Chemical Speciation and Availabilith of Mn and Zn to Tea in Soils of the Fenghuangshan Tea Belt,East Guangdong
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Abstract
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 then could be sorted into five fractions,which followed the order of residue>Fe/Mn-oxide-bound>organic-matter-bound>exchangeable>carbonate-bouned.The contents of Fe/Mn-oxide-bound and carbonate-bound Mn and nitrate-bound,organ-ic-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 911.7-1219.4 mg·kg-1,and 1046.3 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.
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