title: Soil organic carbon of an intensively reclaimed region in China: Current status and carbon sequestration potential.
abstract: Land reclamation has been highly intensive in China, resulting in a large amount of soil organic carbon (SOC) loss to the atmosphere. Evaluating the factors which drive SOC dynamics and carbon sequestration potential in reclaimed land is critical for improving soil fertility and mitigating global warming. This study aims to determine the current status and factors important to the SOC density in a typical reclaimed land located in Eastern China, where land reclamation has been undergoing for centuries. A total of 4746 topsoil samples were collected from 2007 to 2010. The SOC density of the reclaimed land (3.18±0.05kgCm(-2); mean±standard error) is significantly lower than that of the adjacent non-reclaimed land (5.71±0.04kgCm(-2)) (p<0.05). A Random Forest model is developed and it captures the relationships between the SOC density and the environmental/anthropogenic factors (R(2)=0.59). The soil pH, land use, and elevation are the most important factors for determining SOC dynamics. In contrast, the effect of the reclamation age on the SOC density is negligible, where SOC content in the land reclaimed during years 1047-1724 is as low as that reclaimed during years 1945-2004. The scenario analysis results indicate that the carbon sequestration potential of the reclaimed lands may achieve a maximum of 5.80±1.81kgCO2m(-2) (mean±SD) when dryland is converted to flooded land with vegetable-rice cropping system and soil pH of ~5.9. Note that in some scenarios the methane emission substantially offsets the carbon sequestration potential, especially for continuous rice cropping system. With the optimal setting for carbon sequestration, it is estimated that the dryland reclaimed in the last 50years in China is able to sequester 0.12milliontons CO2 equivalent per year.
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China.
authors.forename: Xunfei
authors.initials: X
authors.lastname: Deng
authors.affiliation: Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Zhejiang Provincial Key Laboratory of Organic Pollution Processes and Control, Hangzhou, Zhejiang 310058, China. Electronic address: yzhan@zju.edu.cn.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhan
authors.affiliation: Station of Planting Industry Management of Ningbo city, Ningbo, Zhejiang 315012, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China.
authors.forename: Wanzhu
authors.initials: W
authors.lastname: Ma
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China.
authors.forename: Zhouqiao
authors.initials: Z
authors.lastname: Ren
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China.
authors.forename: Xiaojia
authors.initials: X
authors.lastname: Chen
authors.affiliation: Station of Planting Industry Management of Ningbo city, Ningbo, Zhejiang 315012, China.
authors.forename: Fangjin
authors.initials: F
authors.lastname: Qin
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Long
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China; College of Environmental and Resource Sciences, Zhejiang Agriculture and Forest University, Hangzhou, Zhejiang 311300, China.
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Zhu
authors.affiliation: Institute of Digital Agriculture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang 310021, China. Electronic address: luxn@mail.zaas.ac.cn.
authors.forename: Xiaonan
authors.initials: X
authors.lastname: Lv
keywords: Carbon sequestration; Land reclamation; Land use; Soil organic carbon; Soil pH