Soil physical properties and organic matter govern available water in Inceptisols under different land uses

Understanding soil water availability is critical for sustainable land management in tropical agricultural systems, particularly in Inceptisols that often exhibit inherent physical constraints. This study aimed to evaluate the influence of soil physical properties and organic matter on available water under different land uses. The study was conducted in a representative Inceptisol landscape in Beji District, Pasuruan, Indonesia. Soil samples were collected from four land use types at two depths (0–30 cm and 30–60 cm), and key properties including bulk density, porosity, texture, and soil organic matter were analyzed along with soil water retention characteristics. The results showed that available water content was consistently low across all land uses, with values generally below 10%, and no significant differences were observed among land use types (p > 0.05). In contrast, soil properties exhibited significant relationships with available water. Soil organic matter and porosity were positively associated with water availability, whereas bulk density showed a negative relationship. Multiple regression analysis indicated that these variables jointly explained a substantial proportion of the variation in available water. These findings suggest that intrinsic soil properties, particularly soil physical characteristics and organic matter, play a more dominant role than land use in regulating water availability in Inceptisols. Improving soil organic matter may be more effective for enhancing soil water availability than changing land use.