CONSERVATION AGRICULTURE, EMISSIONS AND RESILIENCE: OPPORTUNITIES AND DANGERS J. N. Tullberg, CTF Solutions, Brisbane, Australia.

Summary Conservation 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 } } Easily Quantified For Known Systems. Substantial System Effects Highly Variable, Poorly Understood. Very Large System Effects, Systems and Effects

Generic Systems Stubble mulching, 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 Permanent Raised Bed Systems: Mexico Gansu, 2 Mg Axles (similar effects in top 10cm )

Spreadsheet Assessment --Basis Fuel energy CO 2 Herbicide energy CO 2 Fertiliser energy CO 2 Soil emissions. N 2 O, CH 4 CO 2 -e =  {CO 2 + (300 x N 2 O) + (23 x CH 4 ) 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 Zero Tillage CTF Tullberg J.N. (2000) Traffic Effects on Tillage Energy. Journal of Agricultural Engineering Research 75(4) 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 Massive Structure 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 Zero Tillage CTF Tullberg J.N., Yule D.F. and McGarry D. (2007) Controlled traffic farming— From research to adoption in Australia. Soil & Tillage Research –281 Side-by-side experiments don’t capture system effects.

System Operations SystemChiselCultivateSpraySeedFertilizeHarvest Stubble Mulch Zero Tillage CTF003*11**1 *Improved timeliness increases herbicide effectiveness. ** In-crop fertiliser more common in CTF DPIF (2008) Selection and matching of tractors and implements. and matching of tractors and implements

System Fuel Requirements OperationChisel L/ha Cultivate L/ha Spray L/ha Seed L/ha Fertilize L/ha Harvest L/ha Total L/ha CO 2 kg/ha Stubble Mulch Zero Till CTF * DPIF (2008) Selection and matching of tractors and implements. and matching of tractors and implements 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 –154 Peter Bradley, P (2008) Contract Harvesting and Controlled Traffic Expenses and Costs. 6th Australian Controlled Traffic Farming Conference,

System Fuel Requirements OperationChisel L/ha Cultivate L/ha Spray L/ha Seed L/ha Fertilize L/ha Harvest L/ha Total L/ha CO 2 kg/ha Stubble Mulch Zero Till CTF * DPIF (2008) Selection and matching of tractors and implements. and matching of tractors and implements 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 –154 Peter Bradley, P (2008) Contract Harvesting and Controlled Traffic Expenses and Costs. 6th Australian Controlled Traffic Farming Conference,

Herbicides* Commer cial Product Herbicide Mean Freq’cy Label rate Energy Fuel L/ha CO 2 kg/ha /crop kg/ha MJ/kgMJ/ha 2,4-D Amine 2,4-D Atrazine SpraySeedDiquat/ Paraquat Roundup CTGlyph -osate E MJ/haFuel L/ha CO 2 /ha Herbicide CO 2 So mean impact / spray = StubbleMulch 10.7 Zero Till 42.9 CTF 32.2 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.

Fertiliser** Nitrogen 75.6 MJ/kg Phosphate 9.5 MJ/kg Potassium 9.9 MJ/kg Total Energy CO 2 kg/ha System kg/haMJ/hakg/haMJ/hakg/haMJ/ha (from gas) Stubble Mulch Zero Till CTF40* *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. *Ruwolt, R. (2008). CTF/No till Farming 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. Prewb Effects of Waterlogging at Different Stages of Development on the Growth and Yield of Winter Wheat J. Sci. Food Agric. 1980, 31, **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* SystemNO 2 - kg/ha/day (during early growth) CO 2 Equivalent - kg/ha/day Nitrous Oxide Methane Nitrous oxide MethaneNitrous oxide Methane System CO 2 E kg/ha/day Random Traffic Stubble Mulch Seasonal CTF CTF Zero Till** * 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: /j.still ** 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 –100)

Soil Emissions -Total NO2 ProductionMethane ProductionTotal System Days*CO 2 E kg/haDays**CO 2 E kg/ha Stubble Mulch Zero Till CTF * 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 days. ** Methane absorption/emission occurs over a wider range of soil conditions: Assumption – 150 days.

Total System Emissions – CO 2 -e (Good Evidence) (Speculative) Soil Emissions Grand Total Emissions Diesel Fuel Herb -icide Fertil -iserTotal System kg/ha Stubble Mulch Zero Till CTF 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 Losses Pollution & 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 % less from CTF zero till, compared with random traffic zero tillage or stubble mulch systems. Soil emissions from CTF zero till systems are % 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