Magnetized Saline Water Modulates Soil Salinization and Enhances Forage Productivity: Genotype-Specific Responses of Lotus corniculatus L.

Irrigation water salinity poses escalating threats to agricultural sustainability in degraded agroecosystems. This study has investigated the effects of magnetized versus non-magnetized saline water on the soil physicochemical properties and forage productivity of three Lotus corniculatus L. genotypes (salt-sensitive ecotype 232098, moderately salt-tolerant San Gabriel, and salt-tolerant Estanzuela Ganador) in arid northern Mexico. A split-plot randomized block design with three replicates assigned saline water treatments (magnetized [MWT] vs. non-magnetized [NMWT]) to main plots and genotypes to subplots. After one year of irrigation, MWT significantly attenuated soil salinization, evidenced by 23% lower electrical conductivity (5.8 vs. 7.2 dS·m⁻1), a 26% reduced sodium adsorption ratio (6.2 vs. 8.4), and a 41% decreased sodium concentration (20.7 vs. 35.4 meq·L⁻1) compared to NMWT (p < 0.05). Although agronomic traits (stem dimensions, leaf area index, and rhizome proliferation) exhibited salt sensitivity from the third season onward, fresh biomass yield remained unaffected by water treatment. Genotypic differences dominated productivity. Estanzuela Ganador achieved superior biomass in both seasons (288.9 g/rhizome in fall; 184.2 g in winter), outperforming San Gabriel by 15.8% and ecotype 232098 by 56.8% (p < 0.05). These findings demonstrate that magnetized saline water irrigation effectively mitigates soil salinity progression, while genotype selection critically determines forage productivity under arid conditions. Estanzuela Ganador emerges as the optimal cultivar for saline irrigation systems in water-scarce regions.