sodium, element that is not a required nutrient for vine growth. Sodium chloride (common salt) is, however, a major hazard for vine-growers, particularly in hot, irrigated areas where ground waters are saline, or where salty irrigation water is applied to the leaves. Sodium has an unfavourable effect on soil fertility because it reduces water infiltration due to its tendency to disperse clay particles. This can be overcome by addition of calcium to the soil, normally as gypsum. See also salinity.
