INSAS launch meeting Dubai, UAE - 21 November 2019 Macoumba Loum

1. SPATIAL MODELLING OF THE SOIL SALINITY
VARIATION IN THE PEANUT BASIN OF SENEGAL
Dr Macoumba LOUM
National Institute of Pedology (INP)
Agricultural Ministry and Rural Equipment
SENEGAL
macoumbaloum@yahoo.fr

2. THE CONTEXT
• In the semiarid regions, irrigated land and wetlands are usually
affected by salinization due to the decrease of the annual
rainfall mainly because of climate change;
• In Senegal, salinization poses sustainable development issues
because the loss of production of millet, groundnuts, rice and
market gardening leads to risks of food insecurity and declining
incomes for the local farmers.

3. The Agro-ecological regions more affected by salinization process
Dominant crop production :
Peanut Basin : Millet and groundnut
Casamance : Rice and arboriculture
Rivey Valley : Rice
Eastern Senegal : Cotton
Niayes : market gardening

4. THE NEED TO MAP SALINITY PARAMETERS IS THE FIRST CHALLENGE
TO PROMOTE SUSTAINABLE MANAGEMENT OF SALT AFFECTED SOIL
 The estimation of the areas affected by salinity in Senegal gives various results :
 1,700,000 ha (LADA, 2003);
 925,000 ha (Fall, 2006);
 996,950 ha (INP, 2008);
 During the National workshop on the restoration and valorisation of salinity lands
(ANSTS in July 2019), the President of the Republic emphasized the need to carry
out the mapping of the salinity land at the national scale for knowing with accuracy
the areas affected by salinization .

5. THE RESULT OF DIGITAL MAPPING OF EC IN THE EXPERIMENTAL SITE OF INP
 In this study area (182.63ha), EC
values range between 40.00 and
542.00 mS/m;
 Random Forest (RF) and Ordinary
Kriging (OK) were compared using 72
soil sampling point;
 Calibration of the RF model includes
both SAR and optical spectral bands of
Sentinel;
 The results showed a decrease of the
RMSE with the RF model (19.46
mS/m) compared to the RMSE of OK
(26.6 mS/m).

6. THE MOST DISCRIMINANT VARIABLES IN THE RF MODEL
Findings showed also that
spectral band of Sentinel-2
(B8a, B9, B2, B11);
the water index ( NDWI);
the Radar band
(S1Simal_VH8 &
S1Simal_VH7) are the most
important variables in the
spatial modeling of EC with
RF.

7. THE PERSPECTIVES
 Capitalization of these results can contribute :
• To determine with accuracy the areas affected by salinization
at the national scale of the Senegal country;
• To elaborate strategies for the rehabilitation of the soil salinity
and to achieve food security;
• To share accurate information on soil salinity with the INSAS

8. Authors : LOUM M., CISSE EL H. S., DIAGNE P. N., FAYE G., DIEYE A. B., SOW M. A.
Thanks to Rosa Francaviglia (CREA) for the technical support
Thanks to FAO for Sponsoring our participation to the GFIME and in
the Lunch of INSAS