Sense and nonsense in Conservation Agriculture:     principles, pragmatism and productivity......           John Kirkegaar...
Principles - Conservation Agriculture (FAO)       ● Continuous minimum mechanical soil disturbance       ● Permanent soil ...
Australian environment, soils and system   Dry (300-500mm), infertile soils, unsubsidised agriculture                     ...
Farming system evolution      ● Up to 1980s              ley pastures grass/annual legumes (merino sheep for wool)        ...
Australian national wheat yield trends                  2.5                                                               ...
No-till adoption and use in Australia                     100                                             Extent of Use (2...
Precision agriculture - building on CAControlled traffic (CT)                          Variable rate technology (VRT)
Pragmatic adoption of principlesPrinciple 1. Minimum soil disturbance      ● No-till adopters cultivate 24% crop area     ...
Principle 1 – Minimum soil disturbance   High adoption, but flexible approach< 5% practice multiple cultivation pre-sowing...
Strategic tillage    Infrequent tillage in an (otherwise) “No-till” system    Does it cause irreparable soil damage?      ...
Strategic tillage - integrated weed management  Multiple herbicide resistant annual ryegrass (L. rigidum)  189 cases glyph...
New threat - resistant weeds in summer fallow  Current Glyphosate-resistant weeds in summer fallowConyza         Echinochl...
Strategic tillage - disease and biological constraints                             Intact soil cores from field  Rhizocton...
Inhibitory Pseudomonas on root tips in no-till soil                                                          Pseudomonas  ...
No-till root environment....not all good!                                Pore in no-till soil                             ...
Further benefits from root-soil biology research      Understanding                                      Yield constraints...
Principle 2 - Stubble retention Adoption rates are high  Cutting height , straw spreaders, wider rows, inter-row sowing  d...
CIMMYT:         30% retained = 100% retainedLong-term wheat yields on permanent beds (1993-2006)                          ...
Principle 3 – Diversity (pastures)    Managing livestock (and pastures) in CA systems  Integrate          Segregate       ...
Impact of livestock in CA systems            ● Surprisingly little data for southern Australia            ● Literature rev...
Dual-purpose crops – graze and grain ● Cereal and canola crops grazed without yield penalty ● Increase flexibility, profit...
Future - precision animal management....  ● Efficient, safe grazing in larger crop paddocks                “Virtual” fence...
Principle 3 – Diversity (broad-leaf crops)Intensive cereals dominate (64-80%)Why cereals?     easy to manage and market   ...
Inter-row sowing in CA systems                      Inter-row                        On-row                               ...
CA Systems - the carbon conundrum.....          Pastures build soil organic carbon (SOC)          CA slows SOC decline, bu...
Nutrients and C sequestration - incubation study                           Soil + stubble + supplementary nutrients       ...
CA systems - energy efficiency?Time, labour, fuel efficiencies undisputed (on-farm)Overall energy efficiency (grain yield ...
CA systems – component interactions              Baseline Scenario (Kerang, Victorian Mallee)1980s - Burn/cultivate, graze...
Summary of key messages  CA principles make sense - adoption is high Australian adoption is pragmatic (in system context) ...
CSIRO Plant IndustryJohn KirkegaardPhone: 02 62465080Email: john.kirkegaard@csiro.auThank youContact UsPhone: 1300 363 400...
Strategic tillage for multiple constraints                   Water-repellent sandy topsoil                   Herbicide res...
Strategic inversion tillage (1 year in 10)                                Plough ($70/ha)      Herbicides ($70/ha)        ...
3. Improving productivity of modern, no-till farming             Adoption is driven by         Erosion control, water cons...
Impact of season on response to no-till                                                                                   ...
Biological constraints in Retain - DD        Yellow leaf spot                                       RhizoctoniaInhibitory ...
Wheat productivity improvements ??                Yield differences (t/ha)      State            No-till vs Cult     Retai...
Adoption of No-till
CSIRO long-term study, Harden NSW                  (commenced 1990)  •   Increased earthworms  •   Higher microbial biomas...
