Applying a simple methodology to assess historical soil erosion in olive orchards

Although soil erosion is a well-known problem in olive orchards, causing both on-site soil degradation and off-site environmental pollution, quantitative field measurements of soil erosion are scarce. This situation has restrained the development of a reliable, predictive soil erosion model for this land use. This study applies a simple and inexpensive technique to measure soil losses in olive orchards over a medium-term time scale. The methodology is based on measuring the size of small mounds that form around individual trees. The resulting historical soil loss rate, averaged for seven sites and over a period between 55-100 years, was 95 Mg ha(-1) yr(-1). Locally, the historical soil loss rate amounted up to 184 Mg ha(-1) yr(-1). The measurement of actual erosion by water yielded a soil loss rate between 70-100 Mg ha(-1) yr(-1). This difference illustrates the important contribution of tillage translocation. Our approach provides novel insights into the intensity and processes of soil erosion in olive orchards. It also provides valuable input for model calibration and validation. (C) 2009 Elsevier B.V. All rights reserved.