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N° 442
October 2013
Climate change: a promising future
for cotton in Cameroon?
(© JRC / A. Leblois) In Cameroon.
While climate change threatens most crops in Africa, its impact could be less on cotton cultivation in Cameroon. A new study by researchers from IRD and its partners shows that the
expected climate change over the coming decades should not have a negative effect on Came!""#$%#& '(%#)%)$"#*+&,-%$#*)& %((& "..*/& )01$!& '!".23)$4$)5& *0"2(.& 141#& $6'!"41& *$-#$73%#)(5& 85&
2050, thanks in particular to conservation agriculture practices adopted by the country. These
projections, made according to six climate scenarios based on different farming techniques, are
optimistic for Cameroonian producers, for whom cotton is the leading cash crop and often the
only alternative.
Useful information
West and Central Africa is the third largest exporter of cotton, after the United States and Central Asia. In Cameroon, cotton is the
main cash crop, with 30% of cultivated land in the north of the country and an annual production of close to 200,000 tonnes in 2012.
It has been cultivated there since the 1950s.
Glossary
Evapotranspiration: combined effect of the evaporation of water on the surface of the soil and plant transpiration.
Direct sowing under plant cover: this technique consists of sowing directly – without ploughing – under permanent plant cover (residues from the previous crop), which reduces water loss and restores fertiliser to the soil.
9$((%-1:&6130%#$3%(&"'1!%)$"#/&;0$30&3"#*$*)*&"<&81%)$#-&"!&3!2*0$#-&)01&78!1&"<&'(%#)&*)16*&)"&*1'%!%)1&)01&;"".5&'%!)*&"<&)01&78!1&
and obtain hemp.
Photosynthesis: fundamental biological process that converts solar energy into sugars from carbon dioxide and water and thus provides energy to plants.
CONTACTS
From observations made in stations and plots
from 2001 to 2005 and in 2010 in North Cameroon, the research team simulated the impact
of climate forecasts for the next 40 years on the
growth of cotton plants. To do this, they calibrated then applied the crop model called «Cropgro»
using several farming techniques and six climate
scenarios in the north of the country according to
projections that, among other things, served as
the basis for the fourth IPCC report. While climate
projections differ for some variables such as rainfall, the average of these scenarios shows stable
rainfall, higher temperatures and evapotranspiration. According to the researchers’ simulations,
the predicted 0.05°C rise on average per year is
expected to slightly increase the annual yield of
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than 2.5 kg per hectare according to the climate
scenarios considered.
Conservation agriculture is essential
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combination of several factors. Firstly, how the
cotton is grown is crucial. Field productivity is
highly dependent on local farming practices. For
ten years, Cameroon has adopted measures to
restore land with conservation farming techniques,
such as sowing under plant cover, tillage or mulching. Many farming practices that would limit the
deterioration of cultivated soils are at work in the
north of the country and, according to the researchers’ simulations, counteract the effects of climate change on crops.
CO2 has a fertilising effect on cotton
Climate factors themselves could have an unex'13)1.& '"*$)$41& $#B21#31/& %#.& %6"#-& )016/& )01&
increase in the percentage of carbon dioxide.
Cotton belongs to a type of plant for which CO2
in the atmosphere stimulates photosynthesis (like
soya, peanuts and a majority of plants, including
all trees). The new study shows that this fertilising effect will help offset other impacts of climate
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Cameroon could increase by around 30 kg per
hectare. Nevertheless, the effect of CO2 in the
atmosphere on crop yields remains controversial:
it varies greatly depending on the model of plant
growth used.
inputs needed for cotton cultivation. In addition,
more than the total rainfall, the start date and duration of the rainy season are paramount. A previous
study has shown that these two parameters can
be used to predict annual cotton yields. Despite
the optimistic forecasts of this new work, a steady
impoverishment of soil remains, as well as risks
related to inter- and intra-seasonal variability and
to changes in the price of cotton on the international market, driven by global giants in the sector,
the United States and Asia. An insurance system
with a compensation level based on these rain
indices could consolidate the positive outlook for
the Cameroon cotton sector, by limiting the debt of
the poorest producers.
Coordination
Gaëlle Courcoux
Information and Culture Department
Tel: +33 (0)4 91 99 94 90
Fax: +33 (0)4 91 99 92 28
7301*%3)2=$!.+<!
www.ird.fr/la-mediatheque
Partners
CIRAD, CIRED, Maroua Regional Agricultural
Research Centre in Cameroon.
References
GERARDEAUX E., SULTAN BENJAMIN, PALAI O., GUIZIOU C., OETTLI P., NAUDIN K. Positive effect of climate change on cotton
in 2050 by CO2 enrichment and conservation agriculture
in Cameroon. Agronomy for Sustainable Development,
2013, 33 (3), p. 485-495. ISSN 1774-0746
LEBLOIS A., QUIRION P., SULTAN BENJAMIN. Price vs. weather
shock hedging for cash crops : ex ante evaluation for cotton producers in Cameroon. Palaiseau : Ecole Polytechnique, 2013, 34 p. multigr. (Cahiers de Recherche - Ecole
Polytechnique ; 03).
Media Contact
Cristelle DUOS
Tel: +33 (0)4 91 99 94 87
'!1**1=$!.+<!
Contacts
Benjamin Sultan, researcher at IRD
Tel.: +33 (0)1 44 27 84 67
81#C%6$#+*2()%#=$!.+<!&
LOCEAN (Laboratory of Oceanography and Climatology) (IRD / CNRS / National Museum of
Natural History / Paris University 6)
The importance of a season of regular rain
Antoine Leblois, researcher at the Joint Research Centre of the European Commission
Tel.: +39.0332.78.5023
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The effect of rainfall change on cotton yield also
differs from that of crops such as maize, sorghum
and millet. In particular, excess water threatens
cotton, with increased runoff, leaching of soil and
Edward Gérardeaux, researcher at CIRAD
Tel: +33 (0)4 67 61 56 87
-1!%!.1%2A=3$!%.+<!&
Subscribe to the scientific news of the IRD: fichesactu@ird.fr
Indigo, IRD Photo Library
Daina Rechner
Tel: +33 (0)4 91 99 94 81
$#.$-"=$!.+<!
Photos : www.indigo.ird.fr
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© IRD/DIC, Octobre 2013 - Conception et réalisation graphique : L. CORSINI
Improved yield