The document discusses the economic assessment of soil erosion and its management, emphasizing the importance of valuing soil ecosystem services and understanding the costs and benefits associated with soil conservation practices. It highlights the need for policies that recognize both individual farmer and societal gains while addressing externalities that are often overlooked in market prices. The case study in Kenya indicates variability in return on investment for different soil conservation practices and calls for targeted policy to support cost-effective soil management solutions.

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2. Addressing soil erosion
through policy and
economic assessments
Professor Lindsay C. Stringer-
University of Leeds, UK
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3. The value of soil
• We are often unaware of the value of soil
and its ecosystem services until it is too
late and soil has been eroded
• Valuation can identify costs and benefits
of different options and identify where
policy support is needed to help
stakeholders to manage soils more
sustainably
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4. Economics of soil erosion
• Most soil management results in
erosion rates > background rates where no cultivation
• Soil conservation implies redistributing resource use rates
into the future
• Soil erosion implies redistributing resource use rates
towards the present
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5. Farmer perspectives
• Direct costs, e.g. labour, materials,
equipment, structures for both
initiation and maintenance
• Opportunity costs e.g. foregone
output that land taken for erosion
control could have been used for
• Benefits come from soil as an asset
that provides income, so can be
assessed using e.g. yields,
representing gains in production
and income into the future
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6. • Cost benefit analysis (CBA) compares costs and benefits of the
consequences of soil erosion and any steps taken to reduce it
• Cost and benefits accrue to all members of society, not just
farmers
• Farmers are concerned with on-site costs and benefits; society
with off-site, external costs
• Externalities occur during production or consumption, e.g. soil
erosion on farmland leads to downstream sedimentation,
while upstream soil conservation creates a positive externality
• Externalities are not reflected in market prices or farmer
decision making, yet have an economic value
Scale matters…
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7. Assessing the costs and benefits of
soil conservation in Kenya
• For a given soil conservation practice, implemented over a
defined area of land for a specified period of time:
• Calculate costs
• Calculate benefits
• Discount future costs & benefits
• Calculate a net present value and return on investment
period
• Does it makes financial sense for farmers to invest
in soil conservation?
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8. Lake Victoria
Lake Kanyaboli
Lake Sare
Lake Namboyo
Lake Victoria
SIAYA
BUNGOMA
KAKAMEGA
Western Kenya case study
Dallimer et al 2018
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• Focus on most common crops
in the most widespread agro-
ecological zone
• Stratified random sample of 60
smallholder (1-2ha)
subsistence farmers
• Time horizon 2015-2030,
paralleling Kenya’s Vision 2030
• Discount costs and benefits to
present values using three
discount rates: 3.5%, 5%, 10%

9. Manuring
 Return on
investment:
payback period
always short,
regardless of
discount rate or
county
 NPV varies
between
counties
Bungoma
Kakamega
Siaya

10. Intercropping
 Return on
investment: payback
period immediate
regardless of discount
rate
 Same pattern across
all counties

11. Terraces
 Bungoma
 Kakamega
 Siaya
 Return on
investment:
payback period
highly variable
 Farmers in Siaya
do not see their
investment
repaid

12. Agroforestry
 Bungoma
 Kakamega
 Siaya
 Only for certain
discount rates in
Kakamega is
investment
repaid
 Farmers in
Bungoma and
Siaya will not see
a return on their
investment in the
time periods
assessed

13. Policy suggestions
 Policy should target promoting the right soil
conservation practices to the right areas
 Promote simple, low cost, practices for
maximum impact on individual farmers
 Policy needs to recognise wider societal gains
and ensure farmers do not carry all the costs
 Subsidy schemes
 Payments for ecosystem services

14. Landform Soil depthLand use Distance to
stream
Slope
Applicable
Not applicable
SPA01 Reduced
contour tillage
SPA04 Boqueras
water harvesting
Aggregate
applicability
DESMICE – Applicability limitations of
soil conservation strategies (Fleskens et al 2016; 2014)

