title: Characteristics of differently stabilised soil organic carbon fractions in relation to long-term fertilisation in Brown Earth of Northeast China.
abstract: Long-term use of artificial fertiliser has a significant impact on soil organic carbon (SOC). We used physical-chemical fractionation methods to assess the impact of long-term (26years) fertilisation in a maize cropping system developed on Brown Earth in Northeast China. Plot treatments consisted of control (CK); nitrogen (N) fertiliser (N2); low-level organic manure combined with inorganic N and phosphorus (P) fertiliser (M1N1P1); medium-level organic manure combined with inorganic N fertiliser (M2N2); and high-level organic manure combined with inorganic N and P fertiliser (M4N2P1). Our objectives were to (1) determine the contents of and variations in the SOC fractions; (2) explore the relationship between total SOC and its fractions. In treatments involving organic manure (M1N1P1, M2N2, and M4N2P1), total SOC and physically protected microaggregate (μagg) and μagg occluded particulate organic carbon (iPOC) contents increased by 9.9-58.9%, 1.3-34.7%, 29.5-127.9% relative to control, respectively. But there no significant differences (P>0.05) were detected for the chemically, physically-chemically, and physically-biochemically protected fractions among the M1N1P1, M2N2, and M4N2P1 treatments. Regression analysis revealed that there was a linear positive correlation between SOC and the unprotected coarse particulate organic carbon (cPOC), physically protected μagg, and iPOC fractions (P<0.05). However, physically-chemically, and physically-biochemically protected fractions responded negatively to SOC content. The highest rate of C accumulation among the SOC fractions occurred in the cPOC fraction, which accounted for as much as 32% of C accumulation as total SOC increased, suggesting that cPOC may be the most sensitive fraction to fertiliser application. We found that treatments had no effect on C levels in H-μsilt and NH-μsilt, indicating that the microaggregated silt C-fractions may have reached a steady state in terms of C saturation in the Brown Earth of Northeast China.
authors.affiliation: Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture; College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, China; National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Xiangru
authors.initials: X
authors.lastname: Xu
authors.affiliation: National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China. Electronic address: zhangwenju01@caas.cn.
authors.forename: Wenju
authors.initials: W
authors.lastname: Zhang
authors.affiliation: National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Minggang
authors.initials: M
authors.lastname: Xu
authors.affiliation: Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture; College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, China.
authors.forename: Shuangyi
authors.initials: S
authors.lastname: Li
authors.affiliation: Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture; College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: An
authors.affiliation: Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture; College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, China.
authors.forename: Jiubo
authors.initials: J
authors.lastname: Pei
authors.affiliation: National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Xiao
authors.affiliation: Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning 110164, China.
authors.forename: Hongtu
authors.initials: H
authors.lastname: Xie
authors.affiliation: Key Laboratory of Arable Land Conservation (Northeast China), Ministry of Agriculture; College of Land and Environment, Shenyang Agricultural University, Shenyang, Liaoning 110866, China. Electronic address: j-kwang@163.com.
authors.forename: Jingkuan
authors.initials: J
authors.lastname: Wang
keywords: Brown Earth; Carbon sequestration; Long-term fertilisation; Soil organic carbon; Stabilisation mechanism