This study was presented during the conference “Production and Carbon Dynamics in Sustainable Agricultural and Forest Systems in Africa” held in September, 2010.

1. Swedish University of Agricultural Sciences
www.slu.se
Assessing multi-functionality of agroforestry systems in Western
Kenya. Food security, climate change adaptation and mitigation
Ingrid Öborn, Ylva Nyberg, Mattias Jonsson, Fergus L Sinclair
ABSTRACT: Agricultural productivity in sub-Saharan Africa is stagnant or declining and the rural population
is increasing which has resulted in land shortage and food insecurity. Increased pressure on natural
resources is also increasing the vulnerability to climate change. Although Africa accounts for only 3 to 4 % of
global carbon dioxide emissions, it will be among the regions of the world to be hardest hit by climate
change. To be able to enhance productivity and improve the livelihood in the long-term the declining trend in
soil fertility and tree cover has to be reversed and the resilience of farming systems enhanced. The overall
aim of the project is to contribute this.
This study focuses on carbon and nutrient fluxes and stocks, soil fertility and agricultural productivity in
small-holder farming systems in Western Kenya combining crops and trees (agroforestry) with and without
livestock. Field studies of fluxes and stocks of carbon and nutrients will be combined with simulation
modelling at field (plot), farm and landscape scale. The study will cover a chronosequence of agroforestry
farms in an area where trees have been promoted since 1995, a comparative study of farming systems with
different level of integration between crops, trees and livestock, and development of a set of quick and easy
field, farm and landscape level indicators of climate change adaptation potential.
The research will be carried out by the Swedish University of Agricultural Sciences (SLU) and the World
Agroforestry Centre (ICRAF) in collaboration with the NGO Vi Agroforestry (Vi-skogen). The newly initiated
project funded by Formas and Sida includes senior scientists as well as students at PhD and MSc level. At
present one PhD study and two Minor Field Studies are carried out within the project.

2. Swedish University of Agricultural Sciences
www.slu.se
Assessing multi-functionality of
agroforestry systems in W Kenya
Food security, climate change adaptation
and mitigation
Ingrid Öborna*, Ylva Nyberga,b, Mattias
Jonssona, Fergus L Sinclairc
a Swedish University of Agricultural Sciences (SLU)
*Email: ingrid.oborn@vpe.slu.se
b Vi Agroforestry, Kisumu, Kenya
c World Agroforestry Centre (ICRAF), Nairobi, Kenya

3. Swedish University of Agricultural Sciences
www.slu.se
Outline
• Multi-functionality
• What is agroforestry?
• Aim of the project
• Study areas and research plan

4. Swedish University of Agricultural Sciences
www.slu.se
Ecosystem services and multi-functionality
• Multi-functional agricultural system - produce
and provide multiple products and functions -
food, other products and services
• Ecosystem services - provisioning (food, fresh
water, wood, fibre, fuel..), supporting (nutrient
cycling, soil formation, primary production..),
regulating (climate, flood, disease, water
purification..), and cultural (aesthetic, spiritual,
educational, recreational..) (MA, 2005)

5. Swedish University of Agricultural Sciences
www.slu.se
What is agroforestry, and why?

6. Swedish University of Agricultural Sciences
www.slu.se
• Integration of trees with
crops and/or livestock
on farms and in
agricultural landscapes
Agroforestry – trees on farms and
in agricultural landscapes

7. Swedish University of Agricultural Sciences
www.slu.se
Trees and shrubs for fodder, fruit, fuel, shelter,
construction, medicine, green manure, mulch etc

8. Swedish University of Agricultural Sciences
www.slu.se
Tree, crop and livestock products for the
household and for generating income

9. Swedish University of Agricultural Sciences
www.slu.se
Overall aim
• Agroforestry is a promoted land use system in E
Africa to increase on-farm food production and
income, generate tree products and provide
environmental services (e.g. Amos Wafula Wekesa,
Carbon Project)
• The aim of the project is to assess and quantify
some of the multiple functions and to identify
potential synergies and goal conflicts at different
scales.

