南方茶园土壤酸化特征及交换性酸在水稳性团聚体中的分布

Acidification of Tea Plantation Soil and Distribution of Exchangeable Acidity in Water-stable Aggregate

通过采集浙江省杭州西湖龙井茶园土壤,研究茶园土壤剖面的酸度特征、养分变化以及交换性酸在水稳性团聚体中的分布特征,以了解南方茶园土壤的酸化过程。结果表明:茶园表层土壤(0-20cm)酸化严重,最低的pHH2O值达到4.0,并且有明显的深层化趋势;表土的有机质和速效磷含量较高,速效磷含量最高可达138.2mg/kg;表土团聚体分级表明茶园土壤有良好的团聚体结构,具有良好的水稳性;除了交换性H+在0.5～0.25mm和0.25～0.106mm水稳性团聚体之间没有明显差别外,交换性酸总量、交换性H+和交换性Al 3+含量均随着水稳性团聚体粒径的减小而降低;水稳性大团聚体中交换性Al 3+相对交换性H+占有明显的优势,而在0.106～0.05mm水稳性微团聚体中交换性H+占有明显的优势。交换性酸总量、交换性H+和交换性铝主要分布于>2mm和2～0.5mm水稳性团聚体中,同时在不同粒级团聚体中的分布随粒径的减小而降低。

In this study,soils were collected from famous Longjing tea garden of Hangzhou,Zhejiang province to clarify tea plantation soil acidification and fertility by analyzing acidity features,nutrients changes,stability of soil aggregates and the exchangeable acidity distribution in water-stable aggregates.The significant topsoil（0-20 cm） acidification was found in tea plantation soils.The lowest pHH2O in the tea plantation soils was as low as 4.0.The tea plantation topsoils were characterized by higher soil organic matter and available phosphorus content.The highest available phosphorus was as high as 138.2 mg/kg.Dry and wet-sieving analysis of aggregates indicated that tea plantation soils had good aggregates structure and higher water-stability.The distribution of acidity in different size aggregates demonstrated that the contents of exchangeable acidity,exchangeable Al3＋ and exchangeable H＋ were decreased as the size of water-stable aggregate was decreased;however,exchangeable H＋ had no distinct difference between 0.5～0.25 mm and 0.25～0.106 mm water-stable aggregates.In 0.25 mm water-stable aggregate,exchangeable Al3＋ was higher than exchangeable H＋,but exchangeable H＋ was higher in 0.106～0.05 mm water-stable aggregate.The percentage of exchangeable acidity,exchangeable Al3＋ and exchangeable H＋ in different water-stable aggregates showed that they were mainly existed in 2 mm and 2～0.5 mm water-stable aggregate,and were decreased as the size of water-stable aggregates were decreased.