The influence of a shift from conventional to organic olive farming on soil management and erosion risk in southern Spain

Natural resource conservation should be fundamental to organic agriculture, including the prevention of soil erosion. Soil erosion in the olive orchards of southern Spain is recognized as a serious problem causing environmental, economic and social repercussions, both on and off-site. This study describes the changes in soil management practices that accompanied a shift from conventional to organic olive farming and the corresponding effect of those management practices on erosion risk in the province of Córdoba, Andalusia. Interviews with 107 farmers were carried out in two different geographic areas to assess the socio-economic factors influencing farm management decision-making, and on-farm erosion risk evaluations and soil data (organic matter, aggregate stability, infiltration and vegetative ground cover) were taken on 25 farms to assess the effects of those decisions on soil erosion risk. Results from this study show that the shift to organic farming in olive orchards in the province of Córdoba has been accompanied by increased protection of the soil and lowered erosion risk. The most important changes in soil management practices associated with the transition from conventional to organic agriculture were the reduction in tillage and the increase in management systems that incorporate a vegetative cover controlled either by grazing livestock or mowing. However, the shift to organic farming has had more impact in the south of the province than in the north where farm management systems have historically led to less erosion.