10. Swedish University of Agricultural Sciences
www.slu.se
• Focus on productivity, nutrient cycling, soil
fertility, carbon stocks and biological pest
control in small-holder agroforestry
systems, as compared to crop based
systems, in different landscapes
• Identify coping strategies for climate
adaptation, in particular to rainfall
variability, in two contrasting areas in W
Kenya
• Combine on-farm biophysical and
participatory studies with simulation
modelling at different scales.
The project will

11. Swedish University of Agricultural Sciences
www.slu.se

12. Swedish University of Agricultural Sciences
www.slu.se
Chronosequence
From maize to agroforestry
Tranz Nzoia (Kitale)

13. Swedish University of Agricultural Sciences
www.slu.se
Chronosequence
• Careful selection of on-farm fie
(6 ages 0-15 years and 5 of ea
age)
• Sespania and/or Calliandra
hedgerow systems with
maize/beans as main crops
• Representative soil samples fo
bulk density and total organic-
and N analyses.
• If successful – more studies w
carried out on these farms (nu
cycling, productivity, income,
biological pest control, etc.)

14. Swedish University of Agricultural Sciences
www.slu.se
Expected outcomes
Quantifications of the soil C and N stocks and soil bulk density in c
based and agroforestry systems of different ages
Simulations of the development of C and N stocks over time in orde
compare and contrast the field estimates with model predictions
(understanding effects of water, nutrient and light competition betw
trees and crops).

15. Swedish University of Agricultural Sciences
www.slu.se
Adaptation/Coping strategies for
rainfall variability
• Focus group discussions and questionnaires to
identify and score strategies.
• Semi-structured interviews with local advisers
• Compare:
– 2 climatic conditions (Trans Nzoia and Nyando)
– Farmers receiving or not receiving agroforestry advisory services
– Women and men perspectives

16. Swedish University of Agricultural Sciences
www.slu.se
Expected outcomes
• Understand of how climate, agroforestry
advisory services and gender affect the choice
of strategies and their importance
• A monitoring tool for assessment of households’
relative climate adaptation potential based on
local and scientific knowledge

17. Swedish University of Agricultural Sciences
www.slu.se
The project is funded by Formas-Sida and SLU

18. Swedish University of Agricultural Sciences
www.slu.se
Overall aim
To improve agricultural productivity and livelihood
for small-holder farmers in the long-term the
declining trend in soil fertility and tree cover has to
be reversed and the resilience of farming systems
enhanced. The overall aim is to contribute to this.
This study focuses on productivity, soil fertility, and
carbon and nutrient fluxes and stocks, in small-
holder agroforestry systems in W Kenya

19. Swedish University of Agricultural Sciences
www.slu.se
• Focus on productivity, nutrient cycling, soil fertility,
carbon stocks and pest control in small-holder
agroforestry systems
• Combine on-farm biophysical and participatory
studies with simulation modelling at different scales.
Specific objectives are to:
• Quantify soil carbon stocks in a chrono-sequence where trees
have been promoted since 1995
• Compare nutrient cycling and soil fertility in farming systems
with different level of integration between crops, trees and
livestock
• Study biological pest control in maize in agroforestry and
monoculture systems in different landscapes
• Identify coping strategies for climate adaptation, in particular to
rainfall variability, in two contrasting areas in W Kenya
The project will

20. Swedish University of Agricultural Sciences
www.slu.se
Studies planned/initiated
1. Pilot study: sugarcane vs agroforestry (MFS
Gustaf Magnusson Kroon & Ida Lindell, 1. 16.40)
2. Farmer adaptation/coping strategies for rainfall
variability – climate, advisory, gender (PhD)
3. Soil C and N stocks, and bulk density, in a 15
(20) year chronosequence - from crop (maize) to
agroforestry (mixed tree –crop) system (PhD)
4. Farm gate and field plot nutrient and carbon
balances
5. Field, farm, landscape modelling (WaNuLCAS,
NUANCES, Polyscape)

21. Swedish University of Agricultural Sciences
www.slu.se
Field, farm and landscape scale -
modelling
• The WaNuLCas model (van Noordwijk et al, 2004) will
be parameterised and used to simulate the development
over time of biomass and soil C and nutrient in the
agroforestry plots in the chrono-sequence. Explore
more/other options, O Andrén et al?
• In the farm level study the NUANCES framework will be
used to explore the effects on C and nutrient cycling of
increased diversity/complexity starting with a maize-bean
rotation (Wijk et al, 2009). Possible collaborations? S
Dahlin et al?
• For the landscape modelling, Polyscape will be used for
exploring synergies and trade-offs amongst the impacts
of trees on different ecosystem services depending on
where and to what extent trees are established (Pagella
et al., 2009). Explore links and joint interests with G
Nyberg et al?

22. Swedish University of Agricultural Sciences
www.slu.se