The tendency to use natural organic wastes is one of the environmentally safe applications in crop production. Therefore, the presented study aimed to determine the effect of adding mushroom and sulfur residues to gypsiferous soil and their efficiency in improving the production of broccoli ‘Balimo F1’ (Brassica oleracea var. ‘Italica’). The study set out in a randomized complete block design with three replications. The 10 combined treatments of the spent mushroom substrate (SMS) and sulfur residues consisted of 0% and 15% (SMS), and 0, 1000, 2000, 3000, and 4000 S kg ha^-1. The interaction of the spent mushroom substrate with sulfur showed significant differences for most growth and yield-related traits of broccoli, including leaf length, leaves per plant, roots per plant, head diameter, head weight, total yield, and harvest index, as compared with the control treatments. Among all the treatments in broccoli, the highest total yield (148,702 kg ha^-1) resulted in the treatment SMS – 15% + Sulfur – 3000 kg ha^-1, followed by the total yields of 111,608 and 105,663 kg ha^-1 produced by the treatments SMS – 15% + Sulfur – 4000 kg ha^-1 and SMS – 15% + Sulfur – 2000 kg ha^-1, respectively. However, the minimum total yield in broccoli (28,295 kg ha^-1) came from the treatment SMS – 0% + Sulfur – 3000 kg ha^-1, followed by a total yield of 33,793 kg ha^-1 obtained in the treatment SMS – 0% + Sulfur – 4000 kg ha^-1. Overall, and compared with the control, a significant influence occurred due to the interaction of spent mushroom substrate and sulfur with levels of 15% and 3000 kg ha^-1, respectively.

Keywords: Broccoli, spent mushroom substrate (SMS), composting, sulfur, inorganic fertilizer, organic manure, gypsiferous soil

Key findings: For growth and yield-related traits of broccoli, a significant influence occurred due to the interaction of spent mushroom substrate (SMS) and sulfur at the levels of 15% and 3000 kg ha^-1, respectively.