[ASC-media] WHEN VERY DENSE IS VERY SMART: GRDC Crop Doctor
brendon at iinet.net.au
Wed Aug 30 02:54:32 CEST 2006
WHEN VERY DENSE IS VERY SMART
Lupins sown at high densities competed better against ryegrass in Department
of Agriculture and Food cropping trials at Merredin and
Dalwallinu.<?xml:namespace prefix = o ns =
Grains Research and Development Corporation supported researcher Bob French
has subsequently recommended a lupin planting density of at least 40
plants/M2 to avoid ryegrass blowouts.
Dr French found the amount of ryegrass varied between treatments in each
trial, with a clear downward trend as crop density increased.
In particular, ryegrass was much more prevalent when the crop density was
less than 40 plants/m2.
Lupins did not compete as well with ryegrass once it germinated, but growing
lupins in wider rows did not necessarily mean more ryegrass germination.
At Dalwallinu there was more ryegrass with wide row spacings at high
densities, while at Merredin there was more ryegrass with narrow rows at low
One explanation might be the greater soil disturbance with narrow spacings
at Merredin when sowing, which could have increased ryegrass germination.
The Dalwallinu site was deep ripped before sowing.
Dr French said more research might be needed, but the results at least
suggested wide rows might exacerbate any ryegrass problems.
But he said wide rows still had a place because they allowed weeds in the
inter-row areas to be sprayed with cheap, non-selective herbicides.
Grain yield increased with increasing density to at least 80 plants/m² at
Dalwallinu, a typical response seen many times in past research in the
absence of weeds. Yields at Merredin were very low due to frost damage.
Crop topping can also control ryegrass and should be used in conjunction
with high planting densities.
The Crop Doctor is GRDC Managing Director, Peter Reading, Tel 02 6272 5525
Further Information: Dr Bob French, Tel 9081 3126
Brendon Cant & Associates
Public Relations & Marketing
4 Gugeri St
Claremont WA 6010
Tel 08 9384 1122
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