Effect of land use and management on the early stages of soil water erosion in French Mediterranean vineyards

The effect of changes in land use on the early stages of soil water erosion was studied on brown calcareous soils (Calcic Luvisols), a widespread type of soil suitable for wine-growing in the French Mediterranean area. This type of soil is subject to high intensity rainfall events. Rainfall of 60 mm/h was simulated on dry soil for several types of land use including scrubland, fallow and several wine-growing strategies (chemical and mechanical inter-row weeding, grassing, straw mulching, rock fragment cover and clearing rock fragments). l loss was observed for fallow and scrubland. The highest runoff rates and soil losses were observed for chemically weeded vineyards, with however, a reduction of soil losses when the prunings were left on the soil. Vineyards mulched with straw or with rock fragment cover were protected against runoff and soil erosion. As the grassing was recent, it was only partially effective, although several indicators showed that it might be promising in the future. A method of ranking the land uses in terms of protection against runoff and soil losses was derived from the experimental data. The statistical relationships between runoff, soil losses and various surface properties (soil cover including litter, weeds and rock fragments, crusts) and properties of the 0–5 cm topsoil layer (aggregate stability, carbon organic content, and porosity) were determined. The rate of initial crusts, the crusting with the rains, the aggregate stability, the carbon organic content and the soil porosity were significantly related to the runoff. The soil cover and the crusting with the rains were significantly related with the water turbidity. All theses parameters were significantly related to soil losses. However, runoff was poorly related to the water turbidity. The causality links between the results and the ranking of the land uses are discussed.