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Evaluating the potential of different carbon sources to promote denitrification

Published online by Cambridge University Press:  09 July 2020

J. C. Dlamini*
Affiliation:
Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein9300, South Africa Department of Sustainable Agricultural Sciences, Rothamsted Research, Sustainable Agriculture Sciences, North Wyke, UK Department of Plant and Soil Sciences, University of Pretoria, Private Bag X20, Hatfield0028, South Africa
D. Chadwick
Affiliation:
Environmental Centre Wales, Bangor University, Bangor, UK
J. M. B. Hawkins
Affiliation:
Department of Sustainable Agricultural Sciences, Rothamsted Research, Sustainable Agriculture Sciences, North Wyke, UK
J. Martinez
Affiliation:
National Research Institute of Science and Technology for Environment and Agriculture, Antony, France
D. Scholefield
Affiliation:
Department of Sustainable Agricultural Sciences, Rothamsted Research, Sustainable Agriculture Sciences, North Wyke, UK
Y. Ma
Affiliation:
Environmental Centre Wales, Bangor University, Bangor, UK
L. M. Cárdenas
Affiliation:
Department of Sustainable Agricultural Sciences, Rothamsted Research, Sustainable Agriculture Sciences, North Wyke, UK
*
Author for correspondence: J. C. Dlamini, E-mail: DlaminiJC@ufs.ac.za, jerrydlamini012@gmail.com

Abstract

Organic carbon (C) plays an essential role in the denitrification process as it supplies energy for N2O, N2 and CO2 producing reactions. The objectives of this study were to: (i) rank the reactivity of different C compounds found in manures based on their availability for denitrification and (ii) explore C-quality in different C sources based on their capacity to promote denitrification. Evaluation of different C-sources in promoting denitrification was conducted based on the molar ratio of CO2 production to NO3 reduction after incubation. Results of the first experiment (a 12-day investigation) showed that glucose and glucosamine were highly reactive C compounds with all applied NO3 being exhausted by day 3, and glucosamine had significantly high amount of NH4+-N present at end of the experiment. The glucose and glucosamine treatments resulted in significantly greater cumulative CO2 production, compared to the other treatments. In the second experiment (a 9-day investigation), all NO3 had been depleted by day 6 and 9 from acetic acid and glucose, respectively, and the greatest cumulative CO2 production was from acetic acid. The CO2 appearance to NO3 molar ratios revealed that glucose and glucosamine were compounds with highly available C in the first experiment. In the second experiment, the pig slurry and acetic acid were found to be C-sources that promoted potential denitrification. The application of slurry to soil results in the promotion of denitrification and this depends on the availability of the C compounds it contains. Understanding the relationship between C availability and denitrification potential is useful for developing denitrification mitigation strategies for organic soil amendments.

Type
Crops and Soils Research Paper
Copyright
Copyright © The Author(s), 2020. Published by Cambridge University Press

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