Factors Affecting Bioavailability of Chromium, Zinc and Nickel in Soil at Wuyi Rock Tea Plantations

  Objective  Bioavailability of chromium (Cr), zinc (Zn) and nickel (Ni) as well as factors affecting it in plantation soil were studied as they closely relate to the growth of tea plants.

  Method  Contents and forms of Cr, Zn and Ni in the soil and the leaves on plants at rock tea plantations in Mt. Wuyi, Fujian were determined. Factors affecting the bioavailability of these elements were analyzed.

  Result  Majority of the elements in the sampled soils was residues from the native land, rather than accumulated from external sources. Both bioavailability and enrichment coefficients of Zn were the greatest followed by Ni, then Cr. The bioavailability of Ni inversely correlated to the pH and organic matters of the soil, and the enrichment coefficient of Zn to the pH only. Whereas, the Ni enrichment coefficient correlated inversely to the organic matters, altitude of plantation or age of plant.

  Conclusion  Cr, Zn and Ni in the soil basically existed from the origin of the land. Their bioavailability directly governed the mineral absorption of the tea plants and could be affected to varying degrees by the pH and organic matters in soil, the elevation of plantation, and/or the age of tea bushes.