Effective management of produced water (PW), a by-product of oil extraction in Oman, is crucial for sustainable water use and environmental protection. PW contains petroleum residues, heavy met-als, and salts, requiring treatment before reuse. In the Nimr oil field, PW is partially treated through constructed wetlands with reed grass. This study evaluates the feasibility of reusing treated PW for irrigation by assessing its effects on soil quality and mineral accumulation in plants under different irrigation conditions. Field experiments were at Sultan Qaboos University (SQU) and Nimr wet-lands treated PW (TDS ~6,500–7,000 mg/L) along with lower-salinity water sources. Soil amend-ments (biochar and gypsum) were tested for salinity mitigation. Results showed that PW irrigation significantly increased boron and major cations (Na, K, Ca, Mg) in soil and plant tissues, leading to higher soil salinity and potential decline in soil health. While biochar reduced boron levels, neither amendment improved plant growth or nutrient uptake. Plants irrigated with PW exhibited signs of salinity stress, including reduced leaf development and premature senescence. These findings highlight both the potential and challenges of PW reuse for irrigation. Adaptive irrigation strategies and soil management practices are essential to maximize benefits while mitigating long-term soil salinity risks.

Greenhouse vegetable production is expanding in arid regions, but information on microbial responses to contrasting management systems remains limited. This study investigated chemical properties, microbial abundance, activity, taxonomic diversity, and function potential based on 16S rRNA gene and ITS sequencing of soil samples collected from organically and conventionally managed cucumber, tomato, and eggplant crops in irrigated greenhouses in Oman. Organic management increased mean soil organic matter from 3.9% to 7.3%, representing an 87% increase, and bacterial abundance from 20.2 to 95.7 × 10⁴ CFU g⁻¹, representing a 4.7-fold increase compared with conventional management (p < 0.05). Organic management increased pooled bacterial functional diversity, including the Shannon index from 2.73 to 2.96 and the Simpson index from 0.89 to 0.92, whereas the fungal Shannon diversity index decreased from 2.90 to 2.34 and evenness from 0.40 to 0.29 (p < 0.05). Taxonomy-based functional inference indicated shifts in carbon- and nitrogen-cycling potential and reduced representation of methanogenesis-associated functions under organic management. PERMANOVA showed that crop type explained the largest proportion of multivariate variation (R² = 0.350), followed by the management × crop interaction (R² = 0.236) and management system (R² = 0.134; all p = 0.001). These results indicate that crop species is a major driver of soil microbial characteristics in arid-climate greenhouses, while organic management modified microbial abundance, diversity, and function in a crop-dependent manner.