Researcher(s) |
Louise Barton |
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Year(s) | 2012 |
Contributor | SoilsWest |
Trial location(s) |
Buntine, WA
|
Related trials |
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 |
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Host research organisation |
Liebe Group |
Trial funding source | Australian Government DAF00004-04 |
Trial funding source | GRDC DAW00222 |
Related program |
Commonwealth Filling the Research Gap |
Acknowledgments |
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 |
Crop types | Oilseed: Canola Cereal (Grain): Barley Forage: Oats |
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Treatment type(s) |
|
Trial type | Experimental |
Trial design | Randomised,Replicated,Blocked |
Sow rate or Target density | 3 kg/ha Telfar |
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Sow date | 7 June 2012 |
Harvest date | 29 November 2012 |
Plot size | Not specified |
Plot replication | 3 |
Psuedoreplication | Not specified |
Fertiliser |
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. |
Herbicide |
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 |
Insecticide |
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. |
Sow rate or Target density | Not specified |
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Sow date | Not specified |
Harvest date | Not specified |
Plot size | Not specified |
Plot replication | Not specified |
Psuedoreplication | Not specified |
Fertiliser | Not specified |
Herbicide | Not specified |
Insecticide | Not specified |
Soil amelioration | Not specified |
Tillage | Not specified |
Sow rate or Target density | Not specified |
---|---|
Sow date | Not specified |
Harvest date | Not specified |
Plot size | Not specified |
Plot replication | Not specified |
Psuedoreplication | Not specified |
Fertiliser | Not specified |
Herbicide | Not specified |
Insecticide | Not specified |
Soil amelioration | Not specified |
Tillage | Not specified |
Rainfall avg ann (mm) | 338mm |
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Rainfall trial total (mm) | 287mm |
Rainfall trial gsr (mm) | 164mm |
SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
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.