Modelling the potential impact of climate change on sorghum and cowpea production in semi-arid areas of Kenya using the agricultural production systems simulator (APSIM)

Managing crop production risks associated with inter-annual climate variability and climate change has received insignificant attention in the semi-arid areas of Kenya. Against this backdrop, the potential impact of climate change on sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata) production in the semi-arid areas of Kenya will be assessed using the Agricultural Production System Simulator (APSIM). The study will employ participatory tools in the use of APSIM model to identify risks and cropping system improvement options and designing cropping strategies for field experimentation. The field experiments will be conducted in Makueni district of Eastern Province, Kenya. Initially, a farmers’ workshop will be held to gather information on farmers’ experience with recent climatic changes and possible causes, effect on current farming systems, coping and adaption strategies to current management practices. Farm households’ perceptions of risks, options to reduce climatic risks, specific vulnerabilities of the current cropping systems and coping strategies will be documented using semi-structured interviews during farm surveys. This is in addition to establishing the socio-economic and agricultural systems setting of the smallholder farmers. Potential technologies to address the anticipated negative impacts of climate change in respect of cowpea (legume) and sorghum (cereal) cropping system will jointly be identified with the farmers and a subset of tactical adaptation options identified. The options will initially be tested on-station in the first year and on farm in the second year. The on station experiments will be conducted for two (four seasons) years to model sorghum and cowpea growth and soil-water, soil organic carbon and nitrogen dynamics in a legume-cereal cropping system. The APSIM model will be validated to simulate both the legume and cereal components of the cropping system. The integrity of the simulated system will be evaluated by comparing the simulated performance of the crops with actual experimental crop data and by exploring other facets such as water use, denitrification and leaching. It is envisioned that the APSIM model will allow for quick exploration of production outcomes of a range of management alternatives under a range of climatic scenarios (realized or predicted), and for a range of soil conditions. This is in addition to provision of valuable information for evaluating a wide range of cropping system options.