Soil lifespans and how they can be extended by land use and management change

Evans, Daniel and Quinton, John and Davies, Jessica and Zhao, Jianlin and Govers, Gerard (2020) Soil lifespans and how they can be extended by land use and management change. Environmental Research Letters, 15 (9). ISSN 1748-9326

Abstract

Human-induced soil erosion is a serious threat to global sustainability, endangering global food security, driving desertification and biodiversity loss, and degrading other vital ecosystem services. To help assess this threat, we amassed a global inventory of soil erosion rates consisting of 10,030 plot years of data from 255 sites under conventional agriculture and soil conservation management. We combined these with existing soil formation data to estimate soil sustainability expressed as a lifespan, here defined as the time taken for a topsoil of 30 cm to be eroded. We show that just under a third of conventionally managed soils in the dataset exhibit lifespans of <200 years, with 16% <100 years. Conservation measures substantially extend lifespan estimates, and in many cases promote soil thickening, with 39% of soils under conservation measures exhibiting lifespans exceeding 10,000 years. However, the efficacy of conservation measures is influenced by site- and region-specific variables such as climate, slope and soil texture. Finally, we show that short soil lifespans of <100 years are widespread globally, including some of the wealthiest nations. These findings highlight the pervasiveness, magnitude, and in some cases the immediacy of the threat posed by soil erosion to near-term soil sustainability. Yet, this work also demonstrates that we have a toolbox of conservation methods that have potential to ameliorate this issue, and their implementation can help ensure that the world's soils continue to provide for us for generations to come.