Terroir 2008 banner
IVES 9 IVES Conference Series 9 Contribution of Electrical Resistivity Tomography (ERT) measurements for characterizing hydrological behaviour of an experimental plot in relation to pedo-geological factors (AOC Gaillac, SW France)

Contribution of Electrical Resistivity Tomography (ERT) measurements for characterizing hydrological behaviour of an experimental plot in relation to pedo-geological factors (AOC Gaillac, SW France)

Abstract

Electrical Resistivity Tomography (ERT) measurements have been performed by the Wenner method on an experimental plot situated in Gaillac region. They have been carried out during two highly contrasted hydric periods: (i) dry (spring 2006), (ii) humid (spring 2007) with soils close to field capacity. Results are compared to evaluate the hydrological behavior of the plot in relation with its main pedo-geological characteristics. The three reiterated transects (North-Median-South) give a general view of the plot configuration in agreement with the pedo-geologic observation trenches data. All the resistivity profiles show the superposition of two highly contrasted sequences. The first sequence, at the bottom, is a very low resistivity values sequence (up to 40 Ω.m) which coincides with the argillaceous-dominated molassic bed-rock. The second is a high to very high resistivity values sequence (from 300 Ω.m to more than 1500 Ω.m at the very top) which coincides with a silty-sandy and gravels soil complex of about 2 m thick. Resistivity of the molassic clayed-dominated geological basement does not depend on climatic conditions and stays at a very low value independently of dry or humid periods. Resistivity values of the silty-sandy/gravels horizons vary with a factor 2, from 300 to 750 Ω.m in humid conditions and from 750 Ω.m to 1500 Ω.m under dry conditions. Furthermore, the invariant location in the resistivity profiles of the two sequences, implies that the water runoff at the molassic bed rock/gravels interface is short-lived and most probably of low amplitude.
The hydric behavior of the experimental plot evidences a high risk of drought stress during summer. The choice of a rootstock with a hemi-plunging habit (Gravesac) will allow roots to attain the moisture at the molasse/gravels boundary and protect them from excess of drought.

DOI:

Publication date: December 8, 2021

Issue: Terroir 2008

Type : Article

Authors

Pierre COURJAULT-RADÉ (1), José DARROZES (1), Muriel LLUBES (2), Eric MAIRE (1), Marguerite MUNOZ (1) and Nicolas HIRISSOU (3)

(1) Laboratoire des Mécanismes de Transfert en Géologie (LMTG) – Université de Toulouse – UMR 5563 – CNRS – 14, Avenue E. Belin 31400 Toulouse (France)
(2) Laboratoire d’Etudes en Géophysique et Océanographie Spatiales (LEGOS)- Université de Toulouse – 14, Avenue E. Belin 31400 Toulouse (France)
(3) Domaine du Moulin, Chemin de Bastié, 81600 Gaillac (France)

Contact the author

Keywords

AOC Gaillac, Fonctionnement hydrique, Pédo-géologie, Résistivité, Sud-Ouest France

Tags

IVES Conference Series | Terroir 2008

Citation

Related articles…

Revealing the Barossa zone sub-divisions through sensory and chemical analysis of Shiraz wine

The Barossa zone is arguably one of the most well-recognised wine producing regions in Australia and internationally; known mainly for the production of its distinct Shiraz wines. However, within the broad Barossa geographical delimitation, a variation in terroir can be perceived and is expressed as sensorial and chemical profile differences between wines. This study aimed to explore the sub-division classification across the Barossa region using chemical and sensory measurements. Shiraz grapes from 4 different vintages and different vineyards across the Barossa (2018, n = 69; 2019, n = 72; 2020, n = 79; 2021, n = 64) were harvested and made using a standardised small lot winemaking procedure. The analysis involved a sensory descriptive analysis with a highly trained panel and chemical measurement including basic chemistry (e.g. pH, TA, alcohol content, total SO2), phenolic composition, volatile compounds, metals, proline, and polysaccharides. The datasets were combined and analysed through an unsupervised, clustering analysis. Firstly, each vintage was considered separately to investigate any vintage to vintage variation. The datasets were then combined and analysed as a whole. The number of sub-divisions based on the measurements were identified and characterised with their sensory and chemical profile and some consistencies were seen between the vintages. Preliminary analysis of the sensory results showed that in most vintages, two major groups could be identified characterised with one group showing a fruit-forward profile and another displaying savoury and cooked vegetables characters. The exploration of distinct profiles arising from the Barossa wine producing region will provide producers with valuable information about the regional potential of their wine assisting with tools to increase their target market and reputation. This study will also provide a robust and comprehensive basis to determine the distinctive terroir characteristics which exist within the Barossa wine producing region.

