Simultaneous changes in climate and management explain yield trends in a major maize system in Europe

Context: Meeting future food demand without massive land-use change will require faster rates of yield improvement. Although annual rates of crop yield gains have stagnated in some developed countries, the underlying causes are not clearly understood. Objectives: We assessed yield trends of irrigated maize in northern Italy since 2000 and investigated underlying climatic and technological factors influencing observed yield gains. Methods: We simulated yield potential using local weather data (2000–2023) assuming fixed and best available genetics to understand changes in yield due to climate. Additionally, historical data from new hybrids in wellmanaged maize cultivar trials and changes in management in farmer fields were analyzed to understand changes in yield due to genetic and agronomic improvements. Results: On-farm yield improvement has slowed substantially since 2000, with a rate of 54 kg ha⁻¹ y⁻¹ compared with 135 kg ha⁻¹ y-1 during the 1970–1999 period. Although yield potential has declined since 2001 (-142 kg ha􀀀 1 y-1) due to climate warming, average yields in farmer fields and cultivar trials have not decreased, implying that agronomic (e.g., increased plant density, pest management) and genetic adaptation have offset the negative impacts of climate change. However, neither genetics nor climate limits current yields as average farmer yield remains 32% below the yield potential estimated through crop modeling and cultivar trials. Conclusions: Climate warming has reduced maize yield potential in northern Italy, but agronomic and genetic improvements have largely offset the negative impact, with further yield gains still possible through improved agronomic management. Implications: Our methodology and findings are relevant for cropping systems around the world where yields are stalling in the context of climate warming.