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Ghent University Vrije Universiteit Brussel (2014)

Addressing climate variability in agricultural land evaluation. Case study for crop production in Far North Cameroon

Hemerance Menekeu Awamu

Titre : Addressing climate variability in agricultural land evaluation. Case study for crop production in Far North Cameroon

Auteur : Hemerance Menekeu Awamu

Université de soutenance : Ghent University Vrije Universiteit Brussel

Grade : Master of Science in Physical Land Resources 2014

Résumé
Given that Cameroon, like most developing countries, is strongly dependent on agriculture, the effect of climate variability on the agricultural sector is capable of hastening the problem of food insecurity and the threat of starvation. This is especially true in the case of the Extreme-Northern region of Cameroon, characterized by its semi-arid climate, hence making it the most fragile zone in the country. In this area, natural variability of rainfall is likely to contribute to variability in agricultural productivity. This impact of climate variability on crop production is rarely accounted for in traditional land evaluation methods. This thesis aims to address the sensitivity of the traditional land suitability classification to climate variability. Using time series of climatic data on rainfall (1951 2004), temperature (1960-2004), reference evapotranspiration (1960-2004) and relative humidity (1968-1982), climate variability was studied and related to variations in yield of sorghum (1984 2004), an important subsistence crop, and cotton (1984-2004), the main cash crop in the region. Finally, the sensitivity of the FAO crop-specific land suitability classification to climate variability and selection of sowing date was assessed. Evaluation of rainfall by means of several indices revealed that the Extreme-Northern Cameroon is a region with a sharp seasonal contrast, with rainfall fluctuation at inter-annual, intra-annual and decadal scales. The length of growing period of 135 days on average, varied a lot from year to year, going from a minimum of 93 days to a maximum of 192 days. Even as 91% of the annual rainfall fell within the growing period, correlation between crop yield response to annual rainfall was mainly limited to 1990-1999, a period during which agricultural activities were highly dependent to climate. While suitability classification using long-term averages demonstrated that in all the years, climate will be marginally suitable for cotton production, it was found in the classification using variation in climatic characteristics with fixed sowing date approach that 4 out of 43 years were wrongly classified, and 8 out of 43 years were misclassified with the variable sowing date approach. Moreover, the classification using the probability of exceedance showed that in two out of ten years, climate will be unsuitable, but potentially suitable for cotton production. These important information missing in the suitability assessment when using only long term averages are reliable to understanding the impact of climate variability on yield. These findings suggest that the accuracy, reliability and risk-averseness of land evaluation assessments can be increased by explicitly taking into account climate variability into the methodological approaches. Future research can be conducted to develop improved methods on how to better incorporate the climate variability into the land suitability assessment.

Mots clés : climate variability, cotton, sorghum, land evaluation, Extreme-Northern Cameroon, growing period, dry spell

Version intégrale

Page publiée le 15 novembre 2015, mise à jour le 23 janvier 2018