Soil nitrogen - crop response calibration relationships and criteria for winter cereal crops grown in Australia

Bell, Michael J., Strong, Wayne, Elliot, Denis and Walker, Charlie (2013) Soil nitrogen - crop response calibration relationships and criteria for winter cereal crops grown in Australia. Crop and Pasture Science, 64 5: 442-460. doi:10.1071/CP12431


Author Bell, Michael J.
Strong, Wayne
Elliot, Denis
Walker, Charlie
Title Soil nitrogen - crop response calibration relationships and criteria for winter cereal crops grown in Australia
Journal name Crop and Pasture Science   Check publisher's open access policy
ISSN 1836-0947
1836-5795
Publication date 2013-08-22
Year available 2013
Sub-type Article (original research)
DOI 10.1071/CP12431
Volume 64
Issue 5
Start page 442
End page 460
Total pages 19
Place of publication Collingwood, VIC, Australia
Publisher C S I R O
Collection year 2014
Language eng
Formatted abstract
More than 1200 wheat and 120 barley experiments conducted in Australia to examine yield responses to applied
nitrogen (N) fertiliser are contained in a national database of field crops nutrient research (BFDC National Database). The
yield responses are accompanied by various pre-plant soil test data to quantify plant-available N and other indicators of soil
fertility status or mineralisable N. A web application (BFDC Interrogator), developed to access the database, enables
construction of calibrations between relative crop yield ((Y0/Ymax)X100) and N soil test value. In this paper we report the
critical soil test values for 90% RY (CV90) and the associated critical ranges (CR90, defined as the 70% confidence interval
around that CV90) derived from analysis of various subsets of these winter cereal experiments.
Experimental programs were conducted throughout Australia’s main grain-production regions in different eras, starting
from the 1960s in Queensland through to Victoria during 2000s. Improved management practices adopted during the period
were reflected in increasing potential yields with research era, increasing from an average Ymax of 2.2 t/ha in Queensland in the 1960s and 1970s, to 3.4 t/ha in South Australia (SA) in the 1980s, to 4.3 t/ha inNewSouth Wales (NSW) in the 1990s, and 4.2 t/ha in Victoria in the 2000s. Various sampling depths (0.1–1.2 m) and methods of quantifying available N (nitrate-N or mineral-N) from pre-planting soil samples were used and provided useful guides to the need for supplementary N. The most regionally consistent relationships were established using nitrate-N (kg/ha) in the top 0.6m of the soil profile, with regional and seasonal variation in CV90 largely accounted for through impacts on experimental Ymax. The CV90 for nitrate-N within the top 0.6mof the soil profile for wheat crops increased from 36 to 110 kg nitrate-N/ha asYmax increased over the range 1 to >5 t/ha. Apparent variation in CV90 with seasonal moisture availability was entirely consistent with impacts on experimental Ymax. Further analyses of wheat trials with available grain protein (~45% of all experiments) established that grain yield and not grain N content was the major driver of crop N demand and CV90.
Subsets of data explored the impact of crop management practices such as crop rotation or fallow length on both preplanting profile mineral-N and CV90. Analyses showed that while management practices influenced profile mineral-N at planting and the likelihood and size of yield response to applied N fertiliser, they had no significant impact on CV90. A level of risk is involved with the use of pre-plant testing to determine the need for supplementary N application in all Australian
dryland systems. In southern and western regions, where crop performance is based almost entirely on in-crop rainfall, this
risk is offset by the management opportunity to split N applications during crop growth in response to changing crop yield
potential. In northern cropping systems, where stored soil moisture at sowing is indicative of minimum yield potential, erratic winter rainfall increases uncertainty about actual yield potential as well as reducing the opportunity for effective in-season applications.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Queensland Alliance for Agriculture and Food Innovation
Official 2014 Collection
 
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Created: Wed, 14 Aug 2013, 09:56:32 EST by Associate Professor Michael Bell on behalf of Centre for Plant Science