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Sense and nonsense in CA: principles, pragmatism and productivity..... John Kirkegaard

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Sense and nonsense in CA: principles, pragmatism and productivity..... John Kirkegaard

  1. 1. Sense and nonsense in Conservation Agriculture: principles, pragmatism and productivity...... John KirkegaardMark Conyers, James Hunt, Clive Kirkby Michelle Watt, Greg Rebetzke
  2. 2. Principles - Conservation Agriculture (FAO) ● Continuous minimum mechanical soil disturbance ● Permanent soil cover (crop or mulch) ● Diversification of crop species in sequence/association
  3. 3. Australian environment, soils and system Dry (300-500mm), infertile soils, unsubsidised agriculture 120 0 CLERMONT 120 120 0 DALBY 120 Mixed farms (2000 ha) 0 CONDOBOLIN 0 1 crop/yr (May-Nov) 120 GERALDTON 120 Mean yield 2 - 3 t/ha 0 MOOMBOOLDOOL 120 0 MERREDIN 0 120 WAGGA WAGGA 120 120 0 0 0 ESPERANCE ROSEWORTHY HORSHAM
  4. 4. Farming system evolution ● Up to 1980s ley pastures grass/annual legumes (merino sheep for wool) cereals (wheat and barley) Pasture Wheat Barley● Since 1990 - Intensification of cropping fewer , larger farms increased crop area per farm (3.6% pa) less pasture, fewer sheep more crop diversity Pasture Canola Wheat Wheat Lupin Wheat
  5. 5. Australian national wheat yield trends 2.5 herbicides, N 1.1% pa break crops semi-dwarf wheat 2.0 Break crops & nitrogen Millenium drought legume pasture Phosphorus & Yield (t ha-1) mechanisation improved pasture 1.5 Fallowing, PFallowing & fertiliser mechanisation Organic cultivars new 1.0 farming 0.5 CA 0.0 1860 1880 1900 1920 1940 1960 1980 2000Angus (2009); Fischer (2009)
  6. 6. No-till adoption and use in Australia 100 Extent of Use (2009) WA, QLD 62 - 92% use No-till% no-till adoption 80 73 - 96% crop area 60 40 Mallee 20 0 1975 1980 1985 1990 1995 2000 2005 2010 YearGRDC 2010; Llewellyn et al 2011
  7. 7. Precision agriculture - building on CAControlled traffic (CT) Variable rate technology (VRT)
  8. 8. Pragmatic adoption of principlesPrinciple 1. Minimum soil disturbance ● No-till adopters cultivate 24% crop area ● 88% use narrow tines, not discsPrinciple 2. Permanent soil cover ● Crop residues often reduced (graze, bale, burn)Principle 3. Diversity in sequence ● integrating livestock and crops ● Intensive cereals (64 - 80% cereal)
  9. 9. Principle 1 – Minimum soil disturbance High adoption, but flexible approach< 5% practice multiple cultivation pre-sowingNo-till adopters use cultivation on 24% area88% use narrow points only (rather than discs)Discs used to sow ~30% cropped area(GRDC 2010; Llewellyn et al 2011)
  10. 10. Strategic tillage Infrequent tillage in an (otherwise) “No-till” system Does it cause irreparable soil damage? Case specific, but evidence is contested Strategic tillage can resolve some issues Weed, disease management Lime incorporation - 23M ha acid subsoils Subsoil amelioration Is some soil disturbance needed?
