Despite almost a century of research and extension efforts, soil erosion by water, wind and tillage continues to be the greatest threat to soil health and soil ecosystem services in many regions of the world. Our understanding of the physical processes of erosion and the controls on those processes has been firmly established. Nevertheless, some elements remain controversial. It is often these controversial questions that hamper efforts to implement sound erosion control measures in many areas of the world.
Regional and global estimates of soil loss rates due to erosion differ substantially depending on the method used to derive them. Generally, estimates of mean annual soil loss from field plots are substantially higher (8 to almost 50 t ha-1 yr-1) than those from regional and global models (2 to 4 t ha-1 yr-1). Any estimate of erosion must also be placed in the context of the acceptable or tolerable rate of loss. Rates of tolerable soil loss calculated using soil production rates range from 0.2 to 2.2 t ha-1 yr-1 and tolerable rates based on maintenance of crop production range from approximately 1 to 11 t ha-1 yr-1. The ranges for both soil loss and tolerable soil loss demonstrate the need for site-specific estimates to reflect the different sensitivity of soils to removal of surface soil through erosion.
- Published: 2019
- Publisher: FAO
- ISBN-13: 978-92-5-131426-5