Performance of major mechanized rainfed agricultural production in Sudan: Sorghum vulnerability and resilience to climate since 1970

摘要

Food security in the African Sahel has frequently been threatened by climate variability and change. A large part of the farming system in the arid and semi-arid region of Sudan is heavily rainfed, with sorghum representing the major crop. This studysheds light on the performance of sorghum production in the major mechanized sector in Sudan since 1970. Despite a significant extensification of the mechanized cultivated area of sorghum, a drastic loss of area at harvest took place during 1970-2016. The sorghum production showed both increases and decreases in the average over time besides high year-to-year variability. Synchronous with the above findings, a significant steady decline of sorghum yield occurred from the 1970s level (744.3 kg/ha) to 476.6 kg/ha since 1982. Based on the ratio of growing season precipitation to reference evapotranspiration, a Standardized Multi-Criteria Drought Index (SMCDI) for the period 1941-2015 was introduced using three drought characteristics, namely drought severity, dry spell and time relative frequency of drought. There occurred 23 mild to extreme droughts and 17 mild to extreme wet cases over the period 1970-2015. Aggregation of the SMCDI with ‘climatic’ sorghum yield revealed highly variable performance ofthis crop. Accordingly, 26 vulnerable and 20 resilient sorghum yield years were discernible under drought, near normal or wet conditions due to a combination of factors not only climate, i.e, physio-geographic, socio-economic and institutional factors.Apart from the regional analysis, one representative state was also selected for further in-depth spatio-temporal assessment of the SMCDI, integrated Normalized Difference Vegetation Index (iNDVI), Modified Vegetation Condition Index (MVCI), sorghum yield, precipitation and reference evapotranspiration data over the period 2001-2014. The results also underscored the spatio-temporal and local-scale vulnerability of the fanning system under study to climate variability. Such findings urge for interventions in the mechanized rainfed sorghum farming system to enable improvement of its performance, drought vulnerability reduction, development of alternatives, and achievement of food security.