Integrated Nutrient Management Enhances the Growth and Yield of Cauliflower ( <i>Brassica oleracea</i> var. <i>botrytis</i> ) in Calcareous Soil: A Field Experiment with Mineral, Organic, and Biofertilizers

Calcareous soil, which covers large areas of Syria and other arid regions, is characterized by high pH, elevated calcium carbonate content, and low availability of essential nutrients, posing significant constraints to vegetable production. Although integrated nutrient management combining mineral, organic, and biofertilizers has shown promise in improving crop performance, field-based evidence from calcareous soil in Syria remains limited. This study aimed to identify the most efficient fertilization strategy for cauliflower (<i>Brassica oleracea</i> L. var. <i>botrytis</i>) in calcareous soil. We hypothesized that a balanced mixture of mineral, organic, and biofertilizers would enhance nutrient availability and crop performance more effectively than single-fertilizer applications. For this, a field experiment was conducted during the 2024-2025 growing season (October-February) at the Shabaa Research Station using a randomized complete block design with 13 fertilization treatments and three replicates. At the end of the experimental period, soil and plant macronutrients and cauliflower growth parameters were measured. Results demonstrated that the treatment combining 50% mineral fertilizer, 25% fermented cow manure, and 25% biofertilizer significantly (<i>p</i> <0.05) enhanced the plant height (51.0 cm), head diameter (31.24 cm), and total yield (43.35 tons ha^-1), representing a 44.5% increase over the unfertilized control and outperforming mineral fertilization alone. Treatments with a high share of mineral fertilizers (75% mineral fertilizer + 25% organic fertilizer) increased the plant nutrient content but were less effective than balanced mixtures, in terms of crop yield. Moreover, individual fertilizer application resulted in a significant reduction in plant growth compared to the use of mixtures. This study highlights the agronomic and environmental benefits of integrated fertilization strategies in nutrient-deficient calcareous soil, including improved nutrient use efficiency, reduced chemical fertilizer input, and enhanced soil properties.