Optimizing Cucumber (Cucumis sativus L.) Growth and Yield in Calcareous Soil through an Integrated Application of Poultry Manure, Phosphorus, and a Zinc Foliar Spray under Greenhouse Conditions

Cucumber farmers often face significant challenges when cultivating crops in calcareous soils, where the availability of essential nutrients such as phosphorus and zinc is limited, particularly under protected greenhouse conditions. These constraints are mainly attributed to high calcium carbonate content and alkaline soil reactions, which reduce nutrient solubility and plant uptake. Therefore, this study was conducted to evaluate the effects of poultry manure, phosphorus fertilizer, and foliar zinc application on plant growth, yield, and nutrient use efficiency. The experiment was arranged in a split–split plot design with three replicates to ensure statistical reliability, including different levels of each input to identify the most effective combination for improving crop performance.The results clearly demonstrated that the combined application of organic and mineral fertilizers significantly enhanced plant growth and yield compared with individual treatments. The interaction between poultry manure and phosphorus fertilizer played a crucial role in improving phosphorus availability and uptake, which was reflected in higher productivity and better plant performance. Total yield increased from approximately 552.9 t ha⁻¹ in the untreated control to about 665.2 t ha⁻¹ under integrated fertilization, representing a substantial improvement. The highest yield, reaching 678.6 t ha⁻¹, was recorded when poultry manure, phosphorus, and zinc were applied together at optimal levels. Foliar application of zinc further enhanced crop performance, although its effect was mainly supportive rather than strongly interactive.The improvement in yield was associated with enhanced soil properties, reduced phosphorus fixation, and improved nutrient availability and uptake efficiency. These findings indicate that integrating organic amendments with mineral fertilizers is an effective and practical strategy to improve cucumber productivity and nutrient use efficiency in calcareous greenhouse soils.