Evaluation of Soil Salinity Conditions in Central Coast Vineyards

This project evaluated the distribution of soil salinity parameters at mature commercial vineyards representative of the Central Coast. Soil cores were taken at one-foot increments to a depth of eight feet, at locations in the vine row, the wheel track area, and the row middle. The resulting data was presented as cross-sectional contour diagrams which show clearly how soil chemistry has been altered over time at the test vineyards. Of particular interest to growers is the fate of salts in the deeper rootzone, and the success of their salinity management programs to maintain the rootzone in good condition. The results demonstrate the extreme variability that occurs with the distribution of salinity conditions in a given soil, due to the soil physical characteristics, the quality of the irrigation water, and the use of management tools such as leaching and amendments. At the most salt-affected site, the changes in soil chemistry and accumulation of salts in the rootzone are very visible with this analysis, and do much to explain the vineyard symptoms at this site. Other test sites which represented more moderate salinity levels had varying patterns of salinity distribution, influenced to some predictable degree by the general drainage characteristics of the soil and the use of additional sprinkler irrigation. The results of this study should serve to encourage growers in the region to occasionally conduct deep soil sampling to inform themselves as to the condition of this important but often overlooked soil fraction.