Application of crop residues (mulch) over the soil surface is a common practice to control soil erosion and promote infiltration. This laboratory study aimed at investigating the effect of different rice straw mulch sizes on runoff and sediment transport. The experimental runs were conducted using a soil flume of adjustable slope and a rainfall simulator, considering bare soil and three different soil covers: 1, 2 and 5 t ha⁻¹ application rates, for three sizes of rice straw mulch (10, 30 and 200 mm). The experimental results showed that for the same mulch application rate (by weight), the smaller mulch sizes (i.e. high surface coverage percentage) presented less soil loss. For example, 90 % soil loss reduction was achieved for smaller sizes of rice straw mulch and 80 % for the bigger size. The results of this study are an important contribution to the understanding of the soil loss process in small basins and to the definition of relevant soil conservation measures, at the plot/field scale.

The role of stony soils in runoff response of mountain catchments is rarely studied. We have compared simulated response of stony soils with measured catchment runoff for events caused by rains of small and high intensities in the mountain catchment of the Jalovecký Creek, Slovakia. The soil water response was simulated for three sites with stoniness 10–65% using the Hydrus-2D single porosity model. Soil hydraulic parameters employed in the modelling, i. e. the saturated hydraulic conductivity and parameters of the soil water retention curves, were obtained by two approaches, namely by the Representative Elementary Volume approach (REVa) and by the inverse modelling with Hydrus-1D model (IMa). The soil water outflow hydrographs simulated by Hydrus-2D were compared to catchment runoff hydrographs by analysing their skewness and peak times. Measured catchment runoff hydrographs were similar to simulated soil water outflow hydrographs for about a half of rainfall events. Interestingly, most of them were caused by rainfalls with small intensity (below 2.5 mm/10 min). The REV approach to derive soil hydraulic parameters for soil water outflow modelling provided more realistic shapes of soil water outflow hydrographs and peak times than the IMa approach.