Spatial variability of soil compaction over a vineyard region in relation with soils and cultivation operations

Abstract

In the vineyard Languedoc plain soil compaction caused by tillage operations and traffic is suspected to have a long-term effect on vineyard production. To assess the importance of this soil compaction at the scale of a vine production area and to determine its various origins, a field method based on the morphological observation of the soil structure was applied at 28 sites that cover the variability of soils and vineyard operations within the Languedoc plain. Zones with a very high degree of compactness (Δ zones) were delineated in soil profiles and the origins of these zones were partly identified thanks to a set of rules considering the location of the Δ zones in the soil profile. The areas of Δ zones were summed at the site and at the regional scale to provide quantified indicators of soil compaction. The proposed method proved to be effective in assessing soil compaction at a regional scale, the delineated Δ zones exhibiting significant increases of bulk density. The results showed i) generally moderate levels of soil compaction with a few heavily compacted sites, ii) the equal predominance of compactions due to deep ploughing and traffic of tractors and their trailed tools, iii) the increase of soil compaction by deep ploughing in redoxisols in which wet conditions are more frequent, iv) the decrease of soil compaction by surface vineyard operations (tractor traffic, superficial tillage, harvesting) in case of grassed vine interrows.