Wider rows: more practical but lower yield

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Two light blue water drops on a darker blue backgroundMaintaining row spacing at 30cm increased WUE by 6 to 13 per cent compared with 37.5cm row spacing.

Research by Riverine Plains Inc under the GRDC’s Water Use Efficiency Initiative has found the move to a wider row spacing of 37.5 centimetres has few benefits beyond allowing easier inter-row sowing

Research trials in Coreen, NSW, and Bungeet, Victoria, suggest that going any wider than a 30-centimetre row spacing reduces wheat yield and dry matter production. This is mainly due to increased evaporation from the wider row spacing – even in full stubble retention systems.

The five-year GRDC Water Use Efficiency Initiative trial, which started in 2009, is comparing 22.5, 30 and 37.5cm row spacings in a wheat-canola sequence with two years of wheat following a canola break.

Wider row wheat photo

Moving to a row width of 37.5 centimetres makes cropping operations easier but can incur a yield penalty of about 10 per cent compared with a narrower spacing of 22.5cm.

Three years of trial data show that moving from a 22.5cm row spacing to a 37.5cm spacing incurs about a 10 per cent yield penalty in wheat (Table 1). The response has been consistent across seasons with even the drier year of 2009 showing a yield penalty at the widest row spacing. However, during this same dry year there was no yield penalty incurred by a shift from a 22.5cm to a 30cm row spacing – indicating that wider rows in drier seasons can yield well while delivering operational benefits.

The narrowest row spacing (22.5cm) has consistently generated the highest wheat yield, with a three to six per cent yield penalty for 30cm rows and a 10 to 13 per cent penalty for a 37.5cm row spacing.

Yields suffer at wider row spacings because of lower water use efficiencies (WUEs), with about 14 per cent more unproductive water (run-off, drainage, evaporation and leftover plant-available water at harvest) associated with the wider spacings than the narrower 22.5cm spacing (Table 2). 

The yield penalty incurred by wide rows needs to be balanced against their operational advantages of speedier operations, stubble clearance, inter-row sowing and reduced seeding assemblies.

More information: 

Nick Poole, Foundation for Arable Research New Zealand,
poolen@far.org.nz,
+64 3325 6353

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Table 1: Relative yield loss (%) due to wider row spacing (average of the Coreen, NSW and Bungeet, Victoria sites 2009–2011)
Row spacing 1st wheat (first wheat after the canola break) 2nd wheat (wheat on wheat)
22.5cm (9") 100 100
30cm (12") 93 97
37.5cm (15") 87 90
Table 2: WUE of the 2010 wheat crop (following canola) at Coreen, NSW.
Row spacing Dry matter (t/ha) Yield (t/ha) WUE1 (kg/mm) Unproductive water2 (mm)
1 Water use efficiency based on 570mm rainfall (April to mid-November) including stored water but no evaporation.
2 Unproductive water (evaporation, run-off, drainage and plant-available water left at harvest) = growing season minus transpired water.
22.5cm (9") 16.5 6.2 10.9 271
30cm (12") 15.2 5.8 10.2 292
37.5cm (15") 14.4 5.5 9.6 308

GRDC Project Code SFS00017

Region South, North