Soil Weathering and Nutrient Dynamics in Response to Land-Use Change Following Forest Conversion to Tea Plantations

Forests’ conversion to tea plantations is a land use transition type with high economic value in China. How this conversion affects soil weathering and nutrient characteristics remains unclear. Here, we selected six soil profiles (three pairs) from representative tea plantations and adjacent forests in China. We quantified the weathering intensity (chemical index of alteration (CIA), base-to-alumina ratio (ba), and weathering index of Parker (WIP)) by soil geography and elemental geochemistry methods and revealed nutrient distributions along with soil profiles. The results showed that soluble elements (such as K2O, CaO, MgO and Na2O) and SiO2 were noticeably leached, while Al2O3 and P2O5 were enriched. The geochemical indices showed that the soil profiles of tea plantations (CIA: 80.6%, ba: 0.3 and WIP: 34.6%) experienced stronger chemical weathering than those of forest soils (CIA: 76.0%, ba: 0.4 and WIP: 39.7%). The mean sensitivity indexes (SI) of soil pH, soil organic matter (SOM), total phosphorus (TP) and total potassium (TK) were −7.0%, −24.8%, 53.7% and −8.6%, respectively. This reflected that tea plantations would lead to soil acidification, organic matter depletion, phosphorus enrichment, and potassium deficiency. Our work underscores the significant impact of anthropogenic tea-garden cultivation on pedogenesis; future management must emphasize rational fertilization to prevent soil degradation.