Vertical distribution of soil carbon and nutrient storages under a Michelia macclurei plantation

Carbon and nutrient storages in different soil layers were studied in a 10-years-old Michelia macclurei plantation, in order to understand the soil carbon sequestration capacity and nutrient status of the M. macclurei plantation.

Five-point sampling method was used to collect soil samples from 0−20, 20−40, 40−60, 60−80 and 80−100 cm depth layers. Soil pH, contents of organic matter, total N, total P, total K, alkalized N, available P and rapidly available K were determined by routine methods. Carbon and nutrient storages were calculated.

Soil under M. macclurei plantation was acidic (pH3.54−3.79). Soil carbon content ofM. macclurei plantation decreased with the increase of soil depth. There was no significant difference in total P and K contents among different soil layers, while the contents of total N, alkalized N, available P and rapidly available K decreased with the increase of soil depth. Soil carbon storage of M. macclurei plantation in 0−100 cm depth layer was 259.26 t·hm⁻². The storages of soil N, P and K in 0−100 cm depth layer were 21.50, 7.47 and 209.42 t·hm⁻², respectively. Soil carbon, P and K storages of each layer increased with increasing soil depth.

Soil carbon storage of M. macclurei plantation is higher than the average level over all the nation, indicating that the soil in this stand has higher carbon sink potential and ability of improving the soil. There are more soil carbon, P and K storages in deeper layer than in soil surface, indicating poor carbon sequestration capacity and severe leaching erosion in surface soil. It is suggested that in the future management, attention should be paid to prevent soil erosion and enhance the carbon sequestration capacity of surface soil.