INFILTRATION CHARACTERISTICS OF SOILS IN MEDITERRANEAN VINEYARDS IN SOUTHERN FRANCE

This study examines factors affecting the spatial variability of soil infiltration in cultivated fields in a Mediterranean environment. The study area is a wine growing catchment located near the town of Roujan (Herault) in the South of France. The steady state infiltration rate was measured in 1 m(2) plots in a sample of eight untilled vineyards, using a rainfall simulator. Five measurements were made in each field in order to assess the between- and within-field variability of infilt ration. The factors affecting variability of soil infiltration (field effect, slope, soil type, structure of the first few centimetres of th e soil, roughness, texture, grass cover and surface water content) wer e analyzed. A simple classification of the topsoil structures is propo sed. Analyses of variance were carried out as a first step, to test th e effect of these factors on infiltration in all measurement plots. An attempt was made to simplify these results by grouping together field s with homogeneous characteristics. The results show that 40% of the t otal variance of observed infiltration rates can be explained either b y differences between fields or by differences in local topsoil struct ure. The latter two criteria are easily observable and can therefore b e used in practice for stratifying the spatial variability of infiltra tion rates. (C) 1998 Elsevier Science B.V. All rights reserved.