The role of soil science in optimization of soil resource management

1. The role of soil science in optimization of soil resource management Per Schjønning University of Aarhus Faculty of Agricultural Sciences NJF Congress June 27-29 2007, Copenhagen U N I V E R S I T Y O F A A R H U S Faculty of Agricultural Sciences

2. Plan for presentation • Values in science and the Soil Quality concept • Risk Assessment (Soil Framework Directive) • Tools for analysing and regulating the system

3. The sustainability issue Change in agricultural research Focus areas • -> 1980 • Productivity • Efficiency • Breeding of new varieties • Pest control • Fertilization • 1980 -> • Effects on the environment • Biological diversity • Animal welfare • Soil degradation • Food quality

4. Science interaction with society Change in agricultural research Interested parties • -> 1980 • Farmers • 1980 -> • Farmers • Politicians (national and EU) • Consumers • NGO’s (the general public)

5. Soils at stress Change in agricultural research Soil management • -> 1980 • Organic manures • Light traffic • Low-energy tillage • Diversified crop rotations • 1980 -> • Mineral fertilizers • Heavy traffic • High energy input in tillage • Monocultures

6. The modern soil scientist at work Focus areas Actual management The sustainability issue Soils at stress Science interaction with society Interested parties

7. Soil quality The SSSA SQ definition Soil quality is the capacity of a specific kind of soil to function, within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation (Agronomy News, June 1995)

8. Minimum Data Set (MDS) Analogue with human medicine E.g. blood pressure, body temperature etc. (Larson & Pierce, 1991) Potential indicators in MDS Nutrient availability Total organic C Labile organic C Particle size Plant-available water capacity Soil structure Soil strength Maximum rooting depth pH Electrical conductivity

9. Scoring (indexing 0-1) of some selected soil quality indicators Andrews et al. (2002)

10. Management Goals Management Goals Management Goals Soil Function Soil Function Soil Function Soil Function Soil Function Soil Function Soil Function Soil Function Soil Function Minimum Data Set Minimum Data Set Minimum Data Set Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator Indicator score score score score score score score score score score score score score score score Index Value Index Value Index Value Caution! Indexing is a very effective way of hiding information! Karlen et al. (2004)

11. Values in science Fact: Several investigations have shown that compaction of soil below ~50 cm depth is persistent for decades or centuries Two different statements by soil scientists: ”No subsoil compaction is the criterion for sustainability regarding traffic in the field” Medvedev & Cybulko (1995); van den Akker & Schjønning (2004) ”Subsoil compaction should not create physical conditions that would reduce the saturated water conductivity beyond 10 cm d-1” Horn (2006); Lebert et al. (2007)

12. Soil quality is how well soil does what we want it to do

13. Alrøe & Kristensen (2002) Systemic science The scientist (the subject) is part of the system (object) studied

14. Reflexive objectivity The ability to perform science with full awareness of the values in play Based on Alrøe and Kristensen (2002)

15. Reflexive objective - some implications • Beware of the overall purpose of your research • Present the results together with your own priorities • Identify potential precautionary actions,- but present them separately

16. Plan for presentation • Values in science and the Soil Quality concept • Risk Assessment (Soil Framework Directive) • Tools for analysing and regulating the system

17. Stability of soil properties and functions Resistance = capacity to resist change Resilience = capacity to return to pre-stressed situation

18. EU Soil Framework Directive • Five threats to soil quality • Erosion • Organic matter decline • Compaction • Salinization • Landslides • Three major commitments (at the national level) • Identify risk areas • Set up risk reduction targets • Programme of measures for reaching those targets

19. Extract from the EU Soil Framework Directive (COM(2006) 232 final) Risk Assessment • Two EU projects preparing the risk assessment • ENVASSO • RAMSOIL

20. Risk Assessment The politician: Is this biological system at risk? The scientist: Let’s do a lot of measurements on the system to find out ! ? !

21. Risk Assessment Disturbing agent (management/ climate) Soil

22. Risk Assessment ”A process intended to calculate or estimate the risk to a given target organism, system or sub(population), including the identification of attendant uncertainties, following exposure to a particular agent, taking into account the inherent characteristics of the agent of concern as well as the characteristics of the specific target system” OECD (2003)

23. Threshold ~1.1? Threshold ~1.6? Organic C in soil,- what is the critical threshold? g C 100 g-1 soil Tilth class: Acceptable Poor (Munkholm et al. 2002; Schjønning et al. 2002)

24. Soil indicator thresholds

25. For soil organic matter, a management threshold may be e.g. some characteristic of the crop frequency Management thresholds

26. Plan for presentation • Values in science and the Soil Quality concept • Risk Assessment (Soil Framework Directive) • Tools for analysing and regulating the system

27. The scientist in a modern network society Government officer NGO-representative Farmer / consultant Researcher

28. Description of the system Management details (soil, crops etc) Decision on the most effective response (control) Analysis of the system Research results General knowledge Data from monitoring (indicators) Models Diagnosis / prognosis Is the system sustainable? NB: Explicit definition of sustainability! Proces control in agriculture ”DADD”

29. The scientist in a modern network society Government officer NGO-representative Farmer / consultant Researcher

30. Large scale Empirical Qualitative Quantitative Mechanistic Small scale Research chains Johan Bouma (1997) about traditional agricultural research: ”Too many answers were generated for questions that were not raised, while no adequate answers were provided for some acute problems” Bouma, 2001

31. The soil compaction problem Research topics and research chains Yield response, drainage Soil-tyre interactions (stress distribution) Strain (deformation) effects on soil functions Stress transmission Traffic systems Soil strength; stress-strain relations Empirical Mechanistic Qualitative Quantitative

32. The scientist in a modern network society Government officer NGO-representative Farmer / consultant Researcher

33. The DPSIR concept Responses Driving forces Impact Pressures State

34. The DPSIR concept - exemplified for the soil compaction problem More fertilizer Driving forces <Yield Pressures Status

35. The DPSIR concept - exemplified for the soil compaction problem Subsoiling Driving forces <Yield, >Erosion Pressures Dense soil

36. The DPSIR concept - exemplified for the soil compaction problem More axles, better tyres Driving forces <Yield, >Erosion Size of machinery, tyre types Dense soil

37. The DPSIR concept - exemplified for the soil compaction problem Market regulation (economics) Economy, profitability <Yield, >Erosion Size of machinery, tyre types Dense soil

38. The DPSIR concept - exemplified for the soil compaction problem Regulation (e.g. EU SFD) Driving forces <Yield, >Erosion Size of machinery, tyre types Dense soil

39. The DPSIR concept Reflexive objectivity • Risk assessment • Hazard identification • Hazard characterization • Exposure assessment • Risk characterization Soil function Research chains But not indexed! Stability Thresholds - resistance - soil indicator - resilience - management Reflexive objectivity