The ABACO project aims to reduce vulnerability of smallholder farmers in semi-arid Africa to climate variability by building capacity to design, evaluate, and implement conservation agriculture techniques tailored to local conditions. The project will involve farmers and researchers in innovation platforms to co-develop and assess social and economic viability of conservation agriculture alternatives across different scales and scenarios. Techniques will focus on rehabilitating degraded soils and increasing water productivity through a stepwise "aggradation" process to restore soil functions before fully implementing the three principles of conservation agriculture: zero tillage, permanent soil cover, and crop rotation.

1. ABACO
Agro-ecology based aggradation-conservation agriculture
Targeting innovations to combat soil degradation and food
insecurity in semi-arid Africa
Pablo Tittonell, Eric Scopel, Gerardo Halsema, Nadine Andrieu,
Helena Posthumus, Paul Mapfumo, Rabah Lahmar, Marc
Corbeels, Tom Apina, Jacqueline Rakotoarisoa, Florence
Mtambanengwe, Barry Pound, Regis Chikowo, Saidi Mkomwa

2. Problem statement
 Poor soil fertility and soil degradation limit food security
 CA may be low-cost investment strategy to increase water productivity and
resilience to climate variability, and reverse soil degradation
 But adoption by smallholders in sub-Saharan Africa seems to be hampered by:
 Concerns on initial yield decreases
 Lack of sufficient biomass for effective mulching
 Increased labour requirements if no access to herbicides
 Lack of access to and use of external inputs
 CA has to be tailored to local agro-ecological and socio-economic conditions
 Adoption of innovations is a non-linear process
 Sharing knowledge and building capacity through innovation platforms may
enhance adaptation and adoption of CA by smallholders

3. ABACO project
Objective: reduce vulnerability of smallholder
farmers to climatic variability by building capacity
through innovation platforms to design, evaluate
and implement targeted technological options for,
and mechanisms to promote adoption of,
conservation agriculture based on agro-ecological
principles to combat land degradation and food
insecurity in semi-arid sub-Saharan Africa.
Specific objectives:
1. To target CA to smallholders’ conditions
2. To involve farmers and researchers in co-
innovation platforms to facilitate
adaptation/appropriation
3. To assess the social and economic viability and
tradeoffs across scales and scenarios
4. To promote dissemination of CA alternatives
and approaches
5. To reinforce existing knowledge networks on CA

4. ABACO project
Project leader: Saidi Mkomwa – ACT
Consortium: ACT, CIRAD, CIRDES, EMBRAPA,
FOFIFA, SOFECSA, University of Greenwich
(NRI), Wageningen University, Yellow Window
Timeframe: 2011 – 2014
Funded by EU
Semi-arid areas of East (Kenya, Tanzania), West
(Burkina Faso, Mali) and Southern (Zimbabwe,
Mozambique, Madagascar) Africa
Building on previous projects: KASSA, CA2Africa

5. Project sites
A focus on dryland areas
(400 – 1200 mm)
CIRDES
ACT
SOFECSA FOFIFA

6. Stepwise ‘aggradation’
How fast does this happen?
What is the importance to
farmers’ livelihoods?
What indicators can
be used for
monitoring?
Aggradation: slow
process of soil
formation (borrowed
term from geography
used for alluvial
soils)
Rabah Lahmar (2009)

7. Stepwise ‘aggradation’
ABACO’s approach of aggradation/conservation agriculture consists of:
• Implementing measures traditionally promoted as soil and water conservation,
water harvesting technologies or (indigenous) agroforestry, during an initial
phase of soil restoration or ‘greening’.
• Only when a minimum efficiency of nutrient and water capture has been
achieved to allow increasing primary productivity, the three principles of CA may
become effective: zero tillage, permanent soil cover and crop rotation.
• Particularly in dry environments the response of soil productivity to soil
restorative measures may exhibit a faceted pattern characterised by an initial
response to increased water availability (i.e., the ‘greening’ effect) with a slight
loss in water productivity, followed by a response to increased soil fertility once
nutrients become available (resulting in greater water productivity).

8. Stepwise ‘aggradation’
Plant biomass Water productivity
(kg ha-1)
bi+2 ti+2
availability
Increased nutrient
bi+1 ti+1
bi ti
Increased water
availability
Transpiration
(mm)
wi wi+1

9. Soil rehabilitation
The response of a degraded agro-ecosystem to rehabilitation measures may be
fast or slow, and exhibit weak or strong hysteresis (i.e., h, h’ or h”). The periods t25%,
t50% and t100% represent the delay necessary to achieve 25 to 100% of the original
performance, efficiency or stock level.
The rate of responsiveness depends on:
• the indicator chosen to characterize the response (productivity, efficiencies, stocks),
• on the type of measure(s) implemented to restore productivity,
• on the biophysical properties of the agro-ecosystem, and
• on the behaviour of external factors (e.g. rainfall).

