Effects of slurry acidification on soil N2O fluxes and denitrification. Issue 6 (18th October 2021)

• Record Type: Journal Article
• Authors: Malique, Francois; Wangari, Elizabeth; Andrade‐Linares, Diana Rocío; Schloter, Michael; Wolf, Benjamin; Dannenmann, Michael; Schulz, Stefanie; Butterbach‐Bahl, Klaus
• Is Part Of: Journal of plant nutrition and soil science. Volume 184:Issue 6(2021)
• Page Start: 696
• Page End: 708
• Publication Date: 2021-10-18
• Subjects: methanogens -- nitrite reducers -- nitrous oxide reducers -- potential denitrification -- slurry acidification; Plants -- Nutrition -- Periodicals; Soil science -- Periodicals; 630
• DOI: 10.1002/jpln.202100095
• Languages: English
• ISSNs: 1436-8730

Abstract

Abstract: Background: Reductions of ammonia volatilization resulting from slurry applications to intensively managed grassland may be achieved via slurry acidification. However, it remains uncertain if this may result in pollution swapping, that is, due to reduced ammonia volatilization and increased soil N availability, emission of nitrous oxide from soils may increase. Aims: In this study, we compared control (no fertilizer) and slurry fertilized grassland treatments [not acidified (S) and acidified (AS)] to assess whether slurry acidification results in changes of soil N availability, denitrification potential and activity as well as soil fluxes of nitrous oxide. Methods: The study was carried out in a montane grassland system in southern Germany, and parameters were followed over a 43‐days period with continuous measurements of soil GHG fluxes and biweekly measurements of microbial and soil parameters preceding and following two fertilizing events. Results: Over the entire observation period cumulative N2 O emissions were significantly elevated for treatments receiving slurry applications, with differences between acidified and non‐acidified slurry treatments being overall insignificant. Transcripts of the nirK type nitrite reductase showed significantly higher numbers in soils of the AS treatment. While soil potential denitrification rates (PDR) did not differ between treatments, there was a strong tendency of increased PDRs for the AS treatment. Conclusions: Against expectation, we did not find that application of AS affects PDR or soil N2 O emissions significantly, though in tendency higher rates of soil N2 O emissions as well as higher potential denitrification rates were found in treatments receiving acidified slurry as compared to the slurry only treatment. Our results indicate that longer observation periods and given the significant spatial variability, higher numbers of replicates are needed, to finally assess if slurry application indeed results in increased soil denitrification activity, soil N2 O production and soil‐atmosphere N2 O emissions.