Does increasing soil organic carbon alter nitrous oxide emissions?


Research organisatons
Funding sources

Trial details

Researcher(s) Louise Barton
Year(s) 2012
Contributor SoilsWest
Trial location(s) Buntine, WA
Related trials
Does increasing soil organic carbon alter nitrous oxide emissions? locations
  • To increase understanding of the interaction between increasing soil organic carbon and greenhouse gas emissions. In particular to quantify the influence of soil organic carbon on nitrous oxide and methane emissions in a grains cropping system.
  • To determine whether increasing soil organic carbon lowers the amount of nitrogen fertiliser required for grain production.
Key messages

Growers should continue to be encouraged to employ land management practises that increase SOC in Western Australia’s cropping soils. Increasing soil C benefits crop production, and has the potential to decrease N and other fertiliser needs. Although increasing SOC increased soil N2O emissions (and inhibited CH4 uptake) in the present study, these losses were relatively low.

The greatest risk of N2O emissions from a sandy soil in the Western Australian grain belt occurred in response to summer-autumn rainfall events, and more so with increasing SOC. This observation is consistent with previous observations for semi-arid soils where a large proportion of annual N2O emissions occurred between crop growing seasons, when the soil was fallow, and in response to soil wetting following summer and autumn rainfall. Approaches to decreasing N2O emissions following summer rainfall events is limited to decreasing N2O emissions from nitrification (e.g., liming, nitrification), and increasing soil N immobilisation and plant N update during summer and autumn.

Nitrogen supply (via mineralisation) prior to seeding varied depending on soil type and summer rainfall, and needs to be included when determining annual N fertiliser requirements. Optimising N fertiliser input will increase farm profitability and decrease the risk of N2O emissions arising from under-utilised N fertiliser.

The proportion of N fertiliser applied that was lost as N2O from a sandy soil in the Western Australian grain belt ranged from 0.08 to 0.12%. This finding, plus past research in the Western Australian grain belt, supports further lowering current Australia’s emission factor (0.3%) for calculating N2O emissions from the application of N fertiliser to non-irrigated, cropped soils in Australia’s semi-arid regions.

Lead research organisation University of Western Australia
Host research organisation Liebe Group
Trial funding source Australian Government DAF00004-04
Trial funding source GRDC DAW00222
Related program Commonwealth Filling the Research Gap

This report was written by the Project Leader in partnership with Professor Daniel Murphy (The University of Western Australia) and Dr Frances Hoyle (Department of Agriculture and Food WA).

The authors thank Debra Donovan for maintaining the automated gas chambers and field site at Buntine, and Chris Swain for coordinating soil and plant analyses for all study sites. The Liebe Group are thanked for providing access to the Long Term Research Site at Buntine, and assisting with the establishment and maintenance of the study site. Blakely Paynter, Craig Scanlan, Susanne Cartledge, and Department of Agriculture and Food WA technical staff are thanked for assistance with establishing nitrogen (N) fertiliser research sites and grain analyses. Casual assistance was provided by Richard Bowles, Yoshi Sawada and Simone Wells and other members of the Soil Biology and Molecular Ecology Group. Georgina Holbeche and Matthias Leopold completed the soil classification. K

Other trial partners Department of Agriculture and Food Western Australia
Download the trial report to view additional trial information


Crop types Canola
Treatment type(s)
  • Soil
  • Soil amelioration
  • Soil amelioration: Rate
Trial type Experimental
Trial design Randomised,Replicated,Blocked

Buntine 2012 Canola

Sow rate or Target density 3 kg/ha Telfar
Sow date 7 June 2012
Harvest date 29 November 2012
Plot size Not specified
Plot replication 3

Plots received 40 kg per ha of triple superphosphate inserted to a soil depth of 30 mm at planting. Half the plots in each treatment then received a surface application of urea (100 kg N per ha) four weeks after seeding (10 July 2012).

The N fertiliser application rate was greater than that typically applied by growers in the district so as provide the greatest potential for N2O emissions. 


7/06/2012: 1.2 L/ha roundup attack, 1 kg/ha Atrizine, 2.5L/ha Trifluralin

29/06/2012: 1.1 L/ha atrizane

18/07/2012: 500 ml/ha Clethodim

15/10/2012: 1.7L/ha rRoundup Attack 


29/6/2012: 100 ml/ha Dimetholoate, 100 ml/ha Cypermethrin

Soil amelioration

The current study used field plots amended with (OM+tillage) or without (Tillage) the addition of organic matter (OM) every three years, with both treatments tilled annually. The most recent application of OM (20 t ha-1 of chaff) was in 2012, with a total of 80 t ha-1 applied to the OM+tillage treatments since the study site was established. During the present study, SOC (0–100 mm) averaged 1.20% in the plus OM treatment versus 0.64% in the no OM treatment.

Tillage Disc ploughed prior to sowing.

Buntine 2012 Barley

Sow rate or Target density Not specified
Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Fertiliser Not specified
Herbicide Not specified
Insecticide Not specified
Soil amelioration Not specified
Tillage Not specified

Buntine 2012 Oats

Sow rate or Target density Not specified
Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Fertiliser Not specified
Herbicide Not specified
Insecticide Not specified
Soil amelioration Not specified
Tillage Not specified
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
Site Depth Type pH EC P K N A OC CAT
Buntine, WA 0 - 10cm Sand 6.20 216.00 0.64
Soil conditions
Trial site Soil texture
Buntine, WA Deep sand
Derived trial site soil information
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 Buntine WA
2012 114.9mm
2011 147.3mm
2010 115.2mm
2009 127.0mm
2008 144.9mm
2007 100.2mm
2006 104.1mm
2005 130.1mm
2004 125.2mm
2003 130.9mm
2002 87.6mm
2001 67.7mm
2000 105.5mm
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



Buntine WA 2012

Observed climate information

Rainfall avg ann (mm) 338mm
Rainfall trial total (mm) 287mm
Rainfall trial gsr (mm) 164mm

Derived climate information

Buntine WA


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: 06-08-2019 07:54am AEST