Effect of deep tillage for vineyard establishment on soil structure: A case study in Southern France

Deep tillage that is used before vine plantation to remove old vine roots and loosen subsoil may induce physical soil degradation that could affect soil structure and vine water supply. The objective of the study was to experimentally evaluate the effect of deep tillage on soil structure. The impacts on soil structure of two deep tillage techniques, i.e. deep ploughing and ripper, and two contrasted soil water conditions were compared in a experimental field by combining morphological observations, bulk density and saturated hydraulic conductivity measurements. These three methods were found very complementary to analyse and discriminate the impact of the different treatments. The proportion of compacted zones and mean bulk density increased from the initial plot (0.15 m2 m−2, 1.45 Mg m−3) to a maximum in the case of the deep ploughing under wet conditions plot (0.60 m2 m−2, 1.60 Mg m−3). The main results showed that (i) a significant soil compaction was observed after wet conditions only, (ii) deep ploughing produced more soil compaction than ripper because of a greater volume of soil affected by wheeling in the former operation and (iii) a specific response of soils is significatively observed in the case of deep ploughing only with an increase of compacted zones fragmentation in relation to a decrease of clay content.