The study looked at how different types of land use affect soil acidity in black soil. Long-term farming made the soil more acidic, but the type of plants grown had different effects. Maize, soybean, and wheat affected soil pH in that order. Water content also played a role, with higher water levels increasing soil pH. Fertilizer type mattered too - no fertilizer kept pH stable, chemical fertilizer made soil more acidic, while organic fertilizer reduced acidity. This shows that soil pH can be kept stable with different land uses, allowing for sustainable farming.