Bio-Based Amendments Influence Yield and Quality of Basil (Ocimum basilicum L.) Grown in Moderately Saline Soil

Cultivation on saline soils is becoming increasingly necessary to meet the growing global demand for food, particularly in the Mediterranean basin, where an estimated 25–35% of agricultural soils are affected by salinity-related constraints. Addressing this growing challenge requires more than the use of desalinated or purified irrigation water, which is often expensive, only partially effective, and limited by the increasing scarcity of freshwater resources. Therefore, the development of sustainable strategies to mitigate the adverse effects of soil salinity on crop production is urgently needed. The aim of this study was to evaluate the effectiveness of several bio-based amendments, applied individually or in combination, on basil (Ocimum basilicum L.) cultivated under saline soil conditions (EC1:2.5: 2.0 dS m−1). The tested amendments included gypsum for defecation from sludge (GDS), wood ash, Ecklonia maxima seaweed extract, and combinations of GDS with either wood ash or seaweed extract. For a crop cycle, a pot experiment was conducted using a completely randomized design, with three replicates of 10 pots each. Among the tested amendments, GDS, either alone or combined with wood ash, was associated with being the most effective in enhancing basil performance under saline conditions. These findings highlight the potential of bio-based amendments as sustainable tools for improving basil crop productivity in salt-affected soils.