The influence of depth on the water retention properties of vineyard soils

Abstract

The relationships between the factors that influence the water retention properties of soils (bulk density, sand, silt, clay, organic matter and CaCO3 contents), and their gravimetric moisture at field capacity (FC), permanent wilting point (PWP), and their available water capacity (AWC), were studied in 104 surface horizons and 95 subsurface horizons of vineyard soils in the Castilla-La Mancha region of Spain. Taking all soil types together, the depth of the horizon was found to influence PWP and AWC, while the factors with the most significant linear relationship with AWC, both for surface and subsurface horizons, were sand content (r = − 0.47 and − 0.63, respectively) and silt content (r = 0.37 and 0.62, respectively). However, when each FAO Reference Soil Group was studied independently, only Calcisols, Luvisols and Regosols showed significant differences between these horizons in terms of AWC. Greater clay contents were associated with greater FC, PWP and AWC only in Luvisol surface horizons (r = 0.44, 0.40 and 0.33, respectively), and with FC and PWP in subsurface horizons (r = 0.64 and 0.64). A greater CaCO3 content was associated with a greater AWC only in Calcisols, both in surface and subsurface horizons (r = 0.49 for both). Finally, the organic matter content and bulk density of the different soil types showed no clear trend with respect to any soil water retention property; a certain positive effect of organic matter on water retention properties was observed only in the surface horizon and not in the subsurface horizon. A map of the spatial distribution of AWC in surface and subsurface horizons is proposed as a soil management instrument.