Controlled traffic/permanent bed farming reduces greenhouse gas emissions by using permanent traffic lanes that minimize soil compaction compared to conventional tillage. A pilot study found nitrous oxide emissions were 5-7 times higher in permanent traffic lanes compared to non-wheeled permanent beds. As controlled traffic farming only wheels 10-20% of the area while conventional farming wheels 50% or more, controlled traffic farming is expected to reduce soil emissions by over 50%. Improved soil health and water use efficiency with controlled traffic farming may also increase carbon input into soils. Further research is still needed across different environments.

1. Controlled traffic/permanent bed
farming reduces GHG emissions.
Jeff Tullberg , Jack McHugh, Boorzoo Ghareel Khabbaz,
University of Southern Queensland, Toowoomba and CTF Solutions, Brisbane.
Clemens Scheer, Peter Grace
Queensland University of Technology, Brisbane.

2. Australian controlled
traffic (no-till) farming
Harvesting, Seeding, Spraying,
From same permanent traffic lanes

3. China Controlled
Traffic Research
Harvesting, Seeding, Spraying,
From same permanent traffic lanes

4. Controlled Traffic Farming (CTF)
• Permanent traffic lanes for all heavy wheels.
Permanent no-till crop beds.
• Layouts designed for drainage and logistics.
Timeliness, precision, better soil and agronomy*
*opportunity crops, optimised inputs
Many characteristic shared with
– Permanent Raised Bed (PRB) in Mexico and Asia
– Permanent bed, reduced-till intensive cropping.
Impact?

5. TComparison of wheeled and non-wheeled soil
Parameter Units Australian Vertosol China, Loess
Wheeled Non-wheeled Wheeled Non-wheeled
Wheel Load t/axle 4-5 1-2
Rainfall ( 5year mean) mm/yr 907 (incl. irrigation) 558
Runoff ( 5year mean) mm/yr 193 112L 32 18W
Infiltration (80mm/h, 1h) mm/h 27 97L 12 41W
Available Top mm 29 47M 27 30W
water 300mm
Bulk density 1.36 1.28M 1.51 1.59W
Earthworms/m2 # 40 108
Fuel use, seeding l/ha 5.6 3.0T / /
Grain yield( 5year mean) t/ha 3.70 4.05T 3.05 3.25W
L Li et (2007); W Wang et al(2009): T Tullberg et al(2007); M McHugh et al(2009)
Why?

6. Annual Tractor Wheel Impact in Zero Till
Black = Soil Solids, White = Air or Water (from D.McGarry )
24 cm
4- Years CTF Annually Wheeled
Non-Wheeled (5t Tractor)
.
Greenhouse Impact?

7. Greenhouse gas emissions (not Carbon)
• Inputs
• Fuel, Machinery
• Herbicides
• Fertilisers
} Easily Quantified
For Known Systems
Energy
• Outputs
• Nitrous oxide & methane
• Nitrate in runoff and drainage
• Nitrate in eroded soil } Highly Variable,
Less Well-Understood
Wasted Energy
In practise:
Greenhouse Impact = Economic Impact

8. Soil Emissions – Nitrous Oxide, NO3 (+ Methane)
Literature: N loss and emissions associated with waterlogging
NO3emissions occur when: Water- filled porosity <75%, >65%.,
Nitrate +C present in surface 10 cm.
Management Impact ?
Till v. no-till: less NO3 emissions in well-drained soils. (Rochette 2009)
more NO3 emissions in poorly drained soils.
(measurements rarely taken in wheel tracks)
Wheel effect: wheeled soil emissions 5 x non wheeled (Russer 1998)
(potato fields) wheeled soil emissions 5 x non wheeled (Thomas 2003)
Common thread– wheel effects?

9. Pilot trial, 2010 Wheat seeded + 80kg/ha N
as anhydrous ammomia, interrow
4-year of 3m CTF
heavy vertosol, disk
seeder, tine fertiliser.
3m
Emission Chambers
Permanent
Traffic Lane
(T.Lane)
Permanent Bed
Non-Wheeled
Permanent (P.Bed)
Permanent Bed +
Traffic Lane 1 Pre-seeding Wheeling
(T.Lane) (Rand)

10. Emissions
N2O-N T Lane
400 ug.m-2.h-1 Rand
350 P Bed
300
250
200
150
100
50
0
0 10 20 30 40 50
Days after planting
Wheel Impact:
N2O increased significantly on 3 occasions after rain
CH4 increased significantly on 1 occasion after rain

11. Cumulative Emissions Emissions (6 weeks post-seeding)
kg CO2-e/ha
Source T Lane Rand P Bed
kg kg kg
N2O 324.6 369.5 58.2
CH4 0.33 0.41 -0.43
Total 324.6 369.5 58.2
Ratio 5.57 6.35 1.00
Wheeltrack emissions probably greater by a factor of 5.0 – 7.0

12. Conclusions
1. Pilot trial confirms the literature:
wheel track emissions 5-7 times greater than bed emissions.
2. Permanent traffic lanes in CTF occupy 10– 20% area.
but minimum of 50% area is wheeled in non—CTF.
3. This suggests that CTF should reduce soil emissions by >50%
possibly more with precise, split N application.
plus a substantial impact on input-related emissions.
4. Improved agronomy, soil health and precision also increase WUE
indicating possibility of greater biomass and C input.
Needs investigation in different environments