Advantages and disadvantages of terracing: A comprehensive review

For thousands of years, terracing has been one of the most important systems for preventing soil erosion, conserving water, and increasing agricultural production. Despite having a long history, the wide-ranging effects and mechanisms of terracing are poorly understood owing to large-scale spatial and temporal distribution patterns and the challenges related to assessing the ecosystem services of terraced landscapes. Thus, our study aims to review comprehensively the effect of terraces by describing the mechanisms behind terraced systems. Terraces provide many ecosystem services, including the reduction of runoff and sediment by over 41.9% and 52%, respectively, and the improvement of grain yields and soil moisture content by 44.8% and 12.9%, respectively. In addition, terracing can also contribute toward the conservation of plant biodiversity on a local scale. However, as terraces age, a number of disadvantages gradually emerge, including interference with water circulation and the development of serious environmental problems caused by poorly designed or mismanaged terraces, where the average runoff and soil loss can be 1–5 times that of well-managed terraces. Although understanding the complexity and multifaceted effects of terracing is vital for terrace construction and management, the negative effects of terracing are often not considered, and existing studies have several shortcomings. Within this context, this paper aims to describe both the benefits and disadvantages of terracing, investigate the gaps in current research, as well as discuss preventive and remedial measures so as to negate the possible bad impacts of terracing.