Effect of Two Calcium Levels and a Chicken Manure-Based Soil Amendment on Tomato Hybrid Performance

Calcium (Ca) is essential for tomato (<i>Solanum lycopersicum</i> L.) fruit quality and for preventing physiological disorders such as blossom-end rot. However, high total soil Ca does not necessarily translate into plant-available Ca due to factors such as soil pH and limited mobility. This study evaluated soil Ca availability and the effect of a chicken manure-based soil amendment on the growth and yield of four tomato genotypes (Pony Express F1, Palomo F1, Toro F1, and Perseo F1) grown on a loam–clay–sand soil containing 4886 ppm Ca. In the first cycle, conducted in a shade house, two Ca application levels (0% and 25% of the crop’s requirement) were tested. The 0% treatment outperformed the 25% treatment regarding yield-related traits, indicating that native soil Ca met crop demand; application of 25% Ca reduced total fruit weight and fruit number by 19.7% and 5.9%, respectively, while the 0% treatment produced 40.8% more first-quality fruits. Perseo F1 (Perseo) produced the highest yield of first-quality fruits (20.61 t ha⁻¹), exceeding Pony Express F1 (Pony express), Palomo F1 (Palomo), and Toro F1 (Toro) by 10.8%, 6.6%, and 51.4%, respectively. In a second cycle under open-field conditions, incorporation of the chicken manure amendment significantly enhanced growth and yield: treated plants reached a 0.85 m height 58 days after transplanting, and overall yield increased to 70.08 t ha⁻¹ compared with 50.30 t ha⁻¹ in the control (21.9% increase). These results indicate that, while native soil Ca can satisfy crop requirements under the studied conditions, soil amendment under field conditions substantially improves plant performance and commercial yield potential.