Assessment of the rate of weed seed decay in chaff-lining systems of South Australia


Research organisatons
Funding source

Trial details

Researcher(s) Daniel Peterson
Year(s) 2019
Contributor SARDI Minnipa Agricultural Centre
Trial location(s) Site 8, Minnipa, SA
Assessment of the rate of weed seed decay in chaff-lining systems of South Australia locations

Failure to control annual weed species that persist through cropping phases facilitates replenishment/establishment of weed seedbanks. Consequently, this maintains weed interference in subsequent years of crop production. Harvest weed seed control (HWSC) has been widely adopted in Australia since its inception over three decades ago to prevent redistribution of weed seeds across cropping fields during commercial harvesting operations (Walsh et al. 2017). Implementation of HWSC obstructs fresh seedbank inputs by subjecting the weed seed bearing chaff fraction to a treatment, such as combustion (narrow windrow burning), mechanical pulverisation (impact mills), decomposition (chaff-lining) and removal (chaff cart). Chaff-lining has been readily adopted by growers because of the low cost of modifying a harvester to confine the chaff fraction into a narrow row between stubble, or onto dedicated wheel tracks in controlled traffic farming systems (chaff-tramlining). There is a paucity of literature examining seedbank decline of important Australian weed species in chaff-lines, however a common conjecture is that a mulching effect is created by a combination of physical and chemical influences (Walsh et al. 2018). Field observations suggest that in the absence of seed decay, control failures of annual weed species and volunteer crop plants may be exacerbated. Therefore, growers urgently need information that substantiates the implications of chaff-lining to weed seedbanks.

Key messages
  • Investigation of weed seedbank decline in nine chaff-lining systems of South Australia demonstrated that growers are achieving high concentration of weed seeds and crop residue at harvest.
  • Assessment of the viable weed seed fraction after crop harvest suggests that large residual annual ryegrass, brome grass and Indian hedge mustard seedbanks have been established in cropping field because these species did not decay over the summer-autumn period in chaff-lines.
  • Evaluation of chaff-tramlining systems showed that annual ryegrass seedbank decline is independent of chaff-line configuration and chaff density.
  • The stability in the weed seedbanks in chaff-lines were consistent with the dry conditions over the summer-autumn period.
  • Growers should be cautious of the magnitude of viable weed seeds in chaff-lines before the cropping season and expect variability in the effectiveness of this tactic between seasons.
Lead research organisation School of Agriculture, Food and Wine - The University of Adelaide
Host research organisation SARDI Minnipa Agricultural Centre
Trial funding source GRDC UA00156
Related program N/A

The research undertaken as part of this project is made possible by the significant contributions of the growers through both trial cooperation, Jerel Fromm, Ian Noble and Ed Hunt on EP, and the support of the GRDC in project UA00156. Thank you to Ian Richter, Katrina Brands, Bradley Hutchings and Steve Jeffs (SARDI) for their technical input to the EP samplings.

Other trial partners Not specified
Download the trial report to view additional trial information


Crop type Mixed species
Treatment type(s)
  • Crop: Type
Trial type Experimental
Trial design Randomised

Minnipa 2019

Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Download the trial report to view additional method/treatment information
Trial source data and summary not available
Check the trial report PDF for trial results.
Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Site 8, Minnipa, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Site 8, 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 Site 8, Minnipa SA
2019 274.8mm
2018 293.5mm
2017 323.8mm
2016 315.3mm
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.

Site 8, Minnipa SA


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 report and links

2019 trial report

Trial last modified: 15-06-2020 13:59pm AEST