A field experiment was conducted in a loam soil at the research station of the College of Agricultural Engineering Sciences / University of Baghdad, during the autumn season 2023 to find out the effect of adding molasses residual, silicate- solubilizing bacteria, mineral fertilizers and their interactions on the availability of N, P, K, Si and organic matter in the soil after harvesting the cauliflower crop. The experiment was conducted in a factorial randomized complete block design (RCBD) with three replicates. The first factor included three levels; no addition mineral fertilizer M₀ and adding 50% of the fertilizer recommendation (150 kg N ha^-1, 65.5 kg P ha^-1 and 124.5 kg K ha^-1) M₁ and adding 10 liters ha^-1 of potassium silicate fertilizer M₂ with adding 100% of the fertilizer recommendation for comparison. The second factor included adding biological and organic fertilizers at three levels the first level; no addition B₀ and The second level included adding silicate- solubilizing bacteria (Bacillus mucilaginosus) B₁. The third level included adding date waste at a level of (10 Mg ha^-1) B₂. The results showed the significant effect of adding molasses factory waste, silicate- solubilizing bacteria and mineral fertilizer to the soil. The interaction treatment M₁ B₂ achieved the highest values ​​in the availability of N, P and organic matter