| Researcher(s) |
Diogenes L Antille Chris Bluett Jochen Eberhard Clemens Scheer Jeff N Tullberg |
|---|---|
| Year(s) | 2014 - 2016 |
| Contributor | Australian Controlled Traffic Farming Association Inc. |
| Trial location(s) |
Inverleigh, VIC
|
Soil compaction affects soil aeration and gas diffusivity, and thus has a major impact on the release of greenhouse gases (GHGs) from fertilised soils. Controlled traffic farming (CTF) systems reduce the area of compacted soil by confining all field traffic to permanent traffic lanes, and a pilot trial at one long-term CTF site provided evidence of reduced soil emissions. We investigated the effect of CTF on soil emissions of nitrous oxide (N2O) and methane (CH4) using replicate manual chamber measurements in 3 traffic treatments;namely:non-trafficked CTF beds, permanent CTF lanes,and a single traffic pass on CTF beds to simulate the random traffic tracks of non-controlled traffic farming. Emissions of N2O and CH 4 were monitored from these treatments in 15 crops over 3 years on 6 grain farms in Queensland, Victoria and Western Australia.
Thus, the major objective was to determine the emissions of N2O and CH4 from random trafficked and permanent traffic lane soil, relative to those from non-trafficked CTF beds. These emission ratios are referred to here as traffic impact factors.
This work has demonstrated that N2O emissions from trafficked soil were consistently and significantly greater (by an average factor of 2.2) than those from non-trafficked soil. At the same time, soil CH4 consumption was significantly increased in the CTF beds compared to random-trafficked or permanent traffic lanes, although overall CH4 fluxes were small. Permanent traffic lanes normally represent only 10%–15% of field area on controlled traffic farms, compared with ∼50% or more trafficked area on non-controlled traffic farms. Thus, the results indicate that adoption of controlled traffic should reduce soil emissions of C2O-e by 30%–50%, and this effect would be greater if N fertiliser could be excluded from permanent traffic lanes. The reduction in emissions also indicates that less N has been lost by denitrification, an effect which might be in the range of 3 – 20 kg/ha.
The work has demonstrated that CTF will reduce the GHG emissions from grain production, in addition to providing economic and other environmental benefits.
Mean results from low-intensity N2O and CH4 emission monitoring in 15 crops in the extensive dryland grain growing areas of Queensland, Victoria and Western Australia have demonstrated that:
1. Nitrous oxide emissions from random-trafficked soil are greater than those of neighbouring non-trafficked soil by an average factor of >2. Non-trafficked soil in these systems also absorb approximately 1.8 g ha−1 d−1 more methane than trafficked soil.
2. Controlled traffic farming reduces the proportionof field area affected by traffic, and might be expected to reduce the GWP of soilemissions of N2O and CH4 by 30%–50%.
3. Low-intensity monitoring is the basis for a first estimate of the quantitative impact of controlled traffic farming: a reduction in annual emissions from dryland grain farming by 90–150 kgha−1 CO2-e. If these estimates are correct, converting 50% of the 22 Mha of dryland grains in Australia to CTFcould reduce annual emissions from Australian cropping (currently 5.0 Mt CO2-e, Anon., 2015) by 0.6–1.7 Mt CO2-e.
4. Emission effects of CTF are likely to be much greater in irrigated production (e.g., cane, cotton, and horticulture) where N fertiliser inputs and soil moisture levels due to irrigation are greater and more frequent traffic accompanies the more intensive management.
5. Further work is required to: a) Refine and confirm the quantitative impact of CTF using high-intensity sampling accompanied by thorough monitoring of soil and environmental factors. b) Adjust and validate soil/plant models(e.g.APSIM, Keatingetal.,2003) to generalise and expand our understanding of traffic impact on N 2O emissions and denitrification losses in parallel with c) and d) below. c) Assess the emission impact of less heavily loaded field traffic (e.g. implement frame wheels running on permanent crop beds), and improved N fertiliser placement. d) Demonstrate and assess field traffic impacts on soil emissions from other cropping systems, particularly those of intensive agriculture, and the steps necessary to control traffic in these industries.
