CONSERVATION AGRICULTURE, EMISSIONS AND RESILIENCE:

OPPORTUNITIES AND DANGERS

J. N. Tullberg, CTF Solutions,Brisbane, Australia.

jeff@ctfsolutions.com.au

SummaryConservation agriculture has big environmental benefits, but is it climate-friendly?

Factors:

•Soil carbon • (CA better, but still not always positive)

•Energy• (CA better on fuel, often not better overall)

•Soil emissions • (CA often negative from nitrous oxide and methane)

Answer: not always. System & Climate Dependent.

Emission Mechanisms

• Inputs: (energy)• Fuel, Machinery• Herbicides• Fertilisers

• Outputs: (losses) • Gaseous nitrous oxide & methane• Nitrate in runoff and drainage• Nitrate in eroded soil

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Easily QuantifiedFor Known Systems.Substantial System Effects

Highly Variable, Poorly Understood.Very LargeSystem Effects,

Systems and Effects

Generic Systems• Stubble mulching, 1 - 3 minimum-inversion tine or sweep tillage

operations, and 1 – 3 herbicide weed control operations per crop. (most common).

Tilled, Random Wheels

• Zero tillage, herbicide weed control, soil disturbance at seeding, but occasional chisel tillage after wet harvests. (less common).

Minimum Tillage, Random Wheels

• Controlled traffic farming (CTF), herbicide weed control, minimal soil disturbance at seeding, all heavy wheels on permanent traffic lanes oriented for surface drainage, opportunity cropping. (least common, growing).

Minimum Tillage, Precise Wheels

Random Traffic Wheeling?

>20% at Harvest>20% at Seeding~ 5% at Spraying~ 5% Logistics

50% Field Area Wheeled/Crop -- In Zero Tillage

Wheel Effect Lasts >2 years at 20cm in cracking clay

Track Width 3m Tyre Width 0.5m

CTF, Australia

Header Width 9m,12m.

Track Width 3m Tyre Width 0.5m

2cm GPS Autosteer

20 Mg Axle Harvesters

• CTF Planting Shanxi

CTF Shanxi, China

1.2m

1.2m

Permanent Raised Bed Systems:

MexicoGansu,

2 Mg Axles (similar effects in top 10cm )

Spreadsheet Assessment --Basis• Fuel energy CO2

• Herbicide energy CO2

• Fertiliser energy CO2

• Soil emissions. N2O, CH4

CO2-e = {CO2 + (300 x N2O) + (23 x CH4)

• Soil carbon, • Runoff, drainage water

Context: water limited, dryland grain production………

….. but probably relevant to most cropping systems.

} Comment Only

Quantified as

Relative Performance, Generic Systems

Seeding Power

Infiltration rate

(extreme event)

Soil biota (earthworm)

PAWC (top

300mm)

Grain yield (9

crop mean)

Stubble mulch

100 100 100 100 100

Zero Tillage

100 170 400 120 105

CTF 50 260 1100 185 115

Tullberg J.N. (2000) Traffic Effects on Tillage Energy. Journal of Agricultural Engineering Research 75(4).375-382.

What happens to 50% wasted power?

Comparing just the Seeding Operations

Random Traffic Effects – Zero Tillage Plots

.

24 cm

Non-Wheeled

4- Years CTF

Profiles – White = Soil Solids Black = Air or Water

Impact of Tractive

Power Loss.

Coarse Aggregates

MassiveStructure

Wheeled

(4t Axle Once/year)

Relative Performance, Generic Systems

Seeding Power

Infiltration rate

(extreme event)

Soil biota (earthworms)

PAWC (top

300mm)

Grain yield (9

crop mean)

Stubble mulch

100 100 100 100 100

Zero Tillage

100 170 400 120 105

CTF 50 260 1100 185 115

Tullberg J.N., Yule D.F. and McGarry D. (2007) Controlled traffic farming— From research to adoption in Australia. Soil & Tillage Research 97 272–281

Side-by-side experiments don’t capture system effects.

