Abstract: 【Objective】The objectives of this paper were to study the spatial distribution characteristics of soil surface elevations and roughness caused by the tillage treatments and to investigate the changes in soil surface elevations and roughness after rainfall, so as to deeply understand the effects of tillage treatments and rainfall intensities on spatial distribution of soil surface elevations and soil surface roughness (SSR). 【Method】 The experiment was arranged in completely randomized block design, with three replications for each treatment. The size of soil box was 2.0 m in length, 1.0 m in width and 0.5 m in depth. The gradient of soil box was 18%. The tillage treatments used were artificial shallow plowing (ASP), artificial deep plowing (ADP), contour plowing (CP), and no treatment (CK). Three rainfall intensities (60 mm·h^-1, 90 mm·h^-1 and 120 mm·h^-1) were applied to conduct the rainfall, and rainfall duration was 90 minutes. Soil surface elevations in soil box were measured using a laser scanner before and after rainfall to analyze the changes of elevation and SSR. 【Result】 There was a significant difference in spatial distribution of elevations among these four tillage treatments. Statistical variance of surface elevations of CK was the lowest compared with ASP, ADP and CP, including the spatial distribution of elevation of CK was the highest concentration than the others. While statistical variance of surface elevations of CP was the highest compared with ASP, ADP and CK, suggesting the spatial distribution of surface elevations of CP was the most dispersion one. Spatial distribution of surface elevations of ASP and ADP were the median. Before the rain, the order of SSR value was CP＞ADP＞ASP＞CK. This implied that deep ploughing treatment caused severer changes in SSR than shallow ploughing treatment. SSR value changed apparently after rainfall. And the changes of SSR aggravated as rainfall intensity increased under the same tillage treatment. After rainfall, SSR of CP, ADP and ASP were decreased compared to SSR of them before the rainfall. For one certain rainfall intensity, SSR decrease was the greatest for CP, the medium for ADP and the lowest for ASP. But SSR of CK increased a few rather than decreased under the same rainfall intensity condition. It increased 10.9%, 22.5% and 36.5% of 60, 90 and 120 mm·h^-1 rainfall intensity, respectively. Although rainfall event changed SSR, the order of SSR was still CP＞ADP＞ASP＞CK after rainfall. This suggests rainfall event changed the value of SSR but it did not change the spatial distribution characteristics of SSR. The effects of CP, ADP and ASP tillage treatments on SSR were dominated while the effects of rainfall on SSR were subordinated. Regression equations between change rate of SSR (ΔSSR) and rainfall intensity were obtained for each tillage treatment. 【Conclusion】 Tillage treatment was the most important factor to form soil surface roughness on sloping farmland. The spatial heterogeneity of SSR caused by tillage treatments was as follows: different tillage activities caused different soil surface disturbance and led to different soil surface spatial structural and distribution patterns. Rainfall increased SSR of CK while decreased SSR of ASP, ADP and CP. The greater initial SSR value was, the more significant SSR value changed. The change of SSR severed as rainfall intensity increased under the same tillage treatment. However, the influence of ASP, ADP and CP tillage treatments on SSR were stronger than influence of rainfall on SSR.

Key words: elevation, soil surface roughness, tillage treatments, rainfall intensity