| Lead research organisation |
Australian Controlled Traffic Farming Association Inc. |
|---|---|
| Host research organisation | N/A |
| Trial funding source | AGAC AOTG2--0062 |
| Trial funding source | GRDC ACT00004 |
| Related program | N/A |
| Acknowledgments |
This project has been supported by the Australian Controlled Traffic Farming Association, through funding from the Australian Government Department of Agriculture and Water Resources, as part of its Carbon Farming Futures Action on the Ground Program (AOTGR2-62 Nitrous oxide emission reductions from controlled traffic farming). Additional support for the Swan Hill site was provided by Grains Research and Development Corporation project ACT 0004 “CTF in the Southern Low Rainfall Zone”. Dr A. Marchuk (Environmental Chemistry Laboratory, USQ) for processing and analysis of gas samples. Andrew Newall (Newag Consulting) for sampling near Horsham (Vic). Dr F. D'Emden and A. Sinnott (Precision Agronomics) for sampling near Esperance (W.A.). Grain growers R. McCreath and J. Piper (both of Felton, Qld.), R. Peel and J. Walter (Inverleigh, Vic.), G. Rethus (Horsham, Vic.), L.Bryan (Swan Hill, Vic), and M. Wandel (Esperance, W.A.), for allowing use of their gr |
| Other trial partners | Listed in acknowledgements |
| Crop type | Pasture: Mixed species |
|---|---|
| Treatment type(s) |
|
| Trial type | Experimental |
| Trial design | Replicated |
| Sowing machinery |
CTF fields always have heavily-trafficked permanent traffic lanes and non-trafficked beds, but for the purposes of this experiment an additional “random” wheeltrack was imposed on the permanent crop beds to mimic traffic impact in non-controlled (random) traffic farming. This was installed during the seeding operation, when growers were asked to make a single tractor and seeder unit pass along a 50 m length ofcrop bed, 0.8-1.0 m away from the permanent lanes, with all soil-engaging components lifted clear of the soil. This was carried out immediately before seeding the site normally, travelling on the permanent lanes, leaving two seeded 0.48–0.65 m wide “random” wheeltracks on the permanent beds. This layout was used on all sites with minor variations depending on grower equipment. It provided 2 sets of the 3 treatments with space for 4 replicate chambers (2 placed on each wheeltrack) with minimum additional soil/crop impact.& |
|---|---|
| Sow date | Not specified |
| Harvest date | Not specified |
| Plot size | Not specified |
| Plot replication | Not specified |
| Fertiliser |
Some fertiliser is applied at seeding, and N fertiliser top-dressing is broadcast as required. More site information, including fertiliser inputs and the number of years of CTF operation at each of the 15 sites can be found in the report. |
| Soil amelioration |
GHG fluxes were measured using the closed chamber technique. This method uses a gastight chamber, which encloses a fixed surface area of soil for a given time interval.Chambers of 2 types were used during this work namely cylindrical chambers and rectangular chambers. The 12 chamber bases were positioned as soon as possible after seeding, with 4 replicate chambers in each treatment, where the treatments represented permanent non-trafficked CTF beds, permanent CTF traffic lanes, and random-trafficked soil. Only one chamber type was used within any one site, and chamber positioning was consistent with respect to crop rows across all planted treatments, to ensure similar relationships with seed and fertiliser bands. Sampling was carried out by local agricultural consultants. Tthe protocol requested weekly sampling for 6 weeks following seeding with 2 more weekly samplings carried out after fertiliser top-dressing, fortnightly at other tim |
| Sowing machinery | Not specified |
|---|---|
| Sow date | Not specified |
| Harvest date | Not specified |
| Plot size | Not specified |
| Plot replication | Not specified |
| Fertiliser | Not specified |
| Soil amelioration | Not specified |
| Sowing machinery | Not specified |
|---|---|
| Sow date | Not specified |
| Harvest date | Not specified |
| Plot size | Not specified |
| Plot replication | Not specified |
| Fertiliser | Not specified |
| Soil amelioration |
Soil compaction affects soil aeration and gas diffusivity, and thus has a major impact on the release of greenhouse gases (GHGs) from fertilised soils. Controlled traffic farming (CTF) systems reduce the area of compacted soil by confining all field traffic to permanent traffic lanes, and a pilot trial at one long-term CTF site provided evidence of reduced soil emissions. We investigated the effect of CTF on soil emissions of nitrous oxide (N2O) and methane (CH4) using replicate manual chamber measurements in 3 traffic treatments;namely:non-trafficked CTF beds, permanent CTF lanes,and a single traffic pass on CTF beds to simulate the random traffic tracks of non-controlled traffic farming. Emissions of N2O and CH 4 were monitored from these treatments in 15 crops over 3 years on 6 grain farms in Queensland, Victoria and Western Australia. This work has demonstrated that N2O emissions from trafficked soil were consistently and significantly greater ( |
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.
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