Review on the effects of ridge pattern and ridge-furrow intervals on soil erosion of sloping farmland in the black soil region

Abstract: Black soil can be one of the most fertile soil groups with relatively high carbon stocks and production capacity. The black soil region can also play an important role in national food security and sustainable development in China. However, overexploitation and utilization have caused serious soil erosion in the black soil region of northeast China in recent years. There is a direct impact of the difference in tillage pattern on the soil erosion characteristics of sloping farmland. Fortunately, ridge farming can be commonly used in the tillage pattern. Furthermore, the ridge-furrow intervals with less amount of soil movement can also be used without occupying the farmland in this region. Therefore, it is of great significance to accurately evaluate the suitable measures of soil and water conservation. In this study, a systematic review was proposed to clarify the effects of ridge direction, ridge size, and ridge-furrow intervals on the soil erosion characteristics of sloping farmland in the Chinese black soil region. Furthermore, the relationship among the ridge patterns, the ridge-furrow intervals, and soil erosion was then established to determine the key fields to be strengthened in future studies for the major challenges. The results indicated that the pattern of longitudinal ridge-tillage was still the most common-used tillage pattern. The soil erosion gradually deteriorated to shift the soil erosion types from sheet to rill erosion, leading to less soil quality and crop yield. A better way was found to control soil erosion in the general patterns of contour ridge-tillage and sloping ridge-tillage, which was closely related to ridge failure. Among them, the pattern of sloping ridge-tillage was more likely to occur the ridge failure. Once the ridge failure occurred, the soil erosion increased significantly, even much more than that of the pattern of contour ridge-tillage. Thus, the pattern of contour ridge-tillage can be expected to effectively decrease the soil erosion at the sloping farmland in the black soil region. Furthermore, the pattern of the narrow ridge is also commonly used in the black soil region of northeast China in the long term. Therefore, it is very necessary to determine the effects of narrow ridges and their operation patterns on soil erosion. The pattern of the wide ridge is widely used in large-scale intensive farms and rural cooperatives, rather than individual farms, due to the outstanding control effect on the soil erosion for the high crop yield. Thus, it is a high demand for wide ridges among the individual farms in the future, in order to protect the precious black soil resources. The control effect of the ridge-furrow intervals pattern on the soil erosion depended mainly on the rainfall amount, rainfall intensity, slope gradient, ridge size, and the spacing of the ridge-furrow intervals. Therefore, it is suggested that the pattern of ridge-furrow intervals is gradually applied to the sloping farmland in the black soil region, in order to separate the layout, and then cooperate with the wide ridge, slope terrace, plant hedge, subsoiling, and straw return. The optimal allocation mode can be further improved the better measures of the composite soil and water conservation for less soil erosion. Much effort was also made into the effects of tillage patterns on the soil erosion of sloping farmland in the black soil region. Nevertheless, the technical conditions can still be limited to systematic research in this field. As such, the future directions can be proposed to analyze the influencing mechanism of ridge patterns, the coupling relationship between ridge direction and ridge size, the ridge design for the pattern of ridge-furrow intervals, and the comprehensive factors analysis of the effect of ridge pattern on the soil erosion in the sloping farmland. In conclusion, the systematic research is very necessary to focus on the effects of ridge patterns and ridge-furrow intervals on soil erosion at the sloping farmland in the black soil region.