Use of geomatic technologies to determine the basis for Terroir. Spatial variation in five Ontario Chardonnay vineyards

Abstract: The aim of this study was to test the hypothesis that soil texture would play a minor role in the determination of yield components, fruit composition, and wine sensory attributes of Chardonnay (i.e. the terroir effect), and that vine size, crop size and associated fruit environment would play the major roles. Five Chardonnay vineyards in the Niagara Peninsula of Ontario, Canada were chosen for study. These vineyards were located on sites with heterogeneous soil types to allow study of the impact upon yield, fruit composition and wine sensory attributes of: 1. Soil texture with mesoclimate kept constant; 2. The comparative magnitude of effects of soil texture and vine vigor. Vineyard blocks were delineated using global positioning systems (GPS), and a series of 72 to 162 data vines per site were geo-located within a sampling grid imposed on each vineyard block. Data were collected on soil texture, soil composition, tissue elemental composition, vine performance (yield components and weight of cane prunings), and fruit composition. These variables were mapped using geographical information systems (GIS) software and relationships between them were elucidated. Soil texture and composition were occasionally correlated to yield components and fruit composition but often these relationships were site-specific. Spatial relationships were common between % sand and clay, vine size, yield, berry weight, soluble solids (Brix), and titratable acidity (TA); however, relationships were both vineyard and vintage dependent. Several spatial relationships were apparent as well between vine size, yield, Brix, TA, and various soil/petiole composition variables, including organic matter, soil pH, cation exchange capacity, and soil/petiole N, P, K, Ca, Mg, and B. Spatial relationships between yield, berry weight, berry composition, vine size, and several soil physical variables suggest a likely soil basis to the so-called 'terroir effect'. Vine size, yield, and berry weight were stable temporally within individual vineyards despite differences in annual climatic conditions. Soil texture (% sand) was frequently associated with high vine size, yield, and berry weight. Vine size directly correlated with berry weight. TA was often correlated with vine size. Soil composition had little relationship to petiole composition, fruit composition or yield except in a few specific cases, e.g., between pH and soil K.