Effect of biophysical soil and water conservation measures on physicochemical soil properties and their implications for climate resilience in degraded hillside landscapes of Tigray, Ethiopia

Soil erosion is a major driver of land degradation in mountainous semi-arid regions. In northern Ethiopia, integrated biophysical soil and water conservation (SWC) measures have been implemented to reduce erosion and improve soil quality. However, little is known about how these measures interact with slope position, soil depth, and proximity to conservation structures, limiting evidence-based strategies for optimizing SWC and promoting climate-resilient land management. This study assessed the effects of SWC on soil properties across slope positions, soil depths, and distances from SWC structures. 96 composite soil samples were collected using a factorial randomized complete block design: (i) management (treated vs. untreated) × slope position × soil depth × replication (48 samples) and (ii) distance from SWC structures × slope position × soil depth × replication (48 samples). Data analyzed using ANOVA with Tukey’s HSD in R (v4.2.3), at P < 0.05. Treated plots significantly improved key soil properties than untreated areas. Bulk density decreased by up to 6% in conserved plots (lowest 1.56 g/cm³ at lower slopes) versus untreated plots (highest 1.66 g/cm³ at upper slopes). Soil moisture content was 67% higher in treated lower-slope plots at 30–60 cm depth (7.99%) than in untreated upper-slope plots (4.77%). Water-stable aggregates increased by 28% in treated plots (64.03% at 0–30 cm depth) relative to untreated areas (50.16%). Interactions among management, slope, and soil depth were significant for moisture and aggregates (P < 0.001), indicating landscape-dependent SWC effectiveness. Soil organic matter correlated positively with available phosphorus (r = 0.648**, P < 0.01), total nitrogen, water-stable aggregates, and pH, and negatively with bulk density (r = -0.729**, P < 0.001). Results indicate that SWC plays a central role in improving soil fertility, structure, and water retention. These findings show that integrated SWC measures quantitatively enhance soil nutrient availability, reduce compaction, and improve moisture retention, providing a robust basis for vegetation recovery, productivity, and climate resilience in degraded hillside landscapes. While limited to short-term observations in selected sub-watersheds, longer-term monitoring across diverse sites, including biological, hydrological, and socio-economic factors, will strengthen evidence-based guidance for scalable, climate-resilient land management.