1. The role of soil science in optimization of soil resource management
Per Schjønning
University of Aarhus
Faculty of Agricultural Sciences
NJF Congress
June , 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. 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
The sustainability issue

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

5. 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
Soils at stress

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

10. Indexing is a very effective way
Soil Function
Management Goals
Minimum Data Set
Indicator
score
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. Systemic science
The scientist (the subject) is part of the system (object) studied
Alrøe & Kristensen (2002)

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. properties and functions
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. Risk Assessment Extract from the EU Soil Framework Directive
(COM(2006) 232 final)
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. Organic C in soil,- what is the critical threshold?
g C 100 g-1 soil
Askov-trial
(110 years)
UNF
NPK
FYM
1.07
1.15
1.30
Case-study
(cash crop
<>forage crop)
Cash crop
Forage crop
1.45
1.97
Threshold ~1.1?
Threshold ~1.6?
Tilth class:
Acceptable
Poor
(Munkholm et al. 2002;
Schjønning et al. 2002)

24. Soil indicator thresholds

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

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

28. Proces control in agriculture
”DADD”
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!

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

30. Research chains
Large scale
Small scale
Mechanistic
Empirical
Quantitative
Qualitative
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
Empirical
Yield response,
drainage
Soil-tyre
interactions
(stress distribution)
Traffic
systems
Strain (deformation)
effects on soil functions
Stress
transmission
Soil strength;
stress-strain
relations
Mechanistic
Qualitative
Quantitative

32. in a modern network society
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. - exemplified for the soil compaction problem
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. More axles, better tyres
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. Market regulation (economics)
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. Reflexive objectivity
Risk assessment
Hazard identification
Hazard characterization
Exposure assessment
Risk characterization
Soil
function
Stability
- resistance
- resilience
Thresholds
- soil indicator
- management
The DPSIR concept
Research chains
But not indexed!