First step in the preparation of a soil map of the Protected Designation of Origin Valdepeñas (Central, Spain)

This work is a first step to make a map of vineyard soils. The characterization of the soils of the Protected Designation of Origin (D.P.O.) Valdepeñas will allow to group the studied profiles according to their physico-chemical characteristics and the concentrations of most relevant chemical elements. 90 soil profiles were analysed throughout the territory and the soils were sampled and described according to FAO (2006) and classified according to and Soil Taxonomy (2014). All samples were air dried, sieved and some physico-chemical parameters were determined following standard protocols. Also, major and trace elements were analysed by X-ray fluorescence. The statistically study was made using the SPSS program. Trend maps were made using the ArcGIS program. The studied soils have the following average properties: pH, 8.3; electrical conductivity, 0,20 dS/m (low); clay, 18.8% (medium) and CaCO3, 17.1% (high). In the study for the major elements. The major elements of these soils are Si, followed by Ca and Al, with an average content of 203.7 g/kg, 105.5 g/kg and 74.0 g/kg respectively. On the other hand, 27 trace elements have been studied. Of all of them, it can be highlighted the average values of Ba (361.8 mg/kg), Sr (129.3 mg/kg), Rb (83.4 mg/kg), V (74.2 mg/kg) and Ce (70.6 mg/kg). Ba, V and Ce values are higher and the values of Sr and Rb are lower to those found in the literature. The discriminant analysis shows a percentage of grouping of 91%. The content of chemical elements together with the physico-chemical characteristics allows grouping the soils in 4 group according to their order in the classification to Soil Taxonomy; due to the importance of the Calcisols in Castilla-La Mancha, it has been decided to establish them as their own group even if they do not appear in Soil Taxonomy classification.

Effects of graft quality on growth and grapevine-water relations

Climate change is challenging viticulture worldwide compromising its sustainability due to warmer temperatures and the increased frequency of extreme events. Grafting Vitis vinifera L.

Inhibition of Oenococcus oeni during alcoholic fermentation by a selected Lactiplantibacillus plantarum strain

The use of selected cultures of the species Lactiplantibacillus plantarum in Oenology has grown in prominence in recent years. While initial applications of this species centred very much around malolactic fermentation (MLF), there is strong evidence to show that certain strains can be harnessed for their bio-protective effects. Unwanted spontaneous MLF during alcoholic fermentation (AF), driven by rogue Oenococcus oeni, is a winemaking deviation that is very difficult to manage when it occurs. This work set out to determine the efficacy of one particular strain of Lactiplantibacillus plantarum(Viniflora® NoVA™ Protect), against this problem in Cabernet Sauvignon must. The work was carried out at commercial scale and in a winery environment and compared the bio-protective culture with the more traditional approach of reducing must pH by the addition of tartaric acid. The combination of both was also investigated. The concentration of both Oenococcus oeni and Lactiplantibacillus plantarum was determined using qPCR. The adventitious Oenococcus oeni showed the most growth during AF in the control wine, whereas in the wines treated with Lactiplantibacillus plantarum a bacteriostatic effect against this species was observed. This effect was comparable to the wines treated with tartaric acid. This has particular commercial relevance for controlling the flora in musts with high pH, or when the addition of tartaric acid is either not permitted or is prohibitive for other reasons.

Postveraison shoot trimming in Tannat and Merlot: preliminary results on yield components, plant balance and berry composition

There is currently a trend towards the production of wines with low alcohol content. To achieve this, grapes with low sugar content must be used. There are techniques at the vineyard level that can delay ripening and avoid excessive sugar accumulation without, a priori, affecting the final polyphenol content. Postveraison shoot trimming (PVST) is experimentally evaluated for these purposes, but its impact under Uruguayan climatic conditions with high interannual variability is not known. The aim of this work is to assess the PVST in Tannat and Merlot cultivars and their impact on yield components, plant balance and berry primary composition. In this study, two commercial vineyards of 10 years old Tannat and Merlot (grafted on SO4) at Canelones Department were selected. During the 2020-201 growing season, grapevines were submitted to PVST when grapes reached 15º Brix. In a randomized block, trimmed (T) and control (C) plants were evaluated with three repetitions each cultivar. Evaluation of the evolution of primary berry composition during ripening, measurement of yield components and plant balance were performed. For both cultivars, PVST did not affect yield components. Merlot reached 5.4 kg per plant and Tannat 7.1 kg, with not statistical significance between treatments. However, statistical differences were observed in terms of plant balance. In Merlot Ravaz Index reached a difference of 5.3 (12.0 in T and 6.7 in C) meanwhile Tannat reached 3.5 of statistical difference (13.7 in T and 10.2 in C). The tendency to imbalance for the treated plants had an impact on the final grape composition. Merlot grapes showed statistical difference in final total acidity (0.3 g of difference between treatments) while treatments impact final sugar content on Tannat grapes (10.0 g of difference between treatments). Further studies are needed to assess the impact of different canopy management techniques in our conditions.