System OperationsSystem Chisel Cultivate Spray Seed Fertilize Harvest

Stubble Mulch

1 2 1 1 0 1

Zero Tillage

0.33 0 4 1 0 1

CTF 0 0 3* 1 1** 1

*Improved timeliness increases herbicide effectiveness.** In-crop fertiliser more common in CTF

DPIF (2008) Selection and matching of tractors and implements. http://www2.dpi.qld.gov.au/thematiclists/9155.html

System Fuel RequirementsOperation Chisel

L/ha Cultivate

L/haSprayL/ha

SeedL/ha

FertilizeL/ha

HarvestL/ha

Total L/ha

CO2

kg/haStubble Mulch

9.8 6 1.4 5.0 0 8 36.2 105

Zero Till 9.8 0 1.4 5.0 0 8 21.8 63CTF 0 0 0.7 2.5 1 6* 12.1 35

DPIF (2008) Selection and matching of tractors and implements. http://www2.dpi.qld.gov.au/thematiclists/9155.html

G.F. Botta, O. Pozzolo, M. Bomben, H. Rosatto, D. Rivero, M. Ressia, M. Tourn, E. Soza, J. Vazquez (2007) Traffic alternatives for harvesting soybean (Glycine max L.) Effect on yields and soil under a direct sowing system Soil & Tillage Research 96 145–154

Peter Bradley, P (2008) Contract Harvesting and Controlled Traffic Expenses andCosts. 6th Australian Controlled Traffic Farming Conference, 2008 32

System Fuel RequirementsOperation Chisel

L/ha Cultivate

L/haSprayL/ha

SeedL/ha

FertilizeL/ha

HarvestL/ha

Total L/ha

CO2

kg/haStubble Mulch

9.8 6 1.4 5 0 8 36.2 105

Zero Till 9.8 0 1.4 5 0 8 21.8 63CTF 0 0 0.7 3 1 6* 12.1 35

DPIF (2008) Selection and matching of tractors and implements. http://www2.dpi.qld.gov.au/thematiclists/9155.html

G.F. Botta, O. Pozzolo, M. Bomben, H. Rosatto, D. Rivero, M. Ressia, M. Tourn, E. Soza, J. Vazquez (2007) Traffic alternatives for harvesting soybean (Glycine max L.) Effect on yields and soil under a direct sowing system Soil & Tillage Research 96 145–154

Peter Bradley, P (2008) Contract Harvesting and Controlled Traffic Expenses andCosts. 6th Australian Controlled Traffic Farming Conference, 2008 32

Herbicides*Commer cial

ProductHerbicide Mean

Freq’cyLabel rate

Energy  

Fuel L/ha

CO2

kg/ha/cropkg/ha MJ/kg MJ/ha  

2,4-D Amine 2,4-D 1 0.5 98 49   1.23 4Atrazine Atrazine 2 0.5 190 95   2.38 7SpraySeed Diquat/

Paraquat 10.25 430 107.5   2.69 8

Roundup CT Glyph -osate 3

0.45 511 229.95   5.75 17

                 

       E MJ/ha Fuel L/ha  CO2/ha Herbicide CO2

So mean impact / spray = 146 3.95 10.7 StubbleMulch 10.7        Zero Till 42.9 CTF 32.2Zentner,R.P., Lafond, G.P.,Derksen, D.A.,Nagy,C.N., Wall,D.D., May, W.E. (2004) Effects of Tillage Method and Crop Rotation on Non-Renewable Energy Use Efficiency in the Canadian Prairies. Soil and Tillage Research 77; 125 – 136.

Fertiliser**  Nitrogen

75.6 MJ/kgPhosphate 9.5 MJ/kg

Potassium 9.9 MJ/kg

Total Energy

CO2

kg/haSystem

kg/ha MJ/ha kg/ha MJ/ha kg/ha MJ/ha (from gas)Stubble Mulch 45 3402 5 47.5 8 79.2 3528.7 211.7Zero Till 45 3402 5 47.5 8 79.2 3528.7 211.7CTF 40* 3024 5 47.5 8 79.2 3150.7 189.0

*Lefroy, T.(2007) Soil biology - Trials push beyond soil quick fix. Ground Cover Issue 68 - May - June 2007*Des McGarry 2006 Soil compaction in cropping land . Natural Resources and Water. www.nrw.qld.gov.au/factsheets/pdf/land/l84.pdf*Ruwolt, R. (2008). CTF/No till Farming 2008 -- What We Learned? 6th Australian controlled traffic conference, Dubbo NSW. Proceedings, p.50.*Robert Q, Cannell, Robert K. Belford, Kenneth Gales,Colin W. Dennisa Robert D. PrewbEffects of Waterlogging at Different Stages of Development on the Growth and Yield of Winter Wheat J. Sci. Food Agric. 1980, 31, 117-132**Zentner,R.P., Lafond, G.P.,Derksen, D.A.,Nagy,C.N., Wall,D.D., May, W.E. (2004) Effects of Tillage Method and Crop Rotation on Non-Renewable Energy Use Efficiency in the Canadian Prairies. Soil and Tillage Research 77; 125 – 136.

