Our study involved a 4-year pot investigation of loamy sand soil to which waste organic materials, brown coal ash, and mineral fertilizers containing nitrogen, phosphorus, potassium, and magnesium (NPKMg) were applied. Maize was the tested plant material grown in this soil mixture. The aim of this investigation was to determine the levels of enzymatic activities of acid phosphatase (ACP), alkaline phosphatase (ALP), urease (URE), and soil dehydrogenases (SDH) in this soil treated with organic materials, ash, and mineral fertilizers. Organic materials and ash significantly affected enzymatic activity of the soil. Mineral fertilization increased activities of ACP and SDH accompanied by a decrease in ALP activity. Data thus indicate that treatment of soils with organic materials, ash, and fertilizers alters soil enzymatic activity and, subsequently, the potential growth of corn.