Co-limitation in wheat crops of Eyre Peninsula as a way to better understand N and water economy


Research organisatons
Funding source

Trial details

Researcher(s) Mariano Cossani, Andrew Ware and Victor Sadras (SARDI)
Year(s) 2016
Contributor SARDI Minnipa Agricultural Centre
Trial location(s) Site 6, Minnipa Agricultural Centre, SA
Co-limitation in wheat crops of Eyre Peninsula as a way to better understand N and water economy locations

Within Eyre Peninsula, as in other Mediterranean environments, grain yields of cereal crops are variable, and in many cases, this is due to under-fertilization. Previous modelling and field experiments showed the need for higher rates of fertilization in south-eastern Australia. Research into interactions between water and N, with simulation models and empirical data, has proved that yield, as well as water-use efficiency, is positively related to the degree of co-limitation between water and N [1, 2] .  In other words, yield and water use efficiency increase when the stress produced by water has similar intensity than the stress produced by N. The understanding of how resources co-limit and its genotypic variability in wheat crops of Eyre Peninsula is a key step for improving the water use efficiency and to reduce yield gaps.

This trial is part of a new project which addresses research and development gaps on the interactions between water and nitrogen in Australian cropping systems identified in GRDC scoping study DAS00157. The novelty of this project is a new tool to estimate the actual water and nitrogen stress and co-limitation in the season. The new tool will complement existing tools and provide opportunities to adjust N availability in the season, thereby reducing farmers’ risk and increasing chances of capturing the benefits of wetter seasons. Results are expected to be applicable to the medium to low rainfall areas of south-eastern and western Australia. The current project is focused on management of nitrogen fertilizer under uncertain conditions as related to variable rainfall and changing agronomic practices.

The aim of the current trial was to evaluate the impact of water and N co-limitation on grain yield of wheat under different N and water availability and to assess the genotypic variability in the main parameters.


Key messages
  • Wheat yields increased with the level of water and N co-limitation explored.
  • Higher yield in modern cultivars was partially associated with higher co-limitation.  
  • The higher yield of modern cultivars was related to use efficiency rather than to capture of water and N.
  • Grain yield increased with increasing N uptake per unit of water used.
Lead research organisation South Australian Research and Development Institute
Host research organisation N/A
Trial funding source GRDC DAS00165-BA
Related program N/A

The present project is co-funded by SARDI and GRDC. Special thanks to Leigh Davis, Brenton Spriggs and Sue Budarick for their collaboration with field and lab activities, and to Dr. Alan McKay and his team for advice with the root sampling.

Other trial partners Not specified
Download the trial report to view additional trial information


Crop type
Treatment type(s)
  • Fertiliser: Rate
  • Irrigation: Rate
  • Variety: Type
Trial type Experimental
Trial design Replicated

Minnipa Agricultural Centre 2016

Sow rate or Target density The sowing density was targeted at 180 plants/m2, and rows spaced at 27 cm.
Sow date 13 May 2016
Harvest date 30 October 2016
Plot size 1.6m x 10m
Plot replication 3
Paddock history 2015: Legume pasture 2014: Barley 2013: Wheat
Fertiliser <p>Prior to sowing we applied MAP at a rate of 120 kg/ha. Weeds, pests, and diseases were controlled following the practices used for National Variety Trials (NVT).</p>
Download the trial report to view additional method/treatment information
Trial source data and summary not available
Check the trial report PDF for trial results.
Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Site 6, Minnipa Agricultural Centre, SA Red sandy clay loam
Derived trial site soil information
Australian Soil Classification Source
Trial site Soil order
Site 6, Minnipa Agricultural Centre, SA Calcarosol
National soil grid Source
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



Site 6, Minnipa Agricultural Centre SA 2016

Observed climate information

Rainfall avg ann (mm) 325mm
Rainfall avg gsr (mm) 241mm
Rainfall trial total (mm) 391mm
Rainfall trial gsr (mm) 268mm

Derived climate information

Site 6, Minnipa Agricultural Centre SA


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.