Is Crop Residue Removal to Reduce [N.sub.2]O Emissions Driven by Quality or Quantity? A Field Study and Meta-Analysis

• Published in: Agriculture (Basel) Vol. 10; no. 11
• Main Authors: Essich, Lisa, Nkebiwe, Peteh Mehdi, Schneider, Moritz, Ruser, Reiner
• Format: Journal Article
• Language: English
• Published: MDPI AG 01-11-2020
• Subjects: Air pollution control; Analysis; Denitrification; Nitrous oxide; Germany
• ISSN: 2077-0472; 2077-0472
• DOI: 10.3390/agriculture10110546

In order to quantify the reduction potential for nitrous oxide ([N.sub.2]O) release from arable soils through the removal of crop residues, we conducted an experiment after sugar beet (Beta vulgaris L.) harvest with three treatments: (i) ploughing of the crop residues (+CR:D), (ii) returning residues after ploughing on the surface (+CR:S), and (iii) removal of the residues and ploughing (-CR). [N.sub.2]O fluxes were measured over 120 days in south Germany. High positive correlations between [N.sub.2]O fluxes and the C[O.sub.2] fluxes and soil nitrate contents suggested denitrification as the main [N.sub.2]O source. [N.sub.2]O emissions in +CR:D was higher than in +CR:S (2.39 versus 0.93 kg [N.sub.2]O-N [ha.sup.-1] 120 [d.sup.-1] in +CR:D and +CR:S). Residue removal in -CR reduced the [N.sub.2]O emission compared to +CR:D by 95% and to +CR:S by 87%. We further conducted a meta-analysis on the effect of crop residue removal on [N.sub.2]O emissions, where we included 176 datasets from arable soils with mainly rain fed crops. The overall effect of residue removal showed a [N.sub.2]O reduction of 11%. The highest [N.sub.2]O reduction of 76% was calculated for the removal subgroup with C/N-ratio < 25. Neither the remaining C/N-ratio subgroups nor the grouping variables "tillage" or "residue quantity" differed within their subgroup.