Effects of terracing on soil properties in three key mountainous regions of China

Abstract Terracing greatly affects soil properties, ecosystem services, human welfare and geographical sustainability. The purpose of this article is to determine the influence of terracing on soil properties across diverse regions in China. Three representative terrace types, including dryland loess terraces, dry-stone terraces, and paddy terraces, were selected as case study areas. Soil sampling was stratified according to thickness of soil layers in each terraced area. Based on field investigations and soil sampling, combined with the means of variance, correlation, redundancy and regression analysis, we analyzed the characteristics of soil properties in the terraces across three areas. Results showed that: (1) alterations of soil physicochemical properties mainly depend on differences between soil parent materials in such regions; (2) Due to the existence of “four-element isomorphism” in the ecosystem and reasonable human activities, paddy terraces had the greatest impact on soil properties which is mainly reflected in decreasing soil pH and increasing SOC, TN, and TK; (3) The content of SOC and TN in different areas was higher in terraced fields than in the sloped lands and decreased with soil deepening; (4) To maintain sufficient supply of soil nutrients and support the sustainability of agricultural terraces, it is necessary to apply manure to improve soil fertility and accelerate its aggregation in the terraces. For example, an increase in the application of nitrogen fertilizer in terraced fields in Hebei and Gansu provinces, which have a serious deficiency in soil available phosphorus (AP), is necessary to get greater amounts of P fertilization. The present study offers a theoretical foundation for the sustainability of terraced ecosystems through efficient crop production, which is the basis for strengthening the ecological security of terraced areas and promoting regional sustainability in those fragile mountains.