What row-spacing will suit my stubble-retained system

Increasing the row spacing improves stubble handling, but there are both benefits and challenges that come from increasing row spacing in a retained-stubble cropping system. No set row spacing is right or wrong.

The optimum row spacing is the one that suits your individual farming system and will depend on:

  • Machinery including sowing efficiency, preferred seed placement and the cost of machinery set-up or replacement
  • Crops grown and crop safety (herbicide damage and fertiliser toxicity)
  • Yield potential, stubble loads and residue flow
  • Seasons
  • Soil type
  • Weed burden and pre-emergent herbicide efficacy (including soil throw and incorporation of volatile pre-emergent herbicides such as trifluralin)
  • Pest and disease management

Photos of wheat grown in narrow and wide row spacings

Figure 1. There are many benefits to using narrow rows (left) but wide rows (right) are easier to manage in stubble retained systems. Source: WeedSmart: Narrow row spacing: is it worth going back?

Increasing the row spacing improves pre-emergent crop safety and enables most growers to inter-row sow and avoid blockage issues.

However, in most environments there are yield penalties when row spacings are increased substantially. A NSW DPI review of trials around Australia over a number of seasons gave an average yield increase of eight per cent when planting in 18cm rows compared to 36cm rows, unless yields were below 0.7t/ha (via EPARF Economic analysis of reduced row spacing, PDF 897kb).

In drier years in low rainfall environments, crops sown at wider spacings can produce higher yields than those sown narrower, provided stored soil moisture is available during the later stages of crop development.

In recent seasons, there has been a move back to narrower row spacings to improve weed management through increased crop competition. This is due to the increasing incidence of herbicide-resistant weeds and the limitations of using pre-emergent herbicides with disc seeding systems.

In wider rows the concentration of fertiliser in the row is higher than in narrow rows and can lead to fertiliser toxicity. Growers should consider options to separate seed from the fertiliser.

Table 1. The benefits and challenges of narrow and wide row spacing. Source: BCG Row spacing for retained stubble systems in the Wimmera and Mallee

Narrow rows (less than 25cm – environment dependent)

Benefits

  • Increased yield in cereals
  • Better weed competition
  • Better establishment – where stubble load is not an issue
  • Lower potential for evaporation
  • Lower risk of fertiliser toxicity at sowing due to higher seed bed utilisation (SBU)

Challenges

  • Reduced stubble handling ability – more blockages at sowing
  • Increased machinery set up, operation and maintenance costs
  • Reduced pre-emergent herbicide safety (lower rates may be required)
  • Higher risk of disease (i.e. crown rot)

Wide rows (more than 25cm – environment dependent)

Benefits

  • Improved pre-emergent herbicide safety
  • Improved yield in low rainfall environments (season dependent)
  • Better stubble handling (fewer blockages)
  • Easier inter-row sowing
  • Improved sowing efficiencies – faster
  • Lower machinery set up and maintenance costs
  • Improved disease management (i.e. crown rot)
  • Reduced machinery draught – reduced fuel requirements

Challenges

  • Potential for reduced establishment – within row competition
  • Yield penalties in crops sensitive to row spacing
  • Potential for increased evaporation
  • Increased risk of fertiliser toxicity due to low seed bed utilisation (SBU)

More Information

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