茶园—土壤系统铝和氟的生物地球化学循环及其对土壤酸化的影响

BIOGEOCHEMICAL CYCLE OF ALUMINIUM AND FLUORINE IN TEA GARDEN SOIL SYSTEM AND ITS RELATIONSHIP TO SOIL ACIDIFICATION

黄棕壤植茶以后,土壤pH下降,土壤酸度随植茶年限的增长而增大,且上层土壤pH的减幅大于下层土壤。茶园土壤的酸化是与茶树对铝和氟的生物积聚、土壤交换性铝与铝络合物的增加以及土壤盐基的淋溶有关。茶树落叶中铝和氟的含量分别高达5836—6136 ppm和469—520ppm;茶树透冠水和土壤渗漏液中均有相当多的Al和F,茶园土壤系统中铝和氟的循环,不仅导致土壤Al^(3+)及F^-的增多,还使表土的有机络合态铝以及土壤交换性复合体和土壤溶液中的氟铝络合物积聚。因此,土壤中铝和氟的积累、转化及其生物地球化学循环是茶园土壤酸化的主要原因。

This article deals with the influence of tea plantation on the acidification of yellow-brown earth. The soil pH decreased after planting tea, and the soil tended to be further acidified with the time of growing tea. The decrement of soil pH was higher in upper layers. than in lower layers. The acidification of soil in tea garaen was related to the biological accumulation of aluminium and fluorine by tea trees, to the increade of soil exchangeable aluminium and aluminium complexes, and to the eluviation of basic cations in soils. The contents of aluminium and fluorine in the fallen leaves of tea were 5836—6136 ppm and 469—520 ppm respectivly, and the aluminium content in the percolating solution of soil in tea garden decreaed from 0.46—0.55 mg L^(-1) in the litter floor to 0.01—0.15 mg L^(-1) in the 50 cm deep soil. Aluminium and fluorine cycle in tea garden resulted in not only the increase of A^(3+) and F in soil bur also the accumulation of organic complex aluminium in surface soil and aluminium-fluorine complexes in soil exchangeable complexes and soil solution. Therefore, the accumulation of aluminium and fluorine in soils and its biogeochemiCal cycle were the main reason for the acidification of soils in tea gardens.