Soil Salinity Survey of Central Coast Vineyards
The objective of this project was to evaluate the current soil salinity status of established vineyards in the area east of Paso Robles in San Luis Obispo County. Surface soil samples from within the vine row were taken at 100 locations. The results indicate that the soil electrical conductivity, the principle component of interest, is on average 2.2 dS/m, approaching the threshold value of 2.5 above which appreciable growth and yield reductions may occur. Twenty-nine percent of the sites had electrical conductivity values between 2.5 and 4.1, and six percent above 4.1, over which severe effects on growth and yield can be expected. That these values were measured after two relatively wet winters suggests that during drier cycles, many soils may have, or will have, significantly higher soil EC levels. Re-sampling of the same locations is planned to take place every three years to evaluate any long term trends in soil salinity.