Understanding the Role of Soils and Management on Crops in the Face of Climate Uncertainty in Zimbabwe: A Sensitivity Analysis

Although climate change is likely to affect a wide variety of sectors in Zimbabwe, the risk to agriculture stands out most since agriculture is the mainstay of the country’s economy. In addition, there is little information available on how to help smallholder farming systems and livelihoods respond to these risks. To determine the effects on crop production of expected changes in precipitation patterns and projected increases in carbon dioxide (CO2) and temperature, we used two process-based crop models—the Decision Support System for Agrotechnology Transfer (DSSAT) model and the Agricultural Production Systems Simulator (APSIM) model. The models were calibrated and validated to assess the effects of single and combined climatic factors on grain and stover yield performance of maize and groundnut, across three soil types. The two models generally agree on the effects that different climatic factors have on both maize and groundnuts, however, the magnitude of the effects varied. For example, reductions on maize grain yields are more pronounced in the APSIM model while the DSSAT model shows more pronounced reduction of maize stover yields. Both models show yield benefits under elevated CO2 concentration for groundnuts negating the effects of increased temperatures when evaluating the combined effects of the climatic factors. However, yield increases for both groundnut grain and stover are more pronounced in the DSSAT model. The key finding is that soils play an important role in determining outputs of crop-climate interactions: they can buffer or aggravate climatic impacts.