Abstract:

To investigate the chemical form distribution characteristics of available manganese (Mn) and zinc (Zn) in typical white tea plantation, 8 soil profile samples (0-100 cm), 32 soil surface samples (0-20 cm) and 32 tea leaves samples were collected in Fuding city, Fujian province. The concentrations of different chemical forms of Mn and Zn were measured by Flame Atom Absorbability Spectrometer. The results showed that, the average concentrations of total Mn and Zn in soil were 394.84 mg∙kg^-1 and 101.58 mg∙kg^-1, respectively, which were higher than their background concentrations in Fujian province. The available Mn and Zn concentrations in soil were 49.41 mg∙kg^-1 and 3.34 mg∙kg^-1, and 28.13% samples were deficient in available Mn. The available Mn concentrations of 34.38% soil samples were lower than the indices of high yield tea plantation. The concentrations of different chemical forms of Mn were generally declined as following order: residuals > iron and manganese oxides > organic-bound > exchangeable > carbonate-bound, while the concentrations of different chemical form of Zn were generally declined as following order: residuals > exchangeable > iron and manganese oxides > carbonate-bound > organic-bound. For the profile distribution, the contents of different forms of Mn increased with the depth increasing. The contents of the exchangeable and organic-bound Zn reduced with the depth increasing, whereas, the other forms of Zn were not evident distribution regulation in soil profiles. Soil pH, organic matter and total nitrogen contents were the key factors of different chemical forms of Mn and Zn. There were significant positive relationships between the exchangeable and carbonate-bound Mn contents and available potassium content in soil. However, carbonate-bound Mn content decreased with available potassium content increasing in soil. There was a positive relationship between the content of exchangeable Zn and soil cation exchange capacity. But the correlations between available phosphate and all chemical forms of Mn and Zn in soil were not significant. The average concentrations of Mn and Zn in tea leaves were 664.46 mg∙kg^-1 and 45.03 mg∙kg^-1, respectively. There were positive relationships between Mn content in tea leaves and the contents of total, exchangeable, iron and manganese oxides, and organic-bound Mn in soil. The caffeine content also positively related to the above four chemical forms of Mn. There was a positive relationship between Zn content in tea leaves and total Zn in soil. The TP/AA ratio in tea leaves were negatively related to organic-bound Zn in soil. In general, the soils in some tea plantation in Fuding city were deficient in Mn and Zn, while the caffeine content in tea leaves was related to soil Mn forms. Therefore, to improve tea quality, Mn and Zn fertilizer and intercropping green manure crops should be used in the tested tea plantations.

Key words: white tea, tea plantation, soil, manganese, zinc, form, profile distribution, availability

摘要：

为探讨福建白茶产区茶园土壤锰锌形态特征及对茶叶的有效性,在典型白茶产地—福鼎市采集8个剖面（0—100 cm）土壤样品、32个耕作层（0—20 cm）及相应鲜叶（一芽二叶）,分析土壤中锰锌含量、赋存形态、剖面分布规律及影响因素。结果表明：福鼎市茶园耕作层土壤全锰和全锌含量均值分别为394.84 mg∙kg^-1和101.58 mg∙kg^-1,高于福建省土壤背景值;土壤有效锰锌含量均值分别为49.41 mg∙kg^-1和3.34 mg∙kg^-1,28.13%比例的茶园土壤缺锰,34.38%的茶园低于高产茶园标准。茶园土壤锰形态分布规律表现为残渣态>铁锰氧化物结合态>有机结合态>离子交换态>碳酸盐结合态,土壤锌形态分布规律表现为残渣态>离子交换态>铁锰氧化物结合态>碳酸盐结合态>有机结合态。茶园土壤各形态锰含量剖面分布总体表现为由上至下递增趋势,离子交换态锌和有机结合态锌由上至下总体呈现出微弱的递减趋势,其他形态在剖面中分布规律不明显。茶园土壤锰锌形态总体受土壤pH、有机质和全氮的影响,离子交换态锰和碳酸盐结合态锰与土壤速效钾呈显著或极显著正相关,碳酸盐结合态锌与速效钾呈显著负相关,离子交换态锌与土壤阳离子交换量呈极显著正相关,土壤锰锌各形态与土壤速效磷之间相关性均不显著。茶叶锰平均含量为664.46 mg∙kg^-1,锌平均含量为45.03 mg∙kg^-1。茶叶中锰含量与土壤全锰、离子交换态锰和铁锰氧化物结合态锰之间呈显著正相关,茶叶咖啡碱含量也与这4种形态锰含量呈显著正相关。茶叶中锌含量与土壤全锌含量之间呈显著正相关,茶鲜叶酚氨比与土壤有机结合态锌之间呈显著负相关。总体而言,福鼎市部分茶园土壤缺锰现象,茶叶中咖啡碱含量与土壤锰形态之间关系密切,该区茶叶生产需根据茶园地形、管理措施和土壤养分等条件合理施肥,建议部分茶园增施锰(锌)肥和间作绿肥以提高茶叶品质。

关键词: 白茶, 茶园, 土壤, 锰, 锌, 形态, 剖面分布, 有效性