Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

B Gao, T Huang, X Ju, B Gu, W Huang, L Xu, RM Rees, DS Powlson, P Smith, S Cui

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Soil carbon sequestration is being considered as a potential pathway to mitigate climate change. Cropland soils could provide a sink for carbon that can be modified by farming practices, however, they can also act as a source of greenhouse gases (GHG), including not only nitrous oxide (N2O) and methane (CH4), but also the upstream carbon dioxide (CO2) emissions associated with agronomic management. These latter emissions are also sometimes termed “hidden” or “embedded” CO2. In this paper, we estimated the net GHG balance for Chinese cropping systems by considering the balance of soil carbon sequestration, N2O and CH4 emissions, and the upstream CO2 emissions of agronomic management from a life cycle perspective during 2000–2017. Results showed that although soil organic carbon (SOC) increased by 23.2±8.6 Tg C yr−1, the soil N2O and CH4 emissions plus upstream CO2 emissions arising from agronomic management added 269.5±21.1 Tg C‐eq yr−1 to the atmosphere. These findings demonstrate that Chinese cropping systems are a net source of GHG emissions, and that total GHG emissions are about 12 times larger than carbon uptake by soil sequestration. There were large variations between different cropping systems in the net GHG balance ranging from 328 to 7567 kg C‐eq ha−1 yr−1, but all systems act as a net GHG source to the atmosphere. The main sources of total GHG emissions are nitrogen fertilization (emissions during production and application), power use for irrigation, and soil N2O and CH4 emissions. Optimizing agronomic management practices, especially fertilization, irrigation, plastic mulching, and crop residues to reduce total GHG emissions from the whole chain is urgently required in order to develop a low carbon future for Chinese crop production.
Original languageEnglish
Pages (from-to)5590 - 5606
Number of pages17
JournalGlobal Change Biology
Volume24
Issue number12
Early online date17 Aug 2018
DOIs
Publication statusFirst published - 17 Aug 2018

Fingerprint

soil carbon
carbon sequestration
cropping practice
greenhouse gas
soil
carbon
irrigation
mulching
atmosphere
crop residue
nitrous oxide
crop production
management practice
life cycle
carbon dioxide
plastic
methane
organic carbon
climate change

Bibliographical note

1030438

Keywords

  • Agronomic management
  • Life cycle analysis
  • N2O and CH4 emission
  • Net greenhouse gas balance
  • Soil organic carbon
  • Upstream CO2 emissions

Cite this

Gao, B., Huang, T., Ju, X., Gu, B., Huang, W., Xu, L., ... Cui, S. (2018). Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration. Global Change Biology, 24(12), 5590 - 5606. https://doi.org/10.1111/gcb.14425
Gao, B ; Huang, T ; Ju, X ; Gu, B ; Huang, W ; Xu, L ; Rees, RM ; Powlson, DS ; Smith, P ; Cui, S. / Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration. In: Global Change Biology. 2018 ; Vol. 24, No. 12. pp. 5590 - 5606.
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Gao, B, Huang, T, Ju, X, Gu, B, Huang, W, Xu, L, Rees, RM, Powlson, DS, Smith, P & Cui, S 2018, 'Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration' Global Change Biology, vol. 24, no. 12, pp. 5590 - 5606. https://doi.org/10.1111/gcb.14425

Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration. / Gao, B; Huang, T; Ju, X; Gu, B; Huang, W; Xu, L; Rees, RM; Powlson, DS; Smith, P; Cui, S.

In: Global Change Biology, Vol. 24, No. 12, 17.08.2018, p. 5590 - 5606.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Chinese cropping systems are a net source of greenhouse gases despite soil carbon sequestration

AU - Gao, B

AU - Huang, T

AU - Ju, X

AU - Gu, B

AU - Huang, W

AU - Xu, L

AU - Rees, RM

AU - Powlson, DS

AU - Smith, P

AU - Cui, S

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N2 - Soil carbon sequestration is being considered as a potential pathway to mitigate climate change. Cropland soils could provide a sink for carbon that can be modified by farming practices, however, they can also act as a source of greenhouse gases (GHG), including not only nitrous oxide (N2O) and methane (CH4), but also the upstream carbon dioxide (CO2) emissions associated with agronomic management. These latter emissions are also sometimes termed “hidden” or “embedded” CO2. In this paper, we estimated the net GHG balance for Chinese cropping systems by considering the balance of soil carbon sequestration, N2O and CH4 emissions, and the upstream CO2 emissions of agronomic management from a life cycle perspective during 2000–2017. Results showed that although soil organic carbon (SOC) increased by 23.2±8.6 Tg C yr−1, the soil N2O and CH4 emissions plus upstream CO2 emissions arising from agronomic management added 269.5±21.1 Tg C‐eq yr−1 to the atmosphere. These findings demonstrate that Chinese cropping systems are a net source of GHG emissions, and that total GHG emissions are about 12 times larger than carbon uptake by soil sequestration. There were large variations between different cropping systems in the net GHG balance ranging from 328 to 7567 kg C‐eq ha−1 yr−1, but all systems act as a net GHG source to the atmosphere. The main sources of total GHG emissions are nitrogen fertilization (emissions during production and application), power use for irrigation, and soil N2O and CH4 emissions. Optimizing agronomic management practices, especially fertilization, irrigation, plastic mulching, and crop residues to reduce total GHG emissions from the whole chain is urgently required in order to develop a low carbon future for Chinese crop production.

AB - Soil carbon sequestration is being considered as a potential pathway to mitigate climate change. Cropland soils could provide a sink for carbon that can be modified by farming practices, however, they can also act as a source of greenhouse gases (GHG), including not only nitrous oxide (N2O) and methane (CH4), but also the upstream carbon dioxide (CO2) emissions associated with agronomic management. These latter emissions are also sometimes termed “hidden” or “embedded” CO2. In this paper, we estimated the net GHG balance for Chinese cropping systems by considering the balance of soil carbon sequestration, N2O and CH4 emissions, and the upstream CO2 emissions of agronomic management from a life cycle perspective during 2000–2017. Results showed that although soil organic carbon (SOC) increased by 23.2±8.6 Tg C yr−1, the soil N2O and CH4 emissions plus upstream CO2 emissions arising from agronomic management added 269.5±21.1 Tg C‐eq yr−1 to the atmosphere. These findings demonstrate that Chinese cropping systems are a net source of GHG emissions, and that total GHG emissions are about 12 times larger than carbon uptake by soil sequestration. There were large variations between different cropping systems in the net GHG balance ranging from 328 to 7567 kg C‐eq ha−1 yr−1, but all systems act as a net GHG source to the atmosphere. The main sources of total GHG emissions are nitrogen fertilization (emissions during production and application), power use for irrigation, and soil N2O and CH4 emissions. Optimizing agronomic management practices, especially fertilization, irrigation, plastic mulching, and crop residues to reduce total GHG emissions from the whole chain is urgently required in order to develop a low carbon future for Chinese crop production.

KW - Agronomic management

KW - Life cycle analysis

KW - N2O and CH4 emission

KW - Net greenhouse gas balance

KW - Soil organic carbon

KW - Upstream CO2 emissions

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DO - 10.1111/gcb.14425

M3 - Article

VL - 24

SP - 5590

EP - 5606

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

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ER -