Cropping system sensitivity to climate change in the northern uplands of Lao PDR. An agroclimatic modeling approach

Lechevallier Esther. 2015. Cropping system sensitivity to climate change in the northern uplands of Lao PDR. An agroclimatic modeling approach. Montpellier : Montpellier SupAgro, 67 p. Mémoire d'ingénieur : Agronomie. Production végétale durable : Montpellier SupAgro

Titre français : Sensibilité des systèmes de culture des régions montagneuses du nord du Laos au climat actuel et futur

Encadrement : Marrou, Hélène ; Affholder, François ; Lienhard, Pascal

Résumé : In addition to the actual context of agrarian transition, subsistence agriculture in northern upland of Lao PDR will face climate change. The aim of this project was to describe the cropping systems in northern upland of Lao PDR and to assess their sensitivity to climate. To begin with, farmers were interviewed to identify the cultivated cultivars and their crop cycle dynamics. Field measurements and yields data analysis helped with intensification level determination. From the collected information on cultivars and cropping systems, a simple agroclimatic model, potential Yield Estimator (PYE), has been calibrated in order to simulate growth of 4 cultivars (1 glutinous rice cultivar, 2 maize cultivars and 1 job's tear cultivar) in potential and water-limited conditions. Then a virtual experiment has been set up to simulate the growth of these cultivars in cropping systems designed based on collected information. Several modes were tested for variable input parameters (runoff level, soil AWC and soil depth, sowing date). This virtual experiment, run for 16 years of historical weather data (1985-2000) and for 16 years of virtual weather data representing a possible evolution of climate in the future, led to an assessment of cropping system sensitivity considering several features. Cultivars potential yield has been analyzed regarding sowing date. Then the analysis of water-limited yield and its sensitivity to runoff and soil properties revealed an optimum sowing window for which water limited yield is close to potential yield and its interannual variability is low. Generally, water-limited yield is low sensitive to runoff but its sensitivity (average decrease in yield and interannual variability) to AWC and soil depth is increasing when sowing dates digresses from optimum sowing window. Climate change would decrease the potential yield but should not affect critically the relative water-limited yield and its variability due to soil and runoff properties. Drainage, another output of the model, is supposed to increase with climate change, which lead to a questioning regarding use of fertilizer to cope with fertility losses due to fallow-period shortening

Résumé (autre langue) : In addition to the actual context of agrarian transition, subsistence agriculture in northern upland of Lao PDR will face climate change. The aim of this project was to describe the cropping systems in northern upland of Lao PDR and to assess their sensitivity to climate. To begin with, farmers were interviewed to identify the cultivated cultivars and their crop cycle dynamics. Field measurements and yields data analysis helped with intensification level determination. From the collected information on cultivars and cropping systems, a simple agroclimatic model, potential Yield Estimator (PYE), has been calibrated in order to simulate growth of 4 cultivars (1 glutinous rice cultivar, 2 maize cultivars and 1 job's tear cultivar) in potential and water-limited conditions. Then a virtual experiment has been set up to simulate the growth of these cultivars in cropping systems designed based on collected information. Several modes were tested for variable input parameters (runoff level, soil AWC and soil depth, sowing date). This virtual experiment, run for 16 years of historical weather data (1985-2000) and for 16 years of virtual weather data representing a possible evolution of climate in the future, led to an assessment of cropping system sensitivity considering several features. Cultivars potential yield has been analyzed regarding sowing date. Then the analysis of water-limited yield and its sensitivity to runoff and soil properties revealed an optimum sowing window for which water limited yield is close to potential yield and its interannual variability is low. Generally, water-limited yield is low sensitive to runoff but its sensitivity (average decrease in yield and interannual variability) to AWC and soil depth is increasing when sowing dates digresses from optimum sowing window. Climate change would decrease the potential yield but should not affect critically the relative water-limited yield and its variability due to soil and runoff properties. Drainage, another output of the model, is supposed to increase with climate change, which lead to a questioning regarding use of fertilizer to cope with fertility losses due to fallow-period shortening.

Mots-clés libres : Climate change, Crop model, Laos, Potential yield, Water stress

Auteurs et affiliations

• Lechevallier Esther, Montpellier SupAgro (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/590893/)

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