Effect of gravel content on soil water retention characteristics and thermal capacity of sandy and silty soils

Abstract The presence of gravel in soils modifies the porosity, pore connectivity and size distribution soil matrix as well matrix-gravel interfaces. aim present study is to investigate effect relative volume samples with mass fractions 5,10, 20 wt% varying bulk densities (1.3, 1.45, 1.55, 1.60, 1.65 g cm –3 ) on (i) total field capacity, plant available water holding (ii) (iii) thermal capacity repacked sandy silty soils. focus was determine if laboratory measured retention curves considering (i), (ii), can be predicted by a gravel-based weighting factor, R v , comprehensive significance tests. sand-gravel mixtures show decrease macropores wide cores pores an increase contents, while silt-gravel opposite trend. root mean square errors (RMSE) between fitted volumetric θ, 0.006 0.0352 0.002 0.004 for -weighted contents indicate that van Genuchten-based Peters-Durner-Iden (PDI) model appropriate fitting. up 10 silt sand factors (relative rock fragments) range 0.045 0.058 silt, 0.112 0.119 sand. results also Rv-weighted saturated, c vsat dry, vdry both Further investigations are needed examine whether sand- below % or rather factor.