Abstract
<title>Abstract</title> <p>The increasing use of recycled water for irrigation requires reliable indicators to assess potential impacts on soil physical properties. Traditional irrigation water quality assessments rely primarily on the Sodium Adsorption Ratio (SAR) to evaluate soil permeability hazards; however, SAR does not account for the potential dispersive effects of potassium or differences in the flocculating roles of calcium and magnesium. This study evaluated the influence of irrigation water cation composition on soil structural stability using a greenhouse experiment with strawberry plants irrigated with synthetic recycled waters of contrasting cation ratios. Standing water occurrence, relative infiltration rate, clay dispersion and volumetric soil water content were monitored to assess soil physical responses. Irrigation with waters dominated by dispersive cations increased drainage impairment, reduced relative infiltration and promoted clay dispersion compared with calcium-dominated treatments. Clay dispersion was strongly associated with irrigation water cation composition and appeared to be the primary mechanism driving soil structural degradation. Among the evaluated indices, the Cation Ratio of Soil Structural Stability (CROSSf) showed stronger relationships with soil physical indicators than SAR. These results are consistent with previous laboratory column experiments and confirm that CROSSf provides improved predictions of soil permeability hazards under cropping conditions. Incorporating indices such as CROSS into irrigation water quality assessment frameworks may improve the management of agricultural systems increasingly relying on recycled water.</p>