  11. 11. Strategic tillage - integrated weed management Multiple herbicide resistant annual ryegrass (L. rigidum) 189 cases glyphosate-resistance (50% no-till, continuous crop) Tillage has a role in IWM approach (Preston 2010) Resistant populations of annual ryegrass Harrington seed destructor
  12. 12. New threat - resistant weeds in summer fallow Current Glyphosate-resistant weeds in summer fallowConyza Echinochloa Urochloa Chloris Sonchus (at risk) No grazing (seed set control) No cultivation or burningFactors influencing Less disturbance (disc seeders)evolution under CA Wide rows (light for germination) No crop competition (summer fallow) 3-4 herbicide applications/yr
  13. 13. Strategic tillage - disease and biological constraints Intact soil cores from field Rhizoctonia solani No-till Cultivate No-till Fumigate (Simpfendorfer et al 2002)Cultivate No-till
  14. 14. Inhibitory Pseudomonas on root tips in no-till soil Pseudomonas per mm root (x 103) 12 8 4 Cultivated soil No- till soil (Fast growing roots) (Slow growing roots) 0 Fast growing Slow growing(Watt et al 2005, 2006) roots Roots
  15. 15. No-till root environment....not all good! Pore in no-till soil Live wheat crop roots Dead roots from preceding crop Hard soil – no roots 5 mm(Watt et al., 2005; ME McCully, images)
  16. 16. Further benefits from root-soil biology research Understanding Yield constraints may remain ● Varietal responses? ● Interactions of… new root genetics precision placement novel inputs (formulations)Lab Tilled No-till Farming systems Further efficiency and productivity gains
  17. 17. Principle 2 - Stubble retention Adoption rates are high Cutting height , straw spreaders, wider rows, inter-row sowing disc openers, improved herbicides, seed collection, seed destruction High rainfall mixed farms (heavy cereal residues > 6t/ha) less erosion risk high in-crop rainfall wide rows reduce yield weed, pest, disease issues pastures build soil C alternate use for residueMakes sense to manage to thresholds
  18. 18. CIMMYT: 30% retained = 100% retainedLong-term wheat yields on permanent beds (1993-2006) 100% retained = 30% retained None retained (burnt) Govaerts et al (2005)
  19. 19. Principle 3 – Diversity (pastures) Managing livestock (and pastures) in CA systems Integrate Segregate Eliminate Diverse Efficient (time/labour)Soil damage? Pasture benefits lost
  20. 20. Impact of livestock in CA systems ● Surprisingly little data for southern Australia ● Literature review (Bell et al 2011) ● Field experiments (4 sites since 2008) Outcomes Soil physical damage shallow and transient Removal of cover more important Water balance impacts season-dependant Effects on yield are rare Sheep mouths do more damage than hooves James Hunt , Thursday 9.35, pg 382
  21. 21. Dual-purpose crops – graze and grain ● Cereal and canola crops grazed without yield penalty ● Increase flexibility, profitability and reduce risk ● Increase animal and crop production from mixed farms
  22. 22. Future - precision animal management.... ● Efficient, safe grazing in larger crop paddocks “Virtual” fences ● zonal crop and stubble grazing ● livestock „sweeping‟ to achieve cover targets ● patch weed control
  23. 23. Principle 3 – Diversity (broad-leaf crops)Intensive cereals dominate (64-80%)Why cereals? easy to manage and market lower risk (cost and reliable performance) high residues for cover/grazingNew technology helps disease resistance, soil/seed fungicides, soil DNA testing precision inter-row sowing and residue management new herbicide options
  24. 24. Inter-row sowing in CA systems Inter-row On-row Take-all 18% Infection 50% Large stubble load● Cereal on cereal 6-9% yield benefit● Canola on cereal (Matt McCallum 2008)
