Spatial variability in Ontario Cabernet Franc vineyards: I. Interrelationships among soil composition, soil texture, soil and vine water status

Spatial variability of vine water status and its relationship to soil moisture (SM) and physical properties was studied in ten vineyard blocks of Vitis vinifera L. Cabernet Franc in the Niagara Peninsula, Ontario, using geomatic techniques. Soil texture, soil chemical composition, SM, and leaf water potential (ψ; vine water status), were determined on ≈ 80 sentinel vines per vineyard. Water status zones were identifi ed in vineyard-specifi c GIS-generated maps using leaf ψ and SM measurements. SM was temporally consistent for nine of ten sites (2005-2006), all sites (2006-2007), and eight sites (2005-2007). Vine water status was temporally consistent for two sites (2005-2006) and three sites (2006-2007), but leaf ψ zones were transient at some sites with temporally variable spatial distribution (except one site with consistent water status zones 2005-2007). SM and leaf ψ consistently were directly-correlated spatially with % clay, % organic matter (OM), cation exchange capacity (CEC), soil pH, base saturation (BS), soil K/Ca/Mg. Low SM and water status zones were related to low % clay, OM, CEC, soil pH, BS, soil K/Ca/Mg zones. This indicates that precision viticulture may be applied to soil texture, SM, or leaf ψ-based vineyard sub-zones that could relate to differing quality levels. Key words: Global positioning systems, geographic information systems, soil moisture, leaf water potentia