title: Stimulation of N2O emission by manure application to agricultural soils may largely offset carbon benefits: a global meta-analysis.
abstract: Animal manure application as organic fertilizer does not only sustain agricultural productivity and increase soil organic carbon (SOC) stocks, but also affects soil nitrogen cycling and nitrous oxide (N2O) emissions. However, given that the sign and magnitude of manure effects on soil N2O emissions is uncertain, the net climatic impact of manure application in arable land is unknown. Here, we performed a global meta-analysis using field experimental data published in peer-reviewed journals prior to December 2015. In this meta-analysis, we quantified the responses of N2O emissions to manure application relative to synthetic N fertilizer application from individual studies and analyzed manure characteristics, experimental duration, climate, and soil properties as explanatory factors. Manure application significantly increased N2O emissions by an average 32.7% (95% confidence interval: 5.1-58.2%) compared to application of synthetic N fertilizer alone. The significant stimulation of N2O emissions occurred following cattle and poultry manure applications, subsurface manure application, and raw manure application. Furthermore, the significant stimulatory effects on N2O emissions were also observed for warm temperate climate, acid soils (pH < 6.5), and soil texture classes of sandy loam and clay loam. Average direct N2O emission factors (EFs) of 1.87% and 0.24% were estimated for upland soils and rice paddy soils receiving manure application, respectively. Although manure application increased SOC stocks, our study suggested that the benefit of increasing SOC stocks as GHG sinks could be largely offset by stimulation of soil N2O emissions and aggravated by CH4emissions if, particularly for rice paddy soils, the stimulation of CH4emissions by manure application was taken into account.
authors.affiliation: Institute of Bio- and Geosciences - Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.|Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, 610041, Chengdu, China.
authors.forename: Minghua
authors.identifier: 0000-0002-0003-2892
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, 610041, Chengdu, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 550081, Guiyang, China.|Puding Karst Ecosystem Observation and Research Station, Anshun, 561000, Guizhou, China.
authors.forename: Shijie
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Surveying and Planning, Shangqiu Normal University, 476000, Henan, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Institute of Bio- and Geosciences - Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
authors.forename: Harry
authors.initials: H
authors.lastname: Vereecken
authors.affiliation: Institute of Bio- and Geosciences - Agrosphere (IBG-3), Forschungszentrum Jülich GmbH, 52425, Jülich, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Brüggemann
mesh_terms: D000383:Agriculture; D000818:Animals; D002244:Carbon; D057486:Carbon Cycle; D002417:Cattle; D005308:Fertilizers; D008372:Manure; D009609:Nitrous Oxide; D012987:Soil
chemical_list: D005308:Fertilizers; D008372:Manure; D012987:Soil; D002244:Carbon; D009609:Nitrous Oxide
keywords: animal manure; emission factor; greenhouse gas balance; manure characteristics; meta-analysis; nitrous oxide; soil pH; soil texture