Soil Emissions*System NO2 - kg/ha/day

(during early growth)

CO2 Equivalent - kg/ha/day

NitrousOxide

Methane

  Nitrous oxide

Methane Nitrous oxide

Methane  System CO2E kg/ha/day

CO2E kg/ha/day

Random Traffic

0.068 0.00075 21.08 0.01725  Stubble Mulch

21.1 0.017

Seasonal CTF

0.047 -0.0049 14.57 -0.1127  CTF 14.6 -0.113

  Zero Till** 27.59 0.1472

*Vermeulen, G.D., Mosquera, J. (2008). Soil, crop and emission responses to seasonal-controlled traffic in organic vegetable farming on loam soil. In press, Soil Tillage Res., doi:10.1016/j.still.2008.08.008

** Assumption. Increment between zero till and CTF will be the same as that between stubble mulch and CTF (based on drainage/infiltration conditions in CTF, stubble mulch, and zero till, determining the occurrence of near-saturated conditions. (see Rochette, P. (2008) No-till only increases N2O emissions in poorly-aerated soils. Soil & Tillage Research 101 97–100)

Soil Emissions -Total  NO2 Production Methane Production TotalSystem Days* CO2E kg/ha Days** CO2E kg/ha CO2E kg/haStubble Mulch 30 632.4 150 2.59 635Zero Till 30 827.7 150 22.08 850CTF 30 437.1 150 -16.91 420

* Nitrous oxide production occurs when excess nitrate is available at high levels of water-filled porosity. This will normally occur over a relatively short period between fertilizing and crop assimilation: Assumption -- 30 days.

** Methane absorption/emission occurs over a wider range of soil conditions: Assumption – 150 days.

Total System Emissions – CO2-e

(Good Evidence)

(Speculative)

Soil Emissions

Grand Total

Emissions  Diesel

FuelHerb-icide

Fertil-iser Total

System kg/ha kg/ha kg/ha kg/ha kg/ha kg/ha

Stubble Mulch

105 10.7 212 327

635 962

Zero Till 63 42.9 212 318

850 1168

CTF 35 32.2 189 256

420 677

Zero Tillage alone is not the answer.

We must also stop Random Wheeling

Soil Carbon Sequestration

Difficult/Slow at < 400mm/yr rain, but optimised in CTF by:

• Maximum Biomass Production (High WUE).

• Maximum Standing Residue (Min Wheels, )

• Minimum Soil Disturbance (Zero Till)

Advantages of Precise Interrow Seeding

Runoff & Drainage LossesPollution & Nutrient Loss Minimized in CTF by:

• Max Infiltration (Residue, No Compaction)

• Max Available Water Capacity (Soil Health, SOM)

• Opportunity Cropping ( Timeliness, Precision)

Relay Cropping

CONCLUSIONS• Input-related emissions (from fuel, herbicides and fertiliser) are

demonstrably 20- 40% less from CTF zero till, compared with random traffic zero tillage or stubble mulch systems.

• Soil emissions from CTF zero till systems are 30- 70% less than those

from random traffic zero till. Emissions from stubble mulch tillage are substantially less than those from random traffic zero till.

• Major mechanisms of random traffic effects on emissions include

direct compaction effects on tillage energy, fertiliser efficiency and soil porosity, and indirect effects via soil health, and timeliness.

• Biomass production is improved in CTF by minimising runoff, drainage (and pollution) with minimum soil disturbance to optimise soil carbon balance.

Synythesis

Major , Global Challenges:

• Poor Energy Efficiency• Poor Fertilizer Efficiency• Poor Water Efficiency }

Its not difficult to fix, if we try

Thank You

All guarantee poor carbon balance

All Lose >50% under Random Wheel Traffic

Thank You

• Acarina (mites)

• Collembola (springtails)

• Free-living nematode

• Plant parasitic nematode

Earthworms

Aeration, Soil Strength, SOM??

Uncontrolled Field Traffic

After the flood -you can see every wheel pass