Organic carbon sequestration at different age of tea [Camelia sinensis] plantation under the wet tropical area

Abstract

Soil organic carbon [OC] sequestration is affected by some factors, one of which is the vegetation living on it. Tea is a crop on which the part being harvested is the leaves, which are supposed to contribute to soil OC. The objective of the research was to determine the amount of OC sequestered at different crop age under tea plantation in wet tropical areas. The soil samples were taken from 3 different crop ages [36, 21, and 9 years old] under the same slope [>45%] and soil [volcanic] at ≥ 1,400 m asl. As a comparison, the soil was also sampled from the secondary forest around the research site. At each crop age and the forest, the soil was sampled for 100 cm depth with a 20 cm increment. Undisturbed soil samples were taken for soil BD and disturbed soil samples for OC. The result showed that SOC content decreased by soil depth, and the soil BD was not significantly different among the depths. Therefore, the amount of OC sequestered declined by decreasing soil depth. The SOC sequestration rate decreased by increasing the age of tea crop from 1.67 to 0.49 Mg/Ha/y/1-m depth respectively between 9-21 and 21-36 years old. Compared to the secondary forest, however, the OC sequestration under tea plantation improved by 1.50, 1.71, and 1.79 times as the age of tea crop increased from 9, to 21, and to 36 years old, respectively. It seems that tea cultivation is the potential to sequester OC even though the leaves are regularly harvested.