Resilience of conservation agriculture to rainfall deficits: A long-term study on durum wheat yield in Tunisia

Adopting climate-smart agriculture innovations, such as Conservation Agriculture (CA), is necessary in Tunisia to mitigate the impacts of climate change. The present study assessed the impact of CA on the resilience of durum wheat yield and water use efficiency (WUE) in the context of current climate change. The study involved a comparison of durum wheat yield stability and resilience over 12 successive years (from 2010 to 2022), between no-till (NT), minimum tillage (MT), and conventional tillage (CT), as influenced by precipitation and temperature variations across the crop cycle and year. The effect of tillage treatments on phenological stages (days to heading and grain filling duration) and soil organic carbon and nitrogen were assessed. Weather variables analysis revealed a significant decrease in precipitation and a significant increase in the number of rain-free days and temperature over the years. Results showed that durum wheat yield and aboveground biomass decreased over time in all three tillage treatments, but the rate of grain yield decreased differed significantly between the treatments. NT showed the smallest decrease rate in yield, followed by MT and CT, as well as the smallest coefficient of variation, indicating better yield stability. A highly significant relationship between weather variables and yield response ratios was observed, where the NT-to-CT ratio increased as precipitation decreased. Analysis of yields, soil water content, and phenology revealed that NT did not significantly outperform CT across all experimental years but showed a significant advantage only during years with low precipitation. Analysis of the relationships between variability in yield and variability in weather variables revealed that the NT system was less sensitive (more resilient) to changes in weather variables, especially with regard to the autumn and late spring precipitations. This is of great importance in emphasizing the necessity of the adoption of NT. The study demonstrated that the benefits of CA are particularly pronounced in years with extreme drought events, highlighting the importance of adopting such agriculture innovation to mitigate the impacts of changes in weather variables on durum wheat yield.