Abstract
Cabbage (
Brassica oleracea
L.) production in arid regions is limited by low soil fertility, poor organic matter content, and declining sustainability associated with overreliance on inorganic fertilizers. Residue management, particularly of high carbon (C):nitrogen (N) wheat straw, is further complicated by slow decomposition under dry conditions. This study evaluated a sustainable soil amendment strategy that integrates cow dung and wheat straw decomposed using
Bacillus amyloliquefaciens
to improve cabbage growth and productivity in arid Saudi soils. A split–split–plot experiment was conducted over two seasons; three levels each of cow dung (0, 10, 20 t·ha
−1
), wheat straw [0, 20, 30 t·ha
−1
plus nitrogen–phosphorus–potassium (NPK) control], and
Bacillus amyloliquefaciens
(0, 2, 4 L/plot) were tested. Agronomic parameters including head weight, total yield, harvest index, morphological traits, and dry biomass were assessed. Results showed that the combination of 20 t·ha
−1
cow dung, 30 t·ha
−1
wheat straw, and 4 L/plot inoculum produced the highest head weights (up to 2940 g), yields (up to 89.11 t·ha
−1
), and harvest indices (up to 49.49%). Morphological traits such as head diameter, height, and circumference were significantly improved. These treatments outperformed the control in yield and biomass parameters, demonstrating synergistic effects among organic inputs and microbial decomposition, especially under high ambient temperatures. This study concludes that integrating cow dung with
B. amyloliquefaciens
-decomposed wheat straw can significantly improve cabbage yield and growth in arid soils, providing an effective, climate-adapted alternative to synthetic fertilization.