2.5.
Soil
organic carbon
measurement
Soil at the depth of 0~5cm, 5~20 cm,
20~80 cm, 80~140cm,
140~200cm was sampled
using a 5cm diameter soil
corer with 3 subsamples in each plot, mixed, air-dried, grinded and
sieved for
soil
organic carbon (SOC)
measurement. The SOC was
measured by the potassium dichromate external heating method (Springer
& Klee, 2010).