Welcome to Crop Nutrition News
Sourcing relevant and recent crop nutrition information is not
always easy; hopefully this newsletter can help. Produced as part
of the More Profit from Crop Nutrition (MPCN) program our aim
is to help you quickly link to crop nutrition information associated
with GRDC RD&E investments.
With a strong focus on developing and extending regional crop
nutrition information MPCN builds on GRDC’s previous crop
nutrition investments.
MPCN is a collaborative initiative supported by GRDC and is
overseen by Jan Edwards, manager ‘Farm Practices’.
By bringing together projects relating to crop nutrition, MPCN’s goals are to:
1.
Increase adoption of crop nutrition knowledge across Australia;
2.
Improve coordination of communication and extension across the grains and fertiliser industries.
3.
Improve tools that are used by grain growers and advisers to improve nutrient use efficiency; and
4.
Document emerging crop nutrition ideas and capacity challenges.
A list of the projects can be found at www.grdc.com.au/mpcn and more details are available in the
January - February 2014 Ground Cover Supplement.
As Coordinator of the MPCN I am keen to learn of your specific crop nutrition needs and to receive feedback
on the program’s outputs.
Spare a moment and answer the 5 questions on the survey.
Simon Speirs
My contacts are - 0428 647 787, [email protected]
Soil testing and understanding soil tests
At recent crop nutrition workshops run in Central
Queensland, as part of the MPCN northern extension
project, Chris Dowling reminded growers of the role of soil
tests in managing soil fertility and crop productivity.
Soil tests should only be taken for a reason, eg to help
identify a problem or to check that soil nutrient levels are on
track. Important times to test are after:
• high or low performing seasons;
• several years of pulse crops; or
• a run of unusually wet or dry seasons
Ideally a soil test result should not produce any surprises
but confirm the anticipated nutrient levels. Perhaps soil tests should be considered more like a fuel gauge,
indicating what is in the tank, rather than a compass telling you where to go.
Other than for mineral nitrogen, soil tests are not a measure of how much nutrient can be extracted from the
soil. Instead they are an index of sufficiency indicating the likelihood and the magnitude of response from
adding nutrient.
Using the nutrient calibration curves produced in the Better Fertiliser Decisions for Cropping Interrogator can
help provide a closer indication of the relationship between nutrient sufficiency and yield.
New regional soil testing fact sheets distributed with the January-February issue of Ground Cover, provide
more details of these response curves.
Submitting a representative sample to a laboratory certified ASPAC proficiency for a key test method eg
Colwell P and working with a Fertcare® accredited adviser can help improve reliability of the soil tests results
and their interpretation.
More information:
Chris Dowling, [email protected]
GRDC Research Code DAQ00183
pH driving nutrient use efficiency in WA
Work in WA has shown that in acidic soils, investing in lime
rather than phosphorus (P) can result in a better financial
return. This is because:
• about 80% of soils in WA cropping zone have surface pH
less than a critical level of pH 5.5.
• low pH not only impacts on nutrient availability, it can
result in root pruning, nutrient uptake and consequently
yield.
• in combination with soil problems such as water
repellence and soil compaction, nutrient use efficiency in low pH soils can be low.
• about 80% of soils in the WA cropping region have phosphorus concentrations above the critical level
(90% maximum. production).
These issues were discussed by Craig Scanlan, DAFWA, and colleagues at the ‘Get to Know Soils Deeper’
workshops run as part of the MPCN extension in the west.
Craig also presented the Crop Phosphorus Model that can help tailor P requirements for specific situations.
More information:
Craig Scanlan, [email protected]
GRDC Research Code DAW00223
Soil Testing for P
While a number of different P tests are used in Australia, the vast
majority of calibration data for soil phosphorus in cropping is for
Colwell P.
Recent research has led to the introduction of the DGT-P test
for cropping. The grains and fertiliser industries are continuing
to conduct fertiliser trials aimed at refining calibration criteria
and understanding the differences between the measure of
phosphorus obtained from DGT-P and from Colwell-P or other
testing methods.
Importantly, the DGT-P test is recommended for soil testing on calcarosols (soils having high levels of “free
lime”). In other cases, contrasting peer-reviewed field knowledge means that more work is required before
recommending either Colwell-P or DGT-P in preference to the other on a number of soil types - it is still early
days.
