Carbon sequestration in a nectarine orchard as affected by green manure in China

Information is scarce on long-term effects of green manure on carbon storage in fruit orchards, an important issue for carbon footprinting according to PAS 2050-1 not only in Europe. Thus, for assessing carbon sequestration, the carbon distribution in the vegetation, litter and soil within the same nectarine orchard was compared with three management practices such as sloping plot without conservation measures (T-1), a terraced plot without conservation measures (T-2), and a terraced plot with green manure of Arachis pintoi 'Amarillo' as mulch (T-3), with the following results: (a) carbon storages of fruit tree and litter in the nectarine orchard ranged from 13.0 to 14.7 t carbon ha(-1), and 0.54 to 0.59 kg carbon per plant, respectively. No significant difference was found between different treatments. However, the carbon storage from A. pintoi increased to 5.12 t carbon ha(-1) in the T-3 treatment. (b) Soil organic carbon (SOC) and soil organic carbon density (SOCD) in T-3 treatment significantly increased compared with T-1 and T-2 treatments, and decreased with the increase of soil depth. A significant difference was observed between every soil layers in T-3 treatment. (c) During the 13 years after orchard establishment, the soil organic carbon sources influenced the delta C-13 distribution with depth and carbon originate. The upper soil layer SOC turnover in T3 treatment (a mean 63.1% of replacement in the 0-20 cm soil layer after 13 years) was 1.59 and 1.41 times greater than those of T1 and T-2 treatments, respectively, indicating that terraced nectarine orchard with A. pintoi as green manure could rapidly sequester SOC in subtropical China.