Extra crop competition with weeds by increasing wheat seeding ratePeter Newman

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The AHRI Communication Team(Peter Newman, Brogan Micallef & Lisa Mayer)

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Seeding rate(kg/ha)

Ry

eg

ras

s h

ea

ds

/m2

Row spacing(mm)

David Minkey, Merredin

Near perfect data set from the 90’s

It’s possible to improve competition with weeds byReducing row spacingIncreasing seeding rateBoth!

30 kg/ha60 kg/ha

90 kg/ha120 kg/ha

0

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Brome + ryegrass seed heads /m2

7" Rows

14" Rows

Seeding rate

Row spacing

1999 - Mingenew

• More practical seeding rates & row spacings

• Increasing competition reduces weed seed set

• Little benefit in increasing seeding rate above 60 kg/ha

Pan

icle

s /m

2

2012 – MingenewMinus Sakura

40kg/ha 80kg/ha 120kg/ha 160kg/ha0

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Seeding rate

Rye

gra

ss s

eed

s /m

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• Increasing the wheat seeding rate decreases ryegrass seed set in the absence of pre-emergent herbicide

40kg/ha 80kg/ha 120kg/ha 160kg/ha0

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Seeding rate

Ryeg

rass

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ds /

m2

• Higher wheat seeding rates significantly reduced ryegrass seed set where Sakura was applied pre-sowing

2012 – MingenewPlus Sakura

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120kg/ha 160kg/ha

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Screenings %

Mingenew

Binnu

Seeding Rate

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s %

Many growers comment that high wheat seeding rates results in high wheat screenings levels (small grain).

However, these two trials and many more like them show that there is no impact of high wheat seeding rates on screenings

40 kg/ha 160 kg/ha

• Impact of high wheat seeding rates on wild radish growth

• The radish were present in a narrow, un-sprayed strip across the trial

Binnu trial 2012Wild radish

40kg/ha 80kg/ha

120kg/ha 160kg/ha

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wheat dry weight

radish dry weight m2

Seed rate

Dry

wei

gh

t (g

/m2)

Un-sprayed radish

• High wheat seeding rates increased wheat biomass & decreased wild radish biomass

Wheat & radish dry weight

40kg/ha 80kg/ha 120kg/ha 160kg/ha0

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Wheat seeding rate

Wh

eat

yiel

d (

kg/h

a)

• Problem with high seeding rates is often no responsein wheat yield

• 40 kg/ha seed rate achieved optimal wheat density

• Increased cost without increasing yield

Wheat yield

40kg/ha80kg/ha

120kg/ha160kg/ha

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Minus SakuraPlus Sakura

Seeding rate

Wh

eat

yiel

d (

kg/h

a)

Wheat yield

Summary

• Increasing the seeding rate is a simple, effective method to increase crop competition

• Often requires an increase in cost & is an inconvenience at seeding time, often with no yield benefit

• Limit to the extra competition that can be achieved

• May be more cost effective to increase crop competition through row spacing & crop row orientation