Reducing the Impacts of Weeds

Dr. Robert Martin - NSW Department of Primary Industries, GRDC

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

This project has demonstrated very clearly the importance of weed control in no-till farming systems and that crop rotation is imperative for the system to be successful.

In wide row no-till cropping systems

What is the problem?

Growers have been reluctant to use chickpeas, faba beans and canola in their rotations because of the difficulties in controlling weeds. This project was able to define the yield-loss versus weed density relationships for these alternative crops and then investigate several different aspects of agronomy that may advantage the crop and reduce the impact of weeds.

What did the research involve?

Nine separate field experiments were completed during the three year project from 2001-2003.

The aims of the project were to examine crop by weed interactions to determine:

  1. how competitive grass and broadleaf weeds are in reducing yield in wide row no-till chickpeas, faba beans and canola
  2. how competition varies with crop planting patterns and weed position
  3. if fertiliser placement and herbicide strategies can be better managed to benefit the crop more than the weeds
  4. if mimic weeds can be used in competition studies to simulate actual weeds
  5. how long post emergent herbicide applications can be delayed in chickpeas before yield reductions occur


What were the key findings?

The order of the crops that were least affected by weeds was wheat, canola, faba beans and chickpeas.

In fact, weeds were twice as competitive in chickpeas, faba beans and canola than in wheat at a weed density of 10-20 plants per square metre. This emphasises the importance of weed control in chickpeas due to their slow growth rate. The wider row spacings used for faba beans, chickpeas and canola generally resulted in lower yields in the presence of weeds. However, when weeds were adequately controlled, the advantages of wider rows outweighed the disadvantages.

The use of post emergent herbicides to control weeds in chickpeas could be delayed 10 weeks after sowing without significant yield loss being experienced.

Precision fertiliser placement in the crop rows has the ability to advantage the crop rather than the weeds. These tend to grow between the rows more than in the crop rows.

Final comment

Overall the project was able to demonstrate several different agronomic strategies for overcoming the effect of weeds.


2016 - Australia - Dr. Robert Martin - NSW Department of Primary Industries, GRDC
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