Physical and chemical soil quality indicators in a minimum dataset: discriminating management effects in saline Entisols and Aridisols under hyper-arid conditions

Context Soil salinisation and sodicity severely limit agricultural sustainability in hyper-arid environments. Over 833 million hectares are affected globally, yet soil quality assessments rely predominantly on chemical indicators, neglecting physical properties governing pore architecture, water availability, and structural stability. Aims To identify sensitive physical and chemical indicators for saline soils, establish a minimum dataset, and construct a soil quality index (SQI) capable of discriminating management effects in saline Entisols and Aridisols. Methods Twenty physical and chemical properties were measured in Entisols and Aridisols of the Atacama Desert, Chile, across four contrasting management systems from degraded fallow to permanent vegetation cover. Principal component analysis, correlation analysis, and sensitivity criteria guided indicator selection; selected indicators were normalised using linear scoring functions and integrated into an additive SQI. Key results Five indicators were selected: exchangeable sodium percentage, pH, clay + silt, available water capacity, and micropore/macropore ratio, the latter a novel structural indicator rarely included in saline soil quality frameworks. The SQI values ranged from 1.22 (degraded cultivation) to 4.93 (permanent olive cover). Thresholds of 2.5 and 4.0 delineated severely degraded, transitional, and functionally restored soils. Permanent vegetation showed the highest SQI values. Conclusions Sodicity, texture, and pore architecture jointly control soil quality in saline hyper-arid systems. The micropore/macropore ratio proved a sensitive structural indicator of management-induced changes across contrasting soil orders. Implications The SQI supports restoration strategies based on permanent vegetation and organic amendments in salt-affected drylands, with low analytical cost and transferability to other arid regions affected by salinisation.