Americas and Oceania Group - International Plant Nutrition Institute

etter than 4.5 t/ha. Tylers/Agwise also achieved the highest gross margin of AUD 564/ha, and four other
groups got gross margins over AUD 500/ha. There were no “silver bullets” in the plans, the results here are
the consequence of the whole package.
Nitrogen was generally not a limiting factor over the whole this season. The two top yielding groups
exceeded the predicted N limit maybe because the crops exploited N deeper than the soil test went. Nitrogen
fertilizer recovery in the grain was higher for the higher yielding crops were around 50% and less than 40%
for the lower yielding crops.
Up front, N was probably associated with lower grain protein, but yields were generally good. 2011 was a
tough year to make decent grain protein—even the high N users tended to stimulate yield more than protein.
Lower yields tended to have higher proteins. Phosphorus was generally well supplied, and on average across
the site, the P off-take was the same as the amount of P applied. Stripe rust was the main disease; present at
varying levels depending on variety susceptibility and use of fungicides. In determining final gross margin,
yield seemed more important than price. Keeping costs down was more important than forcing up quality.
ANZ-11
Tactical Use of Nitrogen in Canola to Manage Risk and Include Break Crops in Northern Wimmera
Project Leader: Felicity Pritchard, PACE Consulting, Horsham, Victoria. E-mail: oilseed@bigpond.com.au
A trial was undertaken to determine if N rates for canola can be reduced in the Wimmera without loss of
yield. It also aimed to determine how late N can be topdressed. There was no response to a low rate of N,
while 50 kg N/ha when applied at or near sowing gave a 54% yield increase, and 100 kg N/ha application
raised yields a further 14%. Nitrogen rate is therefore very important, but timing—when applied even up until
early flowering—had little effect. Soil test N at sowing was 41 kg N/ha, and this would have carried the crop
through the early growth. The crop showed good recovery from N stress when N was applied as late as early
flowering.
Growers in this region base the fertilizer program on expected N demand based on a water limited yield
potential. A total 80 kg N/ha/tonne of grain yield—the popular “rule of thumb”—has stood up as the best
treatment over a range of timings. However, results from this trial suggest a lower rate (60 kg) can provide
similar yields as long as it is applied early.
This field experiment confirmed that canola can respond to late applied N (early flowering) but less
efficiently than earlier applied N in a season with a dry spring. ANZ-12
Multinutrient Deficiencies in Northern Grains Cropping
Project Leader: Mike Bell, University of Queensland, Kingaroy, Queensland. E-mail: mbell4@uq.edu.au
We continue to see evidence of responses to additional P, K, or S fertilizer applications in winter and
summer crops, with a number of sites responding more strongly to combinations of these nutrients (i.e. P
and S, or PK and S) than due to individual nutrients alone. This is especially the case where sufficient N is
available to allow higher yield targets to be reached. Factors which affect root system efficiency or the ability
of root systems to explore large soil volumes (e.g. lesion nematode activity or water logging) will increase the
size of yield responses.
In the recent wet summer and winter crop seasons, the reliance on deep placement of P or K has generally
been reduced in favor of overall profile (0 to 25 cm) enrichment, but residual effects of deep P applications
are still being recorded six crop seasons after application.
It is proposed that application strategies for P and K fertilizer be developed around periodic deep (15 to
20 cm) applications in bands 50 cm apart (or closer), in addition to the current use of starter P applications
in the seeding row when Colwell-P tests in the 0 to 10 cm layer indicate a deficiency. Applications should at
least meet likely crop removal in grain until the next application event, while redistribution of deep applied
nutrient in crop residue will enrich the topsoil layers. Applications of the more mobile N and S can be made
to target individual crops and yield targets as at present. ANZ-13 v
IPNI Interpretive Summaries 59