Evaluation of hydrological properties of gypsiferous soils cultivated with wheat under varying gypsum content

Gypsum-rich soils are widespread and play a significant role in agricultural productivity and water management, especially in arid and semi-arid regions. Understanding the effect of gypsum content on soil water movement is essential for optimizing irrigation and soil conservation in wheat-based systems. This study, conducted on wheat-cultivated soils under field conditions, aimed to evaluate key hydrological properties across varying gypsum levels. The gypsum levels in the studied soils were 45, 92, 156, 248, 468 and 583 g kg-1. Field infiltration rates were measured using the double-ring infiltrometer method and sorptivity was estimated using standard infiltration models. Saturated hydraulic conductivity (Ks) was also determined for each soil type. The pattern of cumulative infiltration generally mirrored the upward trend in Ks, underscoring the close relationship between infiltration dynamics and saturated hydraulic conductivity. Cumulative infiltration varied irregularly with gypsum content, ranging from 1.4 to 8.7 cm. Results showed a general increase in saturated hydraulic conductivity with increasing gypsum content, likely due to enhanced soil structure and macroporosity at higher gypsum levels. The Philip and Smith & Knight models provided more consistent predictions of water movement over longer infiltration times. The findings highlight the importance of gypsum content as a key factor influencing soil water behavior and provide insight into selecting appropriate models for estimating infiltration parameters. These results are particularly relevant for irrigation design and soil management in wheat cultivation on gypsiferous soils.