Research on acidification and changes in mineral element concentrations in ferralsols from long-term tea plantations in Guizhou Province, China

Aims This study aimed to investigate where acidification occurred in soil profiles of Guizhou tea gardens, and the influence of acidification on the availability of soil mineral elements in order to inform soil nutrient management and improvement practices in tea gardens. Methods The acidification characteristics were investigated in soils from plantations grown for various numbers of years and across different soil layer profiles. Moreover, the pH buffering capacities (pHBC) of soils were evaluated and changes of mineral elements’ contents due to soil acidification were explored. Key results With increased tea plantation age, the acidification rate of 0–20-cm soil layers reached 0.025 pH unit/year. Soil acidification extended from the surface layer downwards through profiles, while the pH of entire soil layers were <4.5 after 40 years of tea plantation. The pHBC of soils were <30 mmol/kg, remaining at a weak sensitive level. Fe, Mn, Cu, Zn, Mo, and B concentrations exhibited decreasing trends in soils, while As, Pb, Cr, and Cd exhibited enrichment at the surface. Tea plantation age and soil depth were significantly correlated with the available concentrations of soil mineral elements. Conclusions Soil acidification gradually increased downward from the surface and soil minerals were lost in acidic environments, while the acid buffering capacity was reduced. Implications These results suggest that organic fertilisers and trace elements should be supplemented as needed in the management of tea gardens to achieve long-term stability of quality and yields.