegetable production, in rotation in grain growing areas, means that conventional cultivation is currently still very much a part of the program.
As part of the GRDC-funded stubble project (BWD00024), the Tasmanian branch of SFS designed field trials to test the viability of retaining stubble prior to seeding poppies – an important cash crop for many Tasmanian growers.
This work will now have significance for Victorian growers as the poppy industry expands in the western districts.
SFS research: 2014
A trial was established at ‘Rokeby’, Cressy in 2014 examining ‘short rotation break crops for managing stubble and soil health’.
The aim of the trial was to evaluate the effects of retaining, burning or cultivating wheat stubble on establishment of poppies sown in July.
Trial Treatments included:
- Windrow burn
- Retain standing
- Cultivated (Grower treatment was also cultivation)
The results showed that retaining stubble had a negative effect on poppy establishment, growth and vigouor.
|Table 1: Poppy and radish emergence and RLEM presence|
|Windrow burn||48.6 a||1.8 b||4|
|Retain/standing||27.3 c||2.2 b||5|
|Burnt||46.5 a||2.0 b||4|
|Cultivated||39.7 ab||1.0 b||3|
|Grower||55.8 a||10.0 a||1|
RLEM ratings: 1 = 1-2 RLEM/m2; 2 = Present on <10% plants no vigour reduction; 3 = Present on 10-50% plants some vigour reduction; 4 = Present on >50% plants vigour reduced; 5 = Present or damage on most plants, significant vigour reduction
The 2015 SFS research site will be located on the property of AG Morrison of Pisa Estate, who works on a retained stubble system. Field trials will be established on a paddock sporting poppy stubble.
Prior to sowing the paddock was disced, then grazed, and the remaining stubble left on the surface.
Replicated small plot trials located at this site include:
- Select herbicide efficacy at different timings of application in retained & burnt stubble. Select applied at 0.5l/ha at 1.5 leaf, 3 leaf, early tillering & late tillering.
- Pre-emergent control of ryegrass in canola on a stubble retained system, alternatives to Trifluralin.
- Response of spring wheat variety Trojan to Nitrogen application rates and timing.
For more information on current and future trial work in Tasmania, please contact Heather Cosgriff on 0488 600 722.
This research is being conducted by SFS as part of the GRDC Maintaining profitable farming systems with retained stubble initiative (project BWD00024 Maintaining profitable farming systems with retained stubble in Victoria and Tasmania).