Effect of soil acidification induced by a tea plantation on chemical and mineralogical properties of Alfisols in eastern China

摘要

The effect of a tea plantation on soil basic properties, chemical and mineralogical compositions, and magnetic properties of Alfisols from eastern China was studied. Under the tea plantation, acidification took place within a soil depth of 70 cm, with the maximum difference in pH in the upper 17 cm (△pH = 2.80). Both the tea plantation and unused soil profiles were predominated by free Fe and Al oxides, i.e. citrate/bicarbonate/dithionite extractable Fe (Fe_d) and Al (Al_d). Tea plantation soil was characterized by higher Al_d and Fe_d and lower Fe oxalate, Fe_2O_3 and Al_2O_3; CaO was depleted, whereas SiO_2 accumulated. Acidification induced by the tea plantation led to destruction of vermiculite followed by dissolution of the hydroxy-Al interlayers within its structure. The data clearly demonstrated that significant soil weathering occurred with acidification caused by tea cultivation. This acidification also resulted in decreased content of ferrimagnetic minerals due to the dissolution of minerals and movement of Fe in the profile.