NORTH-SOUTH CENTRE - ETH - North-South Centre North-South ...

Reversing soil degradation by tropical
legume trees using GIS analysis
In our project, we are evaluating and analysing the effects
of the incorporation of Gliricidia sepium on soil productivity
and the livelihoods in the Meegahakivula region, Sri Lanka.
Our integrative approach includes agronomic, socio-economic
and geographical aspects.
The extensive on-farm field trials of the agronomic component
showed that an increase in the site inclination as
well as increased continuous cropping decrease soil fertility,
especially organic matter and soil nitrogen contents.
In addition, productivity in crop fields and home gardens is
most restricted by increasing inclination and drought. Frequent
incorporation of green or composted manure from
Gliricidia trees may enhance soil organic matter content
and crop yields – more pronounced at smaller slopes and in
home gardens. Home gardens are usually characterised by
greater soil fertility than crop fields. Increasing their use
may contribute to improved food security and a higher
income through direct marketing of vegetables.
The economic component analysed different driving forces
in the economic environment of these smallholder hill
country farming systems. Changes in prices of products and
production factors, salary-levels, or off-farm employment
opportunities influence labour allocation decisions and the
labour-capital relationship. Data showed that flows of cash
and goods are fluctuating around a steady state. A sustainable
increase of income through market integration of these
farming systems needs external investments and policies
to create beneficial conditions. A simulation model is used
to analyse the sensitivity of these systems to changes in the
economic environment based on their portfolio. The portfolio
can be either more self-sufficiency- or market-oriented.
The photogrammetric project component generated the
Meegahakivula Geographic Information System in form of
a common database incorporating the agronomic, socioeconomic,
geographic and topographic data about the
farming systems. It allows for analysing spatially-related
datasets. The Meegahakivula GIS is a web-based platform,
which provides a database of variables from various thematic
backgrounds. It also has the potential to inform extensionists,
as such contributing to the knowledge transfer into
agricultural practice.
Our project demonstrates the potential of introducing
a tree species to improve productivity and sustainability
of crop production in smallholder hill country farming
systems, taking the diversity of livelihood strategies into
account.
Project leaders
Peter Stamp
Armin Grün
Bernard Lehmann
39
Contact persons
Chaminda Egodawatte
Henri Eisenbeiss
Martijn Sonnevelt
Collaborators
Ravi Sangakkara and Cyril Bogawahatte,
Peradeniya University, Sri Lanka;
K.R.M.U. Bandara and Lal Samarakoon,
AIT, Thailand
Duration
October 2006 – October 2010
Thematic clusters
Fodder resources and feeding strategies,
Livestock and environment,
Livestock-based value chains and
policy analysis
Research collaboration
Livestock systems research
Farmers transporting Gliricidia and other wood species to a market
to sell as firewood, Badulla, Sri Lanka