Amanda Cook, Nigel Wilhelm and Chris Dyson (SARDI)
|Contributor||SARDI Minnipa Agricultural Centre|
Site 21, Minnipa Agricultural Centre, SA
Controlling barley grass in upper EP farming systems is becoming a major issue for growers, due to the development of herbicide resistance and delayed weed emergence. Management options other than herbicides need to be considered to address the issue for long-term sustainability. One of the best bets for cultural control of barley grass in-crop may be increased crop competition. The Australian Herbicide Resistance Initiative (ARHI) based at University of Western Australia has shown an increase in grain yield with wheat and barley sown in an east–west (E-W) orientation over crops sown in a north-south (N-S) orientation due to a decrease in ryegrass competition. This effect is due to lower light interception by the weed due to the crop row orientation resulting in a decrease in weed seed (Borger, 2015).
A trial was established at Minnipa Agricultural Centre to investigate the impact of row direction and row spacing on weed competition and cereal performance over twoyears. The previous season’s research is reported in Eyre Peninsula Farming Systems Summary 2015, Row orientation and weed competition, p163.
|Lead research organisation||
Central West Farming Systems
|Host research organisation||
SARDI Minnipa Agricultural Centre
|Trial funding source||GRDC CWF0020|
Overdependence on agrochemicals
Thank you to Sue Budarick, Tegan Watts, Lauren Cook and Katrina Brands for sampling, processing the weed counts and managing the weed germination trays. Funded by the GRDC Overdependence on Agrochemicals project (CWF00020).
|Other trial partners||Upper North Farming Systems, BCG|
|Sow rate or Target density||Weeds (oats as surrogate) 70 plants/m2|
In 2016 a replicated plot trial was sown in blocks with two row orientations; E-W and N-S into a pasture paddock. The ten treatments within the row orientation blocks included two row spacings, 18 cm (7”) and 30 cm (12”), sown with two different seeding boots; a Harrington knife point and an Atom-Jet spread row ribbon seeding boot, both with and without ‘oat weeds’. An ‘oat’ weed only treatment was also sown at both row spacings with the Harrington knife points. Plots were direct drilled with press wheels. Oats were spread at 70 plants/m2 as a surrogate weed through the seeder on the ‘weed’ plots before the seeder pass.
|Sow date||17 May 2016|
|Harvest date||4 November 2016|
|Plot size||20m x 2m|
|Paddock history||2016: Mace wheat 2015: Medic pasture 2014: Wyalkatchem wheat|
18:20:0:0 (DAP) fertiliser at 60 kg/ha
The trial was sprayed on 16 May with a knockdown of 1.5 L/ha of glyphosate, and Broadside (MCPA; bromoxynil; dicamba) at 800 ml/ha on 22 June.
||Screenings (%)||Late dry matter (t/ha)||Protein (%)||Yield (t/ha)||Crop Establishment (plants/m2)|
|1||█ sowing direction E-W||0.9||6.33||10.2||3.36||116|
|2||█ sowing direction N-S||0.9||6.4||10.3||3.3||108|
|3||█ row spacing 18cm||1||7.05||10.3||3.64||120|
|4||█ row spacing 30cm||0.9||5.68||10.3||3.02||105|
|5||█ knife points||0.9||6.13||10.3||4.03||114|
|6||█ knife points plus weed||6.61||2.58||115|
|8||█ ribbon plus weed||2.52||110|
|Rainfall avg ann (mm)||325mm|
|Rainfall avg gsr (mm)||241mm|
|Rainfall trial total (mm)||391mm|
|Rainfall trial gsr (mm)||268mm|
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.