Controlled traffic/permanent bedfarming 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.
Australian controlled traffic (no-till) farmingHarvesting, Seeding, Spraying,From same permanent traffic lanes
China Controlled Traffic ResearchHarvesting, Seeding, Spraying,From same permanent traffic lanes
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 inputsMany characteristic shared with – Permanent Raised Bed (PRB) in Mexico and Asia – Permanent bed, reduced-till intensive cropping. Impact?
TComparison of wheeled and non-wheeled soilParameter Units Australian Vertosol China, Loess Wheeled Non-wheeled Wheeled Non-wheeledWheel Load t/axle 4-5 1-2Rainfall ( 5year mean) mm/yr 907 (incl. irrigation) 558Runoff ( 5year mean) mm/yr 193 112L 32 18WInfiltration (80mm/h, 1h) mm/h 27 97L 12 41WAvailable Top mm 29 47M 27 30Wwater 300mmBulk density 1.36 1.28M 1.51 1.59WEarthworms/m2 # 40 108Fuel use, seeding l/ha 5.6 3.0T / /Grain yield( 5year mean) t/ha 3.70 4.05T 3.05 3.25WL Li et (2007); W Wang et al(2009): T Tullberg et al(2007); M McHugh et al(2009) Why?
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?
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
Soil Emissions – Nitrous Oxide, NO3 (+ Methane)Literature: N loss and emissions associated with waterloggingNO3emissions 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?
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)
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
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 1.00Wheeltrack emissions probably greater by a factor of 5.0 – 7.0
Conclusions1. 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