Search Results (3)

The Loess Plateau of China, a region highly vulnerable to erosion and climatic variability, faces significant soil degradation exacerbated by intensive agricultural practices and anthropogenic pressures. This study investigates the impacts of incremental soil compaction (P1–P5) on hydraulic properties, pore structure, and water retention across distinct soil textures (sandy loam, loam, clay loam) to address gaps in understanding texture-specific resilience and soil organic carbon (SOC) interactions. Utilizing X-ray computed tomography (CT), soil water retention curve (SWRC) analysis, and the van Genuchten (vG) model, we quantified compaction-induced changes in porosity, connectivity, and hydraulic conductivity, while comparing unsaturated hydraulic conductivity (Kun) predictions derived from mini disc infiltrometer (MDI) and SWRC parameters. Results revealed that fine-textured, SOC-rich soils had greater compaction, preserving macropore connectivity and saturated hydraulic conductivity (Ks), whereas sandy soils pronounced macropore collapse. Compaction homogenized pore distributions, steepened SWRC, and reduced plant-available water. Integration of CT and SWRC methodologies highlighted CT sensitivity to air-filled macropores versus SWRC’s focus on water-retentive micropores. Strong correlation (R² = 0.94–0.99) between vG parameters from MDI and SWRC validated parameter robustness, though MDI slightly underestimated Kun in clay loam, while SWRC-based models aligned closely with observed data. Integrating CT and SWRC methodologies offers a framework for precision soil health monitoring. In addition to the critical role of SOC and texture in compaction mitigation, there is a need for organic amendments in sandy soil and reduced tillage. Full article

Disc infiltrometers are used to characterize soil hydraulic properties. The purpose of this study was to determine the difference between three- and one-dimensional infiltration and to calculate the infiltration shape parameter γ from a proposed analytical infiltration equation. One- and three-dimensional infiltration tests were done on three repacked soils (loam, sandy loam, and silty clay loam) for two negative pressure heads. A mini disc infiltrometer of a radius of 22.5 mm with suction that ranged from −5 mm to −70 mm was used. The difference between experimental three- and one-dimensional cumulative infiltration was linear with time, which confirmed the proposed equation. In this study, the shape parameter γ seems not to be seriously affected by the soil type and acquires values from 0.561 to 0.615, i.e., smaller than the value γ = 0.75, which is widely used. With these values, the criteria proposed for calculating hydraulic conductivity using three-dimensional infiltration data may be fulfilled in most soils. Full article

Disc infiltrometer experiments were conducted in the laboratory on two disturbed soils, a loam and a silty clay loam soil, in order to investigate the relationship between three- and one-dimensional infiltration using the proposed equation of Smettem et al. A mini disc infiltrometer of a radius of 45 mm with suction ranged from −5 mm to −70 mm was used. Three- and one-dimensional infiltration tests were performed on repacked cores by applying pressure heads −70, −40 and −10 mm for loam soil, and −30 and −10 mm for silty clay loam soil. Analysis of the results showed that the difference between the three- and one-dimensional infiltration is linear with time confirming the equation of Smettem et al. [1]. Also, this difference is used to calculate the value of an additional infiltration parameter. Full article