Profils agronomiques de 15 cultures dominantes au Sahel

This document aimed to provide a framework for evaluating the impact of climate change on the main crops in the Sahel region. The process outlined in the document involves developing a phenological profile for each crop, including normal levels of response to climatic parameters, defining "rainfall years" for each considered crop, and searching for climate data related to the occurrence, duration, and magnitude of events exceeding the thresholds defined by the profiles. The document focuses on the first component, detailing the profiles of 15 dominant crops in the Sahel region. These profiles include parameters of growth that can be used to evaluate trends in intra-seasonal climatic characteristics observed to determine when a critical tolerance threshold for a crop has been exceeded. The profiles are based on existing research documents, complemented by interviews with experts. Each profile describes the geographical distribution and importance of the crops, their development cycle, and their needs in precipitation and temperature at different stages of their development. The profiles also identify growth thresholds related to soil conditions, water availability, and temperature, and provide a description of the crop's ability to adapt to climate change. The results of developing these 15 profiles reveal several general findings. All crops have basic temperature requirements to reach a given phenological stage. If the temperature exceeds the established thresholds at any stage, plant growth and development, as well as yield, may be affected. However, a crop can survive even if the temperature exceeds these thresholds if other conditions are optimal. For example, excessive heat can be compensated by high soil humidity. The crops' requirements for precipitation are extremely difficult to correlate with precipitation because other factors affect the available moisture for a plant. For instance, plants growing on steep slopes or on soils with lower water-holding capacity require more precipitation. Evapotranspiration levels, dictated by temperature, solar radiation, and plant structure, also affect the available moisture for a plant. The surrounding vegetation can also limit water availability. The interaction between crops and soil types, as well as other growth parameters, is complex. However, in general, clay soils and soils with higher organic matter content have more potential to retain water than sandy soils. This characteristic can mitigate the effects of reduced precipitation, drought sequences, and rising temperatures caused by climate change. The profiles established are only for the main types of crops and for the entire range of varieties cultivated in the Sahel region; they do not cover specific varieties. A phenological profile for a variety would require complete data on the variety's performance, genetic origins, reproductive pedigree, and agronomic characteristics. Currently, available research documents do not contain these data for varieties cultivated in the Sahel region. The modellization of crops has led to the development of more than 20 techniques for calculating the complex interactions between crops, soil types, temperature, and precipitation. However, these models provide only sufficient data to establish generalities about the characteristics of crops cultivated throughout the Sahel region. The modeling of the impact of climate change on crops in the Sahel region is currently limited by the lack of data. The adaptability of crops and their numerous varieties to the evolution of climatic conditions is extremely varied. Some crops are more tolerant of climatic variations, while the yield of others can decrease significantly if certain conditions are not met. This document is based on the main conclusions of the study: Del Rio, A., and Simpson, B. (2014). Agricultural Adaptation to Climate Change in the Sahel: A Review of Fifteen Crops Cultivated in the Sahel. USAID. Readers who wish to consult the document in its entirety are invited to visit the address: http://community.eldis.org/ARCC/.