Hainan Island is located in the northern periphery of the tropical world.The environment is suitable for a number of tropical economic crops.The content of soil organic matter under rubber plantation is around 10- 20 g kg-1.Cu,Zn,Mn,As,Mg,Ca and K in the soil profile reflect the parent material and the intensive weathering and leaching in the area.Copper has noticeably accumulated in the lower horizon,whereas the concentrations of Ca,Mg and K.in rubber trees are 0.5- 4.9,2.2- 4.3 and 4.6-10.2 g kg-1 respectively.These three elements are mostly distributed in the plant roots and are particularly required during the development of new leaves early in the season.
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