Evaluating the potential of different carbon sources to promote denitrification
Jerry C. Dlamini, David R. Chadwick, J. M. B. Hawkins, José Martínez, D. Scholefield, Yan Ma, L. M. Cárdenas
Abstract
Abstract Organic carbon (C) plays an essential role in the denitrification process as it supplies energy for N 2 O, N 2 and CO 2 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 CO 2 production to NO 3 − 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 NO 3 − being exhausted by day 3, and glucosamine had significantly high amount of NH 4 + -N present at end of the experiment. The glucose and glucosamine treatments resulted in significantly greater cumulative CO 2 production, compared to the other treatments. In the second experiment (a 9-day investigation), all NO 3 − had been depleted by day 6 and 9 from acetic acid and glucose, respectively, and the greatest cumulative CO 2 production was from acetic acid. The CO 2 appearance to NO 3 − 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.