Row spacing in a
A rule of thumb is to allow a travel speed
30cm (12 inch) row spacing in of 1km/hr for every inch of row spacing
no-till will work: when using a knife point operating at
Farming − If weed control does not rely on crop
7-8cm depth and press wheels. The
optimum speed will vary with machine and
sowing conditions. If possible, get someone
− If it allows you to change the way you else to drive and walk behind the seeder
sow (e.g faster, earlier, fewer seeder to see what is happening to the soil at
fills, wider machine with difference speeds.
same tractor). Timing of operations is also a consideration.
If an individual farm has a large area to sow,
− If it allows you to change your seed 30cm row spacing or wider allows are larger
bed preparation which then increases area to be sown in a shorter space of time
efficiency or capacity. in a no-till system.
− If the impact of wider row spacing on Is yield affected by row spacing?
crop nutrition is taken into account. Research in WA showed that cereal yields
− If it allows you to use other are slightly reduced at wide row spacing
advantageous technology. (30cm) if the spread of seed within the row
is confined to 2.5cm (Amjad and Anderson
2006). This equates to a 1% reduction
What is the optimum in yield for every 2.5cm over 17.5cm row
row spacing? spacing. Yield loss is minimised if the spread
of seed within the row is increased (i.e
Most no-till systems range between 22.5cm an increase in seed bed utilisation, SBU).
and 30cm row spacing. Many farmers have Increased SBU can lead to a reduction
opted for 30cm row spacing. Row spacing in efficacy of the IBS trifluralin and the
is generally a compromise between ease competitiveness of the crop row, but the
of stubble handling, optimal seed bed latter can be compensated for by increasing
utilisation, weed competition, optimum sowing rate.
travel speed and soil throw and hence
effective use of pre-emergent herbicides. Try to spread seed across the disturbed
For example 30cm spacing allows greater width of soils where practical, and ensure
travel speed and therefore more soil throw that the sowing technology (eg. a proven
as well as good trash clearance and the spreader boot) you use for this is reliable
ability to inter-row sow with ease. Narrower and does not reduce germination.
spacings such as 22.5cm provide better What about weed competition?
weed competition but restrict travel speed
Research data suggests that ryegrass
and trash clearance and are more difficult
populations can be higher under wide row
for inter-row sowing. spacing (Figure 1). However, wider row
spacing allows greater travel speed which
How does row spacing affect
causes greater soil throw, so robust rates
sowing speed? of pre-emergent herbicides can be used
Optimum travel speed depends on row effectively. In a 4 year trial in WA, the effect
spacing, soil type and soil moisture. of wider rows on ryegrass numbers was
Optimum travel speed allows enough soil minimal by the fourth year. Less weed seeds
throw to allow incorporation of emerge in the undisturbed inter-row. It was
pre-emergent herbicides without landing found that sowing rate was much more
herbicide treated soil in the adjacent drill important than row spacing in reducing
row (which may cause crop damage). weed numbers (Minkey et al. 2001).
Should I vary row spacing for
800 Many no-till farming operations are sowing cereals and
canola at 30cm spacing.
Heads /m2 400 Oaten hay: Optimum row spacing for oaten hay
production is around 17.5cm to reduce stem diameter,
Row Spacing avoid lodging and to keep the hay windrow off the
50 100 200 mm ground during curing. Cross sowing if using wider row
spacing may achieve the same result.
Seeding rate kg/ha
Pulses: Lentils can be grown on 30cm spacing but may
lodge, causing harvest problems if there is no stubble
present to support them. Sowing between the rows of
Figure 1. Row spacing and seeding rate standing stubbles has increased harvestability of lentils.
interaction with ryegrass competition in
wheat. Source: Minkey et al. (2001) Lupins, faba beans and chickpeas have been sown on
wider rows (35.5cm – 61cm). Reasons for this include:
BCG trials from 1997-1999 underlined the importance of water harvesting in low rainfall environments, reducing
using effective herbicides where crops are sown on wide disease risk by improved airflow and reduced spray costs
row spacings. In paddocks where herbicides were not by using banded spraying.
available for weed control due to resistance, cereal crops
on 17.5cm row spacing out yielded crops on 35.5cm row How does row spacing affect my
spacing due to the increased competition.
ability to inter-row sow?
What are the crop nutrition implications The ability to sow back between the row of a previous
of different row spacings? crop is proving beneficial in reducing the impact of cereal
root and foliar disease and for improved harvestability
P and Zn nutrition: Initially when shifting into no till of lentils. A minimum of 30cm row spacing is suggested
and wider rows, there could be less soil mixing and for inter-row sowing using 2cm guidance systems.
mineralisation (Rainbow 2004). Adequate P and Zn Narrower row spacing can be used in conjunction with
nutrition in no-till systems is particularly important due inter-row sowing, however it is more difficult to achieve
to the increased risk of rhizoctonia, especially in the early (McCallum 2005).
years of no-till.
Fertiliser toxicity: Germination and establishment can Should I modify existing machinery
be affected where too much fertiliser is placed near the or buy new?
seed. For a given band width of seed, the safe rate of Both options can be viable depending on machinery
fertiliser that can be applied in the drill row with the modification skills and/or financial situation.
seed decreases as row spacing increases (Table 1). Canola
is particularly sensitive to fertiliser toxicity, especially, If intending to modify an existing machine, be aware that
when sowing in light textured dry soils. Fertiliser toxicity the value of your existing machinery to a dealer may be
can be avoided by placing some fertiliser below the seed significantly decreased, particularly if the frame is altered.
or by increasing seed spread within the row (greater seed Do your sums on the real cost of modification, including
bed utilisation) (Rainbow 2003). extra hose kits if double shooting. Work out the cost of
upgrading an existing machine compared to a purpose
Table 1. Approximate safe rates of N kg/ha built no-till seeder.
with the seed of cereal grains if seed bed has
good soil moisture (at or near field capacity) References
for 7 and 12 inch row spacing. Use half these Amjad M and Anderson K.W (2006) Managing yield reductions
rates on dry soil. from wide row spacing in wheat. Australian Journal of
Experimental Agriculture, 46, 1313-1321
Soil Texture Minkey, Reithmuller & Hashem (2001), Effect of row spacing
Seed Light Sandy Medium- Heavy and seeding rate of wheat on the emergence and competitive
Spread Loam (loam to clay) ability of annual ryegrass in a no-tillage seeding system.
Agriculture Western Australia, Merredin Dryland Research
17.5cm 30cm 17.5cm 30cm Institute, Crop Updates.
25mm 20 11 25 15 McCallum, M (2005), Inter row sowing. Yorke Peninsula
Alkaline Soils Group Annual Results Book
50mm 40 22 50 30 Rainbow R (2003) Seed Bed Utilisation: A better concept for
calculating maximum fertiliser rates in the seed row. SANTFA.
100mm 80 44 100 60
Rainbow RW and Slee DV (2004) The Essential Guide to No-till
Source: Rainbow (2003) Farming (South Australian No-Till Farmers Association).
T h i s w o r k w a s s u p p o r t e d b y G R D C , B i rc h i p C ro p p i n g G ro u p a n d V N T FA
Birchip Cropping Group t 03 54922787 f 03 54922753 email@example.com PO Box 85, Birchip, 3483 www.bcg.org.au
VNTFA t 03 53820422 f 03 53820477 P.O Box 1397, Horsham, 3402 www.vicnotill.com.au