  25. 25. CA Systems - the carbon conundrum..... Pastures build soil organic carbon (SOC) CA slows SOC decline, but rarely builds (slow) Why? Stable organic matter (humus) has a constant ratio of C:N:P:S 1000 kg C requires 83 kg N; 20 kg P; 14 kg S Nutrients (not C) might limit humus formation(Kirkby et al. Geoderma 2011)
  26. 26. Nutrients and C sequestration - incubation study Soil + stubble + supplementary nutrients Leeton 3.0 Laboratorystubble Soil + incubation study (Leeton soil) error bars are SE 10 t/ha wheat straw 2.5 + nutrients NPSCarbon (%) Carbon % 2.0 10 t/ha wheat straw 1.5 0 1 2 3 4 5 6 7 Incubation cycle Repeated addition of 10 t/ha wheat straw (3 monthly) (Clive Kirkby, Poster 122, pg 538)
  27. 27. CA systems - energy efficiency?Time, labour, fuel efficiencies undisputed (on-farm)Overall energy efficiency (grain yield per unit energy input) Conv. 173 kg GJ-1 Cereal-legume 360 kg GJ-1 No-till 177 kg GJ-1 Cereal monoculture 137 kg GJ-1Impact on GHG emissions (chemicals substitute for tillage) Chemical use 80 kg CO2e/ha Tillage 97 kg CO2e/ha (Maraseni & Cockfield 2011)
  28. 28. CA systems – component interactions Baseline Scenario (Kerang, Victorian Mallee)1980s - Burn/cultivate, grazed fallow, continuous wheat, sow after 25 May Cumulative improvements No-till/stubble retain, spray fallow, pea break crop, sow after 25 April Cumulative improvements Wheat Yield (t/ha) Baseline (1980s) 1.60 No-till /SR 1.84 No-till/SR + spray fallow 2.80 No-till/SR + spray fallow + pea break crop 3.45 No-till/SR + spray fallow + pea break crop + sow 25/4 4.01Kirkegaard and Hunt (2010) Journal Experimental Botany
  29. 29. Summary of key messages CA principles make sense - adoption is high Australian adoption is pragmatic (in system context) strategic tillage residue thresholds flexible sequences Evidence-based innovation needs to continue
  30. 30. CSIRO Plant IndustryJohn KirkegaardPhone: 02 62465080Email: john.kirkegaard@csiro.auThank youContact UsPhone: 1300 363 400 or +61 3 9545 2176Email: Enquiries@csiro.au Web: www.csiro.au
  31. 31. Strategic tillage for multiple constraints Water-repellent sandy topsoil Herbicide resistant weeds Stratified organic matter Compact, acid subsurface (Steve Davies DAFWA)Deep Yellow Sand
  32. 32. Strategic inversion tillage (1 year in 10) Plough ($70/ha) Herbicides ($70/ha) Year 1 Yield 2.5 t/ha Yield 1.6 t/ha Inversion to 25 cm depth Year 2 Reduced weeds Reduced water-repellence● Reduced soil strength● Improved pH profile (+lime)● Increased C in top 30cm(Steve Davies DAFWA) Yield 2.5 t/ha Yield 1.5 t/ha
  33. 33. 3. Improving productivity of modern, no-till farming Adoption is driven by Erosion control, water conservation ● Labour, machinery, fuel savings ● Timelines of operations ● Soil “health” benefits ● Improved productivity
  34. 34. Impact of season on response to no-till  HARDEN 1.0  WAGGA Yield diff (RDD-BC) (t/ha) Yield gain 0.5 0.0       -0.5  Yield loss   -1.0  -1.5 0 100 200 300 400 500 600 Growing season rainfall (mm) Insert presentation title
  35. 35. Biological constraints in Retain - DD Yellow leaf spot RhizoctoniaInhibitory Pseudomonas Insert presentation title
  36. 36. Wheat productivity improvements ?? Yield differences (t/ha) State No-till vs Cult Retain vs Burn NSW 0.01 - 0.31 Victoria 0.04 - 0.02 Western Aust. - 0.03 - 0.09 Queensland 0.06 - 0.14 South Australia - 0.02 - 0.02 Mean - 0.02 - 0.15Review of 39 long-term experiments (Kirkegaard 1995)
  37. 37. Adoption of No-till
  38. 38. CSIRO long-term study, Harden NSW (commenced 1990) • Increased earthworms • Higher microbial biomass • Disease suppression (Rhizoctonia) • Higher abundance of mites, nematodes, collembola • Diversity shifts in mites, nematodes, collembola • Maintain levels of organic C and N • Improved infiltration and less runoff • Good crop establishment in all years • Reduced crop vigour and yield (-11%) x • Rhizoctonia, inhibitory bacteria, yellow leaf spot x • Herbicide resistance x • Increased drainage x

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