15. The standard cost reported for TUN11 is 50 US$
ha-1 for fencing. An allowance was made for
transport costs of fencing material (up to
US$3.36) and slope (up to US$3.00). The
resulting map of investment costs ranges from
US$ 50.11 (blue) – US$ 54.91 (red)
TUN11 Rangeland resting
Spatial variability in investment costs

16. [A – B – C + D] =
Annual cash flow series for
each technology and grid cell
Production
foregone
without case
X Value (€)
X Value (€)
Foregone
costs of:
- Production
Costs of:
- Production
- Maintenance
- Other (e.g.
area loss)
DC
BAProduction
with applied
technology
Cash flow series are constructed for
each grid cell

17. • Terraces are simulated in a sub-grid
model
• Sub-grid model returns simple output
to grid cells
SPA02 Vegetated earthen terraces
Simulation of biophysical effects of e.g.
terraces

18. Spatially-
Explicit Net
Present
Value (NPV)
Technology
options Potential adoption
(based on profit
maximisation)
Valuation of cash flows over same time
horizon and discount factor
Financial cost benefit analysis

19. Do we just need more research?
• Having economic information on costs of soil erosion,
inaction and value of benefits helps, but isn’t a
solution on its own
• Challenges link to a combination of overlapping
barriers, specifics of which differ according to each
country:
Political and institutional
Capacity and resourcing
Social and cultural
Legal and regulatory
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20. Whose responsibility?
Barriers: Political and institutional; Capacity and resourcing;
Legal and regulatory
• Soils cross-cut the remit of multiple ministries and
departments
• Difficult to avoid conflicts and contradictions
• Requires leadership but also strong interplay and
coordination
• Other stakeholders (e.g. media, private sector) can be useful
allies but may also have counter-interests and act as
barriers, especially if mainstreaming soil erosion into policy
challenges established political-economic interests

21. Knowledge, tools, data and
information deficits
Barriers: Capacity and resourcing; Social and cultural
• Mismatches between supply and demand
• Lack of collaboration and knowledge /information sharing
• Scale of knowledge and data not always appropriate
• Local and indigenous knowledge often undervalued
• Substantial training opportunities provided but staff move
leaving institutional voids. Knowledge and information not
always passed on

22. What do policymakers need to know?
• Need to match supply and demand for knowledge, tools,
data and information
• Information needs to be available, visible, accessible and
compatible with policy processes (Stringer and Dougill,
2013)
• Compatibility links to policy cycles as well as the format of
information – build from the strengths, don’t start with
criticism

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Stringer and Dougill (2013)

24. Lessons for policy
• Options exist that reduce soil erosion and tools are
available to assess their economic feasibility
• Low cost measures that deliver ‘quick wins’ are
preferred by farmers and can help reach policy goals
• Design and opportunity costs need full consideration
before rolling out policy measures
• CBA can be applied spatially to examine the
profitability of different measures and what this might
mean for farmer adoption
• Research alone is not enough: supply and demand for
information need to be balanced and barriers to
addressing soil erosion in policy need to be overcome
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25. Acknowledgements
Thank you to Martin Dallimer and Luuk Fleskens for their inputs to this
presentation; GIZ who funded the Kenya case study and the Economics of
Land Degradation Initiative; and to the EU who funded the work on
PESERA-DESMICE
References
Dallimer M, Stringer LC, Orchard SE, Osano P, Njoroge G, Wen C, Gicheru P. 2018.Who uses sustainable
land management practices and what are the costs and benefits? Insights from Kenya. Land
Degradation and Development 29(9), 2822-2835
Fleskens L, Nainggolan D, Stringer LC. 2014. An exploration of scenarios to support sustainable land
management using integrated environmental socio-economic models. Environmental
Management 54, 1005-1021
Fleskens L, Kirkby MJ, Irvine BJ. 2016. The PESERA-DESMICE modelling framework for spatial
assessment of the physical impact and economic viability of land degradation mitigation technologies.
Frontiers in Environmental Science 4:31
Stringer LC, Dougill AJ. 2013. Channelling science into policy: enabling best practices from research on
land degradation and sustainable land management in dryland Africa. J Environ Management 114,
328-335
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