Despite this general view there are some cases where yield results may not be reflective of expectations
based on an initial soil test. If the issue is indeed related to phosphorus, you may wish to run a comparative
analysis with an alternative P-test such as DGT-P.
However, it is crucial that growers use the same test across paddocks and across years.
Currently, a proficiency program for the DGT-P test has not been established.
The GRDC fact sheet Phosphorus Management produced in November 2012 provides more details for P
tests and PBI.
More information:
Sean Mason, [email protected] or
Simon Speirs, [email protected]
GRDC Research Code UA00140, DAN00166
Nitrogen crucial to early phosphorus response
Victorian DEPI researcher Roger Armstrong has been trying
to understand why early dry matter responses to phosphorus
(P) do not always relate to grain yield.
His team has found that in the Southern Region, unless
nitrogen (N) is applied with P, there may be no grain yield
response.
In trials on a P deficient Vertosol and Calcarosols in the
Wimmera, despite pronounced responses to P fertiliser
during vegetative growth stages, grain yield was increased
only when N was also applied, regardless of soil water
supply.
Phosphorus is especially important in the establishment of root systems and early crop growth but if N is
limiting, optimum use of the P is not made.
More details can be found in Roger’s paper to the 2012 agronomy conference.
In other trials it was shown that canola was better than wheat at accessing P that had become fixed in the
less soluble soil P pools.
More information:
Roger Armstrong, [email protected]
GRDC Research Code DAV00125
Crop and Pasture Science Special Issue, Vol 64, Number 5
Edited by Ken Peverill, Mark Conyers, Robert Norton and the late Doug Reuter, the papers in the Special
Edition are a valuable resource for soil scientists and crop nutritionists.
Arising from the Better Fertiliser Decisions for Cropping Systems in Australia (BFDC) project, these papers
have collated and synthesised historical nutrient response data.
This re-examination of fertiliser response surfaces and soil test interpretations are leading to an improved
understanding of fertiliser management.
Papers in the Special Edition have identified soil testing knowledge gaps for certain crops and nutrients and
have provided a guide for developing future research projects and prioritising resources. Some of these gaps
are being addressed through current MPCN projects.
To source the papers visit http://www.publish.csiro.au/pid/7270.htm
The key practical messages from these papers have been distilled into three regional GRDC fact sheets titled
Soil Testing for Crop Nutrition, available from the GRDC website.
More information:
Simon Speirs, [email protected]
GRDC Research Codes DAN00166, DAN00132, DAW00222, UQ00063, DAN00168
Micronutrient deficiency
Micronutrient deficiencies can be tricky to diagnose and treat. By
knowing your soil type, considering crop requirements and the
season, and supporting this knowledge with diagnostic tools and
strategies, effective management is possible.
Micronutrient deficiencies are best determined by looking at the
overall situation: region, soil type, season, crop and past fertiliser
management.
Tissue testing is the best way to accurately diagnose a suspected
micronutrient deficiency.
When tissue testing, sample the appropriate plant parts at the right time. Plant nutrient status varies according
to the plant’s age, variety and weather conditions.
However, the difference between deficient and adequate (or toxic) levels of some micronutrients can be very
small.
When applying fertiliser to treat a suspected deficiency, leave a strip untreated. A visual response or tissue
testing can confirm whether the micronutrient was limiting.
Useful resources:
GRDC Crop Nutrition Fact Sheet - Micronutrients
CSIRO publication - Plant Analysis: An Interpretation Manual
More information:
Rob Norton, [email protected]
GRDC Research Code IPN0001
Micronutrient deficiency
There are three regional extension projects as MPCN program
Southern Extension project is led by BCG. Crop Nutrition workshops will be run across the southern region
in the winter period, for details contact Ciara Cullen, 03 5492-2787, [email protected]
Western Extension project is led by Craig Scanlan, DAFWA, 08 9690-2174, [email protected]
Northern Extension project is led by Kaara Klepper, Department of Agriculture, Fisheries & Forestry
Queensland, 07 4639-8870, [email protected]
For more information on MPCN activities please visit the visit the events calendar on the GRDC website.
Copyright © 2014 GRDC, All rights reserved.
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