A presentation by Prof. Mike Swift

1. 5/27/2010
TOWARDS A FRAMEWORK FOR VALUING THE SOIL
BIOTA & ITS DIVERSITY:
APPROACHES & QUESTIONS.
What’s
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WHY DO WE NEED AN ECONOMIC VALUE? WHAT DO WE VALUE? THE BENEFITS HUMANS GAIN
FROM THE SOIL BIOTA
IE: THE ECOSYSTEM SERVICES PROVIDED BY THE SOIL BIOTA
1. To give the soil biota a reality that society,(and in
particular the decision makers) will accept. 1. Improved Nutrient Cycles .
2. Increased Sequestration of Carbon in Soils.
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Nothing speaks like dollars.
N thi k lik d ll
3. Reduced GHG emissions from Soils.
4. Improved Plant and Animal Health.
2. As a means of assessing the optimum agricultural 5. Improved Water Quality and Stabilised Water Cycles.
management practices by providing proper 6. Enhanced food production in agriculture.
costing.
See Handbook, Wall et al etc:
HOW DO WE VALUE THE SOIL BIOTA? – MAKING THE LINKS
AGRICULTURAL BENEFITS
Agricultural Intervention
1. IMPROVED NUTRIENT GAIN EG:
• Nitrogen from N‐fixation
• Phosphorus (and other nutrients) from mycorrhiza Soil Organism Abundance & Diversity
• Stabilised nutrient cycles [mineralisation/immobilisation ratio]
associated with enhanced decomposer community and increased
SOM. Soil Organism Processes
• Increased cation exchange capacity from increased SOM.
(Ecosystem Goods & Services)
(E t G d &S i )
2. IMPROVED HEALTH EG:
• Enhanced natural biological control
Agricultural & Environmental Benefits
3. IMPROVED WATER AVAILABILITY EG:
• Higher soil water holding capacity associated with increased SOM
and improved soil structure. Application of Economic Valuation Methods
• Uptake efficiency enhanced by mycorrhiza and improved soil pore
structure.
Value of Soil Biota
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2. 5/27/2010
WHAT ARE THE REQUIREMENTS FOR APPLYING
WHY DO WE NEED A FRAMEWORK? AN ECONOMIC VALUE TO THESE BENEFITS?
1. It is always useful to lay out the theory in detail to 1. The demonstration and measurement of the
ensure that our thinking is sound & our benefit.
assumptions justified.
3.. 2. The demonstration that the benefit derives from
2. The empirical evidence alone is unlikely to satisfy the soil biota ie:
the sceptics. ‐The demonstration that the benefit accrues only
when the target species/group of the soil biota is
present;
IE. We need to establish Rules of Proof for the
assertion that managing the soil biota may be a ‐The demonstration that the benefit is delivered by
viable economic option. one or more biological processes carried out by the
target biota.
THE LINK WITH MANAGEMENT THE LINK WITH MANAGEMENT (2) IMPACTS
TYPES & PATHWAYS OF INTERVENTIONS ANY intervention WILL affect, either positively or negatively:
(a) The Abundance
1. DIRECT actions to promote the diversity, abundance and ‐ of one or more species;
activities of the soil organisms (eg. inoculation), ‐ and thence the relative abundance, the balance
between species, FGs etc (some up some down);
( )
OR (more often): and/or
(b) The Activity
2. INDIRECT interventions by a variety of agricultural ‐ specific processes or a variety of processes (some
management practices targeted at enhancing crop beneficial, some detrimental); and balance of
processes.
productivity – that may be either beneficial or detrimental
to the soil biota abundance and diversity. and (perhaps)
(c) The Diversity (ultimately)
‐ of one or more variety, species , FG etc.
THE LINK WITH MANAGEMENT; IMPACT EXAMPLES: Valuing Agricultural Outcomes
PATHWAYS following Direct or Indirect Management or a
Mixture of Both.
Indirect Intervention Direct Intervention • Some of the experiments described later in this
session and in Session IV and the Posters establish
‘proofs’ of the delivery of the benefits of the soil
.
biota to crop productivity or similar agricultural
outcome eg:
Abundance +/‐
• Inoculation with LNB > Nitrogen gain valued via
fertiliser saving (Chianu et al)
Processes • Inoculation with Earthworms + Mucuna CC >
increased water infiltration valued via household
water value (Alarcon & Martinez, Posters 56‐58)
Benefits Diversity +/‐
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3. 5/27/2010
WHAT IS THE VALUE OF THE SOIL BIOTA IN TOTO:
VALUING SOIL QUALITY WITH INDICATORS SOME QUESTIONS & ISSUES
• We should clearly distinguish between the value of
Productivity the biota and the value of its Diversity? Are two
High SQI or SOM worms more valuable than one?
Low SQI or SOM
Low SQI or SOM
Time
•
SOME QUESTIONS & ISSUES SOME QUESTIONS & ISSUES
• How important is Diversity? • How important is Diversity?
• Recognise the limits of the FG concept: • Convergent and Multiple Benefits – limits of FGs.
A specific benefit may derive from several • Finally: Whose value is it anyway?
organisms or FGs and: ‐ Sectors of society;
Multiple Benefits may derive from the same
M lti l B fit d i f th ‐ Public v. Private.
organism or FG.
HOW DO WE VALUE THE SOIL BIOTA? – MAKING THE LINKS
Agricultural Intervention
Soil Organism Abundance & Diversity
Soil Organism Processes
(Ecosystem Goods & Services)
(E t G d &S i )
Agricultural & Environmental Benefits
Application of Economic Valuation Methods
Value of Soil Biota
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