Controlled traffic/permanent bed farming reduces GHG emissions. Jeff Tullberg

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 GraceQueensland University of Technology, Brisbane.

Australian controlled traffic (no-till) farming

Harvesting, Seeding, Spraying,

From same permanent traffic lanes

China Controlled Traffic Research

Harvesting, 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 inputs

Many characteristic shared with – Permanent Raised Bed (PRB) in Mexico and Asia – Permanent bed, reduced-till intensive cropping.

Impact?

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 water

Top 300mm

mm 29 47M 27 30W

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)

TComparison of wheeled and non-wheeled soil

Why?

Annual Tractor Wheel Impact in Zero Till

.

24 cm

4- Years CTF Non-Wheeled

Annually Wheeled (5t Tractor)

Black = Soil Solids, White = Air or Water (from D.McGarry )

Greenhouse Impact?

• Inputs • Fuel, Machinery• Herbicides• Fertilisers

• Outputs • Nitrous oxide & methane• Nitrate in runoff and drainage• Nitrate in eroded soil

}

}

Easily QuantifiedFor Known Systems

Highly Variable, Less Well-Understood

Greenhouse gas emissions (not Carbon)

Energy

Wasted Energy

In practise:Greenhouse Impact = Economic Impact

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?

Permanent Traffic Lane

(T.Lane)

Permanent Traffic Lane

(T.Lane)

Permanent Bed Non-Wheeled

(P.Bed)Permanent Bed +

1 Pre-seeding Wheeling (Rand)

Pilot trial, 2010 Wheat seeded + 80kg/ha N as anhydrous ammomia, interrow

4-year of 3m CTFheavy vertosol, disk

seeder, tine fertiliser. 3m

Emission Chambers

0 5 10 15 20 25 30 35 40 450

50

100

150

200

250

300

350

400N2O-N

ug.m-2.h-1T Lane

Rand

P Bed

Series7

Wheel Impact:N2O increased significantly on 3 occasions after rainCH4 increased significantly on 1 occasion after rain

Days after planting

Emissions

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

Cumulative Emissions Emissions (6 weeks post-seeding)

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 WUEindicating possibility of greater biomass and C input.

Needs investigation in different environments