Multi-year dynamics of soil quality and sorghum yield under conservation tillage in Northern Ethiopia

Global dry land agricultural systems face intensifying structural and climatic pressures, demanding innovative soil management paradigms to sustain crop productivity and preserve scarce hydrological and nutritional resources. Conventional tillage (CT) practices, characterized by intensive mechanical soil inversion, accelerate the oxidation of soil organic matter, disrupt macro-pore continuity, and generate high subsoil bulk density that limits water permeability and exacerbates terminal drought vulnerability. To address these systemic challenges, A five-year field study (2016–2020) was conducted at the Shire-May-Tsebri Agricultural Research Center in northern Ethiopia to assess the long-term impact of five tillage systems Zero Tillage (ZT), Mulch Tillage (MT), Reduced Tillage (RT), Strip Tillage (ST), and Conventional Tillage (CT) on topsoil properties and sorghum productivity. While the 2016 baseline season exhibited uniform initial soil parameters, progressive multi-year divergence established distinct structural equilibria over time. By 2020, continuous conservation management led to highly significant modifications in topsoil infrastructure ( P < 0.001). MT and ST maximized soil organic carbon accumulation to 2.34% and 1.89%, respectively, and drastically reduced bulk density down to 0.23 g/cm 3 and 0.42 g/cm 3 compared to the relatively higher BD under CT (0.89 g/cm 3 ). Two-way split-plot ANOVA confirmed that ST significantly preserved late-season soil profile moisture during terminal post-monsoonal drying phases, retaining a substantial hydrological reserve of 38.98% by November 2020. Agronomical, intensive mechanical inversion under CT optimized initial stand counts and functional heads but compromised the root microenvironment. Conversely, ST effectively bypassed early crop establishment barriers, achieving a stable intermediate plant population and unlocking an overwhelming 63.13% grain yield improvement over CT by the final 2020 season (51.99 kg/ha vs. 31.87 kg/ha). Pearson correlation analysis confirmed that final grain yield was profoundly coupled with late-season moisture retention ( r = 0.79) and organic carbon buildup ( r = 0.74). Ultimately, continuous Strip Tillage progressively rehabilitates dryland soil infrastructure, steadily elevating terminal water-use efficiency and providing a resilient climate-adaptation paradigm for dryland agricultural systems.