Multivariate Linkages Between Soil Health, Salinity Stress, and Wheat Yield Under Bio-Organic Management

Saline irrigation water is increasingly used in arid and coastal regions, posing serious constraints to soil health and wheat yield, particularly in saline–sodic soils. A two-season field experiment was conducted to evaluate the effects of compost, biofertilizers (Azospirillum brasilense and Azotobacter chroococcum), and their combinations on soil physicochemical properties, microbial activity, wheat growth, yield, and physiological traits under two irrigation water salinity levels (3 and 6 dS m−1). Two wheat varieties differing in salt tolerance (Miser 4 and Sakha 95) were tested. Salinity significantly increased soil EC and ESP and reduced plant growth, yield, and nutrient content, while integrated bio-organic treatments markedly alleviated these adverse effects. Compost combined with Azotobacter chroococcum markedly improved soil physical conditions, enhanced microbial biomass carbon, reduced sodicity indicators, and promoted wheat productivity across both seasons. Multivariate analyses including principal component analysis (PCA), redundancy analysis (RDA), and self-organizing maps (SOMs) revealed a strong positive association between yield traits, microbial activity, and soil fertility, and negative correlations with salinity stress indicators. The results demonstrate that combining compost with biofertilizers induces both immediate and residual improvements in saline–sodic soils, enhances wheat resilience to salinity stress, and offers a sustainable approach for improving cereal production under salt-affected environments.