In soils that are highly acidic or highly alkaline, key minerals and trace elements may not be available in sufficient quantities for plants to grow properly
Extremes in pH levels can also mean high concentrations or more accessible forms of minerals such as aluminium, which can be toxic to plants
pH levels affect the microbial processes that allow organic matter to decompose and deliver nutrients to the soil.
Certain species have a preference for more acidic or more alkaline conditions, depending on their nutritional needs