The Impact of Land-Use on the Hierarchical Pore Size Distribution and Water Retention Properties in Loamy Soils

Soil hydraulic properties are very sensitive to land-use in regions susceptible to physical degradation. Intensive agricultural practices often lead to soil compaction and erosion in the investigated area. The main goal of this paper was to evaluate the impact of land-use on the pore size distribution and water retention in loamy soils. The soil water retention curve (SWRC) combined the total porosity and the water retention of the undisturbed sample at 3, 10, 31, 100, 310, and 1000 hPa suctions and the disturbed sample at 1.5 MPa. The triple-exponential model approximated the curve's course, and its derivative defined the distinct macro-, structural, and textural pore maxima, with characteristic suctions corresponding to SWRC inflection points. The soil organic carbon content had the greatest influence on the content of all three pore classes. The water retention properties followed the hierarchical pore size distribution in the four research plots and decreased in the identical orchard > forest > grassland > arable soil order. These results show that the orchard and forest areas are the most appropriate land uses with respect to porosity and water retention, while the grassland has not fully recovered after its conversion from arable soil and remains relatively poor, and the arable soil properties are the worst.