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Phosphate nutrition of crops in
lixisols from semi-arid West Africa
A very large proportion of the population living in the
semi-arid areas of sub-Saharan Africa lives from subsistence
agriculture and is suffering from extreme poverty and food
insecurity. Research conducted in West Africa has shown
that organic matter and phosphorus (P) inputs are essential
to restore the fertility of the fragile soils (lixisols) and to improve
crop production in the region. However, there is a lack of
information on how organic amendments affect P availability
to crops in these lixisols. This project conducted in the
centre of Burkina Faso aims at evaluating the effects of
organic amendments on soil P dynamics, on crop nitrogen
(N) and P nutrition, and on crop productivity. The model
crops used are sorghum (Sorghum bicolor), which is widely
cultivated in the area, and promiscuous cowpea (Vigna
unguiculata), which is an important cash crop.
From July to December 2009, we conducted a field study in
Burkina Faso. Different treatments were applied to cowpea
plants in the long-term field experiment in the Saria
research station: no nutrient input; low rate of nutrient inputs
as mineral and organic fertilisers; low rate of nutrient
inputs as mineral fertilisers; high rate of nutrient inputs as
mineral and organic fertilisers; and high rate of nutrient input
as mineral fertilisers.
First, we studied the impact of these treatments on cowpea
yields, soil available P, and soil microbial P. Weeds and
sorghum plants in the vicinity of cowpea plants were sampled
in order to assess the impact of these treatments on
nitrogen fixation by cowpea using the natural abundance
method.
At the beginning of the growing season, we identified with
farmers’ organisations 167 farms producing sorghum and/
or cowpea on lixisols in a 30 km radius around the Saria research
station. On each farm, a field was chosen in which
two microplots were installed to assess cowpea and/or
sorghum yields as well as selected soil properties. In addition,
the 167 households were surveyed in order to analyse
their socio-economic status and their agricultural practices.
The objective of this part of the project is to understand
the practices of farmers, and to compare these practices
with the fertilisation strategies used in the long-term trial.
Based on this, we aim at identifying fertilisation strategies,
which can be recommended to farmers.
Research fellow
Delwendé Innocent Kiba, INERA, Burkina Faso
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Supervisors
Emmanuel Frossard, ETH Zurich, Switzerland;
Michel P. Sedogo, Université polytechnique de Bobo,
Burkina Faso;
François Lompo, INERA, Burkina Faso
Collaborator
Saïdou Koala, CIAT, Kenya
Duration
May 2009 – May 2012
Capacity development
Research fellowships
A meeting with farmers’ organisations, Burkina Faso