Variable rate nitrogen

CC BY 4.0

Research organisaton
Funding source

Trial details

Researcher(s) Nicole Dimos (SPAA)
Felicity Turner (Vision Ag)
Grant Yates (Vision Ag)
Year(s) 2011
Contributor Society of Precision Agriculture Australia
Trial location(s) Coonalpyn , SA
Variable rate nitrogen locations

To compare the effects of variable rate nitrogen applications on wheat yield across varying soil types.

Key messages

The trial has indicated that the application of the high rate UAN (140L/ha) over the entire paddock still proved to be a more profitable than applying the low rate over the entire paddock, however the overall gross margin benefits are not as visible due to the low yielding sand zone only occupying 9ha (13%) of the paddock. However these results confirm that the adoption of PA is an economically sound decision, indicating that the grower could make a saving of $48/ha if that extra nitrogen was not applied to the low yielding area via the use of variable rate fertiliser application. The trial results have solidly indicated that the overall gross margin would be profitably affected not having to spend the extra $62/ha on fertiliser. The gain of $53/ha in the high yield zone with high rate N (140L) is a substantial increase in profit over the low rate (60L) showing there is benefits to adding N in these zones.

Lead research organisation Society of Precision Agriculture Australia
Host research organisation N/A
Trial funding source GRDC SPA000010
Related program N/A

This project was funded by the Grains Research and Development Corporation (GRDC)

Other trial partners AAron and Trent Long (property owners)
Download the trial report to view additional trial information


Crop type Wheat
Treatment type(s)
  • Fertiliser: Rate
  • Soil: Type
Trial type Precision agriculture
Trial design Not applicable

Coonalpyn 2011

Sow rate or Target density 80 kg/ha
Sow date 14 May 2011 14 May 2011
Harvest date Not specified
Plot size Not specified
Plot replication Not specified

Variable rate UAN

Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Treatment 1
Treatment 2
Grain yield (t/ha)
1 Low yield zone (sand) UAN @ 140 L/ha 1.62
2 Low yield zone (sand) UAN @ 60 L/ha 1.56
3 Low yield zone (gravel) UAN @ 140 L/ha 3.02
4 Low yield zone (gravel) UAN @ 60 L/ha 2.61
5 Medium yield zone UAN @ 140 L/ha 3.23
6 Medium yield zone UAN @ 60 L/ha 2.98
7 High yield zone UAN @ 140 L/ha 3.78
8 High yield zone UAN @ 60 L/ha 3.28

Grain yield t/ha

Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Coonalpyn , SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Coonalpyn , SA Calcarosol
Soil Moisture Source: BOM/ANU
Average amount of water stored in the soil profile during the year, estimated by the OzWALD model-data fusion system.
Year Coonalpyn SA
2011 554.6mm
2010 547.9mm
2009 502.7mm
2008 496.7mm
2007 515.9mm
2006 535.7mm
2005 541.9mm
2004 543.3mm
2003 533.6mm
2002 510.1mm
2001 534.6mm
2000 527.4mm
National soil grid Source: CSIRO/TERN
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties



Derived climate information

No observed climate data available for this trial.
Derived climate data is determined from trial site location and national weather sources.

Coonalpyn SA

NOTE: Exact trial site locality unknown - Climate data may not be accurate

Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.

Trial last modified: 30-09-2019 16:11pm AEST