Multi-experiment assessment of soil nitrous oxide emissions in sugarcane

M V Galdos; J R Soares; K S Lourenço; P Harris; M Zeri; G Cunha-Zeri; V P Vargas; I A M Degaspari; H Cantarella

doi:10.1007/s10705-023-10321-w

Multi-experiment assessment of soil nitrous oxide emissions in sugarcane

Nutr Cycl Agroecosyst. 2023;127(3):375-392. doi: 10.1007/s10705-023-10321-w. Epub 2023 Oct 21.

Authors

M V Galdos¹, J R Soares², K S Lourenço³, P Harris⁴, M Zeri⁵, G Cunha-Zeri⁶, V P Vargas³, I A M Degaspari³, H Cantarella³

Affiliations

¹ Rothamsted Research, Sustainable Soils and Crops, Harpenden, AL5 2JQ UK.
² School of Agricultural Engineering (FEAGRI), University of Campinas (UNICAMP), Av. Cândido Rondon, 501, Campinas, SP 13083-875 Brazil.
³ Soils and Environmental Resources Centre, Agronomic Institute of Campinas (IAC), Av. Barao de Itapura 1481, Campinas, SP 13020-902 Brazil.
⁴ Rothamsted Research, Net Zero and Resilient Farming, North Wyke, Okehampton, Devon, EX20 2SB UK.
⁵ National Center for Monitoring and Early Warning of Natural Disasters (Cemaden), São José dos Campos, Brazil.
⁶ National Institute for Space Research (INPE), São José dos Campos, Brazil.

Abstract

Soil nitrous oxide (N₂O) fluxes comprise a significant part of the greenhouse gas emissions of agricultural products but are spatially and temporally variable, due to complex interactions between climate, soil and management variables. This study aimed to identify the main factors that affect N₂O emissions under sugarcane, using a multi-site database from field experiments. Greenhouse gas fluxes, soil, climate, and management data were obtained from 13 field trials spanning the 2011-2017 period. We conducted exploratory, descriptive and inferential data analyses in experiments with varying fertiliser and stillage (vinasse) type and rate, and crop residue rates. The most relevant period of high N₂O fluxes was the first 46 days after fertiliser application. The results indicate a strong positive correlation of cumulative N₂O with nitrogen (N) fertiliser rate, soil fungi community (18S rRNA gene), soil ammonium (NH₄⁺) and nitrate (NO₃^-); and a moderate negative correlation with amoA genes of ammonia-oxidising archaea (AOA) and soil organic matter content. The regression analysis revealed that easily routinely measured climate and management-related variables explained over 50% of the variation in cumulative N₂O emissions, and that additional soil chemical and physical parameters improved the regression fit with an R² = 0.65. Cross-wavelet analysis indicated significant correlations of N₂O fluxes with rainfall and air temperature up to 64 days, associated with temporal lags of 2 to 4 days in some experiments, and presenting a good environmental control over fluxes in general. The nitrogen fertiliser mean emission factors ranged from 0.03 to 1.17% of N applied, with urea and ammonium nitrate plus vinasse producing high emissions, while ammonium sulphate, ammonium nitrate without vinasse, calcium nitrate, and mitigation alternatives (nitrification inhibitors and timing of vinasse application) producing low N₂O-EFs. Measurements from multiple sites spanning several cropping seasons were useful for exploring the influence of environmental and management-related variables on soil N₂O emissions in sugarcane production, providing support for global warming mitigation strategies, nitrogen management policies, and increased agricultural input efficiency.

Supplementary information: The online version contains supplementary material available at 10.1007/s10705-023-10321-w.

Keywords: Bioenergy; Brazil; Emission factors; Mitigation; Nitrogen cycling.

Abstract

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