Row orientation and weed competition

CC BY 4.0

Research organisaton
Funding source

Trial details

Researcher(s) Amanda Cook (SARDI)
Ian Richter (SARDI)
Wade Shepperd (SARDI)
Nigel Wilhelm (SARDI)
Year(s) 2015
Contributor Central West Farming Systems
Trial location(s) Minnipa, SA
Row orientation and weed competition locations

To investigate the impact of row direction and row spacing on grass weed competition and cereal performance over three years.

Key messages
  • An east-west (E-W) sowing direction increased yield over northsouth (N-S) sowing direction in an average season.
  • The results showed a decline in yield due to weed competition, but no effect on weed competition due to row direction. So sowing in an E-W direction may give a yield benefit with no difference in weed seed set.
  • The wider row spacing of 30 cm resulted in a yield reduction and greater weed biomass at harvest.
  • There were no differences in yield with ribbon seeding with either 18 or 30 cm row spacings, but ribbon seeding reduced ‘weed’ biomass.
Lead research organisation Central West Farming Systems
Host research organisation N/A
Trial funding source GRDC CWF00020
Related program N/A
  • Thank you to Sue Budarick for processing the weed counts and managing the weed germination trays.
  • Funded by the GRDC Overdependence on Agrochemicals project (CWF00020).
  • Agrochemicals project (CWF00020), which is led by CWFS.

Other trial partners EPARF and SARDI
Download the trial report to view additional trial information


Crop type Wheat
Treatment type(s)
  • Sowing
  • Sowing: Row spacing
Trial type Experimental
Trial design Replicated

Minnipa 2015

Sow date 21 May 2015
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Treatment 1
Treatment 2
Grain yield (t/ha)
1 North-South knife points 2.32
2 North-South knife points + weed 2.95
3 North-South ribbon spread 2.29
4 North-South ribbon + weed 1.87
5 East-West knife points 2.69
6 East-West knife points + weed 2.38
7 East-West ribbon spread 2.66
8 East-West ribbon + weed 2.45

Grain yield t/ha

Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Minnipa, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Minnipa, SA Calcarosol
Soil Moisture Source: BOM/ANU
Average amount of water stored in the soil profile during the year, estimated by the OzWALD model-data fusion system.
Year Minnipa SA
2015 289.3mm
2014 336.5mm
2013 290.8mm
2012 330.8mm
2011 383.4mm
2010 385.3mm
2009 391.3mm
2008 330.4mm
2007 331.2mm
2006 334.5mm
2005 288.0mm
2004 296.1mm
2003 293.2mm
2002 283.3mm
2001 343.9mm
2000 389.0mm
National soil grid Source: CSIRO/TERN
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties



Derived climate information

No observed climate data available for this trial.
Derived climate data is determined from trial site location and national weather sources.

Minnipa SA

NOTE: Exact trial site locality unknown - Climate data may not be accurate

Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from
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.

Trial last modified: 12-03-2019 10:07am AEST