Brendon Cant brendon at iinet.net.au
Wed May 10 10:23:43 EST 2006


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Up to 30 per cent of variable cropping input costs are sunk into fertilisers
and so growers rightly demand a substantial return.


Nitrogen nutrition investment can cost up to $80/ha and so recent research
aimed to ensure that this was not a free meal for wheat crops.


The Grains Research and Development Corporation (GRDC) supported the
Department of Agriculture’s Jeremy Lemon as he investigated how to trickle
out nitrogen so that if yield potential collapsed due to deteriorating
conditions, growers could shelve fertiliser for a better year.


Of course, this requires evidence that withholding nitrogen won’t jeopardise
yield potential or grain quality.


Mr Lemon’s results in the Esperance Port Zone established that nitrogen
timing made no difference to grain protein, while screenings rose and yield
fell if too much went on, as is often the case in poor seasons.


But when applied late in a season with a dry spring, excess nitrogen did not
penalise yield as much as earlier applications.


This was illustrated when nitrogen rates above 100 kg/ha sent yields
backwards after application at tillering, or stem elongation, but not as
severely when added at booting prior to the dry spring of 2004. Under these
conditions, excessive early nitrogen increased screenings, while the same
rates at booting had no affect.


The GRDC-supported research concluded that provided there is stored soil
moisture and rainfall to wash fertiliser into the root zone, there is no
problem adding it as late as booting.


According to Mr Lemon, this supports the strategy of feeding crops more
judiciously throughout the season – not just a ‘big breakfast’.


In dry areas, this means growers can add nitrogen once the season shows
enough promise to repay the investment with strong yields.


In wet seasons, it can be regulated to avoid nutrient leaching and losses
from waterlogging.



The Crop Doctor is GRDC Managing Director, Peter Reading, Tel 02 6272 5525

Further Information: Jeremy Lemon, DAWA Tel 08 9083 1120

GRDC REF: cdmar062.doc/DAW12/Blumenthal

Brendon Cant & Associates
Public Relations & Marketing 
Suite 5
4 Gugeri St
Claremont WA 6010


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