10. Feasibility and tradeoffs
gaseous losses harvest
Crop fertilizer
erosion
crop Tree
uptake
N2 gaseous losses harvest
leaching fixation
Prunings
Crop
mulch fertilizer
Experimental field erosion
competitive tree uptake crop
uptake
‘safety-net’ tree uptake
On-farm leaching
Landscape
NPK
NPK
NPK

11. Innovation platforms
Rural
Other community Other
stakeholders stakeholders
Action Field
research schools
Co-
innovation
platform
Research for Promotion &
development extension
Knowledge
networks
Other
stakeholders
Based on Learning
Centres model, Zimbabwe

12. The 5 ABACO principles
1. Rehabilitation of degraded soils to restore biomass productivity, in order
to secure the various functions of CA that depend on above and
belowground plant biomass;
2. Increased water productivity and soil water buffering capacity to face
increasing risks associated with climate change, creating more
conducive conditions for farmers’ investments;
3. Intensifying agro-ecological functions to capitalise on natural
interactions, increase resource use efficiency and reduce dependence
on external inputs;
4. Embed these principles in sustainable innovation support systems that
recognise the complexity and non-linearity of agricultural innovation
processes;
5. Institutionalization of enabling policies and market conditions so as to
facilitate uptake and promotion of CA among smallholder farmers.

13. ABACO activities
1. On-station and on-farm field experimentation
2. Gender-sensitive characterisation of conditions for implementing CA
technologies and gender mainstreaming of all activities
3. Action research with rural communities
4. Participatory & model-based scenario analysis and tradeoffs evaluation
5. Training & capacity development
6. Dissemination
7. Policy analysis and recommendations

14. The ABACO project
FP6 CA2Africa FP7 KASSA
Existing CA knowledge
Best-bets
Site charac- Supportive
terisation & basic
diagnosis Field testing research
& niche
Project progress
targeting Field
demonstra-
Analysis tool tion, farmer
development valuation &
Feasibility adaptation
Policy and tradeoffs
analysis evaluation Policy
recommen-
Material dations
development
Dissemina-
tion & out-
reach
Field activities
Innovation platforms

15. Organisational matrix
Work packages
WP1. Diagnosis, design WP2. Innovation WP3. Feasibility and WP4. Dissemination,
Themes and testing support trade-offs evaluation impact and networking
Water productivity and Design and testing of Farmer testing & Evaluation of CA Documentation of 4W(*),
climatic variability water capture and climate adaptation of water alternatives under climatic adoption and adaptation
coping alternatives based capture and climate scenarios, risk and strategies; Mechanisms of
I on CA coping alternatives vulnerability dissemination-learning
Soil rehabilitation and Design and testing of CA Farmer testing & Evaluation of C and nutrient Documentation of 4W(*),
integrated fertility alternatives for soil adaptation of soil flows and tradeoffs for CA adoption and adaptation
management rehabilitation and fertility rehabilitation & fertility implementation from field to strategies; Mechanisms of
II management management alternatives regional scale dissemination-learning
Agroecological functions Diagnosis & identification Farmer testing & Multi-criteria evaluation of Assessment of externalities
and environmental of biodiversity-mediated adaptation of biodiversity CA functions & and service provision (e.g.
services CA functions, definition of mediated functions, sustainability: tradeoffs from carbon sequestration,
III indicators valuation of indicators field to regional scale biodiversity, water saving)
Livelihood, gender and Gender-sensitive socio- Innovation systems Evaluation of social & Analysis of adoption,
policy evaluation economic diagnosis of support, organisational economic viability of CA; adaptation and learning
enabling environments & landscapes, capacity tradeoffs under policy and processes; Policy design &
IV local perceptions needs & development market scenarios recommendations
Methods and tools Surveying & diagnosis, on- Stakeholder analysis, farmer Dynamic and bio-economic Meta-analysis, stakeholder
farm & on-station groups, action research & modeling at different scales, platforms, dissemination
experiments, measurements training participatory evaluation events & material
(*) the 4W stand for “What Worked, Where and Why?”

16. WP0: Coordination
Flows WP1: Diagnosis,
design and testing WP2: Innovation
support
WP1-W WP1-E WP1-S WP1-M
Supportive Innovation
research platforms
Field testing Diagnosis &
& targeting characterisation
WP3: Feasibility and
trade-offs evaluation
Participatory
Model evaluation
development
Scenario
analysis
WP4: Dissemination
and impact assessment
Network
reinforcement
Policy analysis
Training of &design
trainers Dissemination
& outreach

17. Concluding remarks
• ABACO is a concept relying on 5 principles,
borrowing from ISFM, agroecology and
innovation systems
• We cannot ‘conserve’ what has already been
degraded – a stepwise ‘aggradation’ phase is
needed
• The EU-funded ABACO project targets
innovations to combat food insecurity in
semiarid areas
• Four transversal themes organise the research
questions
• Four work packages delineate the project
activities
• We are not starting from zero…

18. For questions:
On water productivity: gerardo.vanhalsema@wur.nl
On soil fertility: p.mapfumo@cgiar.org
On diagnosis & design: pablo.tittonell@cirad.fr
On feasibility & tradeoffs: m.corbeels@cgiar.org
On agro-ecological functions: eric.scopel@cirad.fr
On innovation platforms, adoption & gender: h.posthumus@gre.ac.uk
On ABACO: saidi.mkomwa@act-africa.org
A B A C O
THANK YOU!