Soil tillage reduction as a climate change mitigation strategy in Mediterranean cereal-based cropping systems

According to climate change projections, global temperatures would increase by 2 degrees C by 2070, and agriculture is expected to be among the most affected sectors, particularly intensive field crops like cereals. Therefore, researchers need to investigate the most cost-effective agricultural strategies that can prevent production losses and ensure global food security. This study aimed to identify the limiting factors of durum wheat (Triticum turgidum L. subsp. Durum (Desf.) Husn.) yield production under Mediterranean conditions. Durum wheat yield data of over 5 years (2017-2022), from a 30-year rainfed long-term experiment conducted in the 'Pasquale Rosati' experimental farm of the Polytechnic University of Marche in Agugliano, Italy (43 degrees 32' N, 13 degrees 22 ' E, 100 a.s.l.) on Calcaric Gleyic Cambisols with a silt-clay texture, were analysed and compared with the recorded thermo-pluviometric trend. The field trial included two soil managements (no tillage vs. conventional tillage) and three Nitrogen (N) fertilization levels (0, 90, and 180 kg N ha-1). The most important driver for durum wheat production was N fertilization. However, in the absence of N fertilization, no tillage showed a higher yield (+1.2 t ha-1) than conventional tillage due to the accumulation of organic matter in the soil. When wheat was fertilized with 90 kg N ha-1, no tillage resulted in 25% yield more than conventional tillage (+1.2 t ha-1), but this occurred only when the increase in temperatures was constant from January until harvest (this happened in 3 of 5 years of monitoring). The non-constant increase in temperature from January to wheat harvest may hamper crop phenological development and reduce the potential yield. The highest fertilization rate (180 Kg N ha-1) resulted in the highest wheat yields regardless of soil management and thermo-pluviometric trends (5.78 t ha-1). After N fertilization and soil management, the minimum and maximum temperature in February and the maximum temperature in April were crucial for durum wheat production under Mediterranean condition. When there is non-constant increase in temperature from January to wheat harvest no-tillage should be preferred over conventional tillage because wheat yields did not reduce under no tillage. Thus, agricultural policies that support the switch from conventional tillage to no-tillage management should be promoted to enable food security in Mediterranean environments.