How does granite’s mineral composition affect soil pH?

Granite, an igneous rock composed primarily of quartz, feldspar, and mica, plays a significant role in determining soil pH through natural weathering processes. The mineral composition of granite, particularly its feldspar content, directly affects soil acidity over time.

When granite weathers, feldspar minerals break down into clay and release alkaline elements like potassium, calcium, and sodium. These elements neutralize acidic compounds in the soil, gradually raising the pH level. However, the rate of this process depends on environmental factors such as rainfall and temperature.

Quartz, another major component of granite, is chemically inert and does not contribute to pH changes. Meanwhile, biotite mica can release small amounts of iron and magnesium, which may slightly acidify the soil.

In regions with high granite content, soils tend to be more neutral or slightly alkaline due to the buffering effect of feldspar-derived minerals. This mineral-driven pH adjustment influences nutrient availability, microbial activity, and plant growth in granite-rich ecosystems.

Understanding this relationship helps in agricultural planning and ecosystem management, especially in areas where granite bedrock is prevalent. Farmers and gardeners can use this knowledge to predict soil behavior and select appropriate amendments for optimal plant health.