Soil electrical resistivity measurement: from terroir characterization to within-field crop inputs management

Soil Electrical Resistivity measurement is a zoning tool used by soil scientists and agronomists in viticulture. Indeed, the measure enables to optimize pedological surveys (position and number of soil sampling) to obtain a very precise final soil map. Since 2007, Tutiac Winegrowers (Vignerons de Tutiac, Bordeaux) have decided to map all their vineyards (over 4000 hectares) with this technology. Maps are used by the Winery to provide advices more suited to the terroir: grass cover, fertilization, replanting (grape variety/rootstock), grape selection and to define the potentiality of each plot regarding market expectations. However, because of logistic reasons, the Tutiac Winery is not able to use the very high-resolution of the maps for within-field valorization (selective harvest). But, intra-block information of resistivity maps, crossed with complementary measures, can be used in a different way, in particular to cut down use of phytosanitary treatment. This paper presents the GIPI project which plans to vary the rate of crop inputs inside the field. Agronomic (input data, abacus) and technological aspects (software, direct injection sprayer) will be described through an example of a vineyard (25 hectares) where many measurements (resistivity, pedology, NDVI…) have been carried out.