粤东凤凰山茶区土壤锰、锌赋存形态特征及对茶叶的有效性

Chemical Speciation and Availability of Mn and Zn to Tea in Soils of the Fenghuangshan Tea Belt,East Guangdong

采用连续化学提取法对粤东凤凰山茶区12个茶园土壤Mn和Zn的5种赋存形态特征及对茶叶的有效性进行了研究。结果发现,茶区土壤Mn平均含量为337 mg.kg-1,Zn平均含量为166.0 mg.kg-1,Mn和Zn的形态分布规律均表现为残渣态>铁锰氧化物结合态>有机束缚态>可交换态>碳酸盐结合态。土壤铁锰氧化物结合态和碳酸盐结合态Mn含量以及碳酸盐结合态、有机束缚态和铁锰氧化物结合态Zn含量分别与土壤pH值呈显著正相关,可交换态Mn含量与土壤pH值呈显著负相关;有机束缚态Mn、Zn含量以及铁锰氧化物结合态Zn含量分别与土壤有机质含量呈显著正相关,而铁锰氧化物结合态Mn含量与土壤有机质含量呈显著负相关。茶区茶叶Mn平均含量为1 046.3 mg.kg-1,Zn平均含量为42.0 mg.kg-1。茶叶Zn含量分别与土壤可交换态、有机束缚态、碳酸盐结合态Zn含量以及有机质含量呈显著正相关;茶叶Mn含量分别与土壤可交换态、碳酸盐结合态、有机束缚态Mn含量呈显著正相关,而与土壤pH值呈显著负相关。土壤pH值和有机质含量对茶区土壤Mn和Zn的化学形态分布及茶叶中Mn和Zn的累积有重要影响。

Soil samples were collected from 12 tea gardens in the Fenghuangshan Tea Belt,East Guangdong for analysis of forms of Mn and Zn existing in the soil and their availability to tea,using a sequential chemical extraction procedure.It was found that in the soil,the mean Mn content was 337 mg·kg-1 and the mean Zn content 166.0 mg·kg-1.Both of them could be sorted into five fractions,which followed the order of residueFe/Mn-oxide-boundorganic-matter-boundexchangeablecarbonate-bound.The contents of Fe/Mn-oxide-bound and carbonate-bound Mn and nitrate-bound,organic-matter-bound and Fe/Mn-oxide-bound Zn in the soil were all positively related to soil pH,while that of exchangeable Mn was negatively related;the content of organic-matter-bound Mn and Zn and Fe/Mn-oxide-bound Zn were all positively related to that of soil organic matter,while that of Fe/Mn-oxide-bound Mn was negatively related.The Mn content in tea leaves was in the range between 911.7-1 219.4 mg·kg-1,and 1 046.3 mg·kg-1 on average and also positively related to that of exchangeable,carbonate-bound and organic-matter-bound Mn,separately,but negatively related to soil pH.The Zn content in tea leaves was in the range between 34.3-59.5 mg·kg-1,and 42.0 mg·kg-1 on average and also positively related to that of exchangeable,organic-matter-bound and carbonate-bound Zn and soil organic matter content,separately.In conclusion,soil pH and organic matter content are the two important factors affecting on chemical speciations of Mn and Zn in the soil of the tea belt and their accumulation in tea leaves.