Understanding soil erosion processes in Mediterranean sloping vineyards (Montes de Málaga, Spain)

- Bare soils induced high soil erosion rates in sloping vineyards.
- 25 natural rainfall events were assessed using six Gerlach troughs.
- Runoff threshold was very low with a large range (between 4.55 mm and 8.5 mm).
- The highest soil loss and overland flow were obtained in a few rainfall events.

Sloping vineyards in the Mediterranean cultivated on bare soils show several types of evidence of soil erosion processes. However, little is known about the key factors that condition and enhance these processes at the intra-plot scale. There is a need to assess soil conservation methods to reach sustainability of vineyards and high grape quality, and for this it is necessary to investigate the factors and rates of soil erosion processes under natural conditions. The main goal of this research, conducted in traditional Mediterranean vineyards in Los Montes de Málaga (South Spain), was to carry out a precision analysis of the patterns of soil erosion and the soil surface components at the intra-plot scale. The analysis was performed after monitoring soil erosion processes during 25 natural rainfall events. Soil loss, overland flow, and runoff threshold were calculated using six Gerlach troughs. Fine soil particles and rock fragments were also assessed after each natural rainfall event and tillage practice. The research showed an example of sloping vineyards in a Mediterranean environment with bare soils that are associated with high soil losses and an uneven spatiotemporal distribution of hydrological and geomorphological processes. Key factors enhancing soil erosion processes are: i) extreme rainfall events and ii) management practices (pruning, ploughing and trampling). The runoff threshold reached very low values (between 4.55 mm and 8.5 mm) and the highest soil loss and overland flow rates were obtained from a few rainfall events during the rainiest period, coinciding with times that the surface was covered by vines that had dropped their leaf cover. Finally, we demonstrated that the runoff threshold, soil loss and overland flow showed high variability depending on the stoniness, soil texture, and antecedent conditions of tillage.