Soil Biology and Biochemistry 147 (2020) 107839 Available online 4 May 2020 0038-0717/© 2020 Elsevier Ltd. All rights reserved. Liming reduces N 2 O emissions from Mediterranean soil after-rewetting and affects the size, structure and transcription of microbial communities Eduardo V� azquez a, 1, ** , Nikola Teutscherova a, b, * , Roberta Pastorelli c , Alessandra Lagomarsino c , Laura Giagnoni d , Giancarlo Renella e a Departamento de Producci� on Agraria, Escuela T� ecnica Superior de Ingeniería Agron� omica, Alimentaria y de Biosistemas, Universidad Polit� ecnica de Madrid, Avda. Puerta de Hierro, E-28040, Madrid, Spain b Department of Crop Sciences and Agroforestry, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamýcka 129 Prague 6-Suchdol, 16500, Czech Republic c Consiglio per le ricerca in agricoltura e l’analisi dell’economia agraria, Research Centre for Agriculture and Environment (CREA-AA), Via di Lanciola, 12/A, 50125, Firenze, FI, Italy d Department of Agriculture, Food, Environment and Forestry, University of Florence, Piazzale delle Cascine, 18, 50144, Firenze, FI, Italy e Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, Legnaro, 35020, Italy A R T I C L E INFO Keywords: Soil liming No-tillage Greenhouse gas emissions Nitrifers Denitrifers Nitrous oxide ABSTRACT In Mediterranean regions, the accumulation of nitrogenous substrates in soil during summer fallow period has been linked to pulses of N 2 O emissions upon soil rewetting. Although the mechanisms of N 2 O emission after soil rewetting have been previously studied, potential mitigation of agronomic practices on N 2 O pulses is still poorly understood. We studied the N 2 O emissions after rewetting of degraded soils managed by no-tillage (NT) and conventional tillage (CT), both with or without lime application under laboratory conditions. The soil was rewetted to 50 and 100% of feld capacity (FC) and the N 2 O fuxes, size, structure and gene transcription of the microbial communities involved in the N 2 O emissions were evaluated. Liming reduced the cumulative N 2 O emission by more than 70 and 65% respect to the unamended soil after soil rewetting to 50% and 100% of FC, respectively, whereas no signifcant effect of tillage on N 2 O emission was observed. Liming strongly infuenced the size and structure of ammonia oxidizing bacteria (AOB) and denitrifer communities, increased the tran- scription of the nirK after soil rewetting, while transcription of genes encoding nitrifcation enzymes was un- detectable. Tillage slightly affected the nitrifer and denitrifer communities, with CT increasing the size of nosZ community. The results indicated that the N 2 O pulse after soil rewetting was caused by denitrifcation rather than nitrifcation. In addition, the increase of nirK transcription suggested that the mitigation of N 2 O emissions observed in limed soils was due to changes in the denitrifcation process, possibly with a higher or more effcient reduction of N 2 O to N 2 . This study showed the potentials of NT and liming management to mitigate the N 2 O emission from degraded Mediterranean soils after soil rewetting due to changes in the effciency of the deni- trifcation process. Our results also showed the usefulness of coupling determinations of gas emission, microbial community structure and gene transcription to clarify the underlying mechanisms of N 2 O emissions from soil. 1. Introduction The summer season in Mediterranean regions is characterized by long periods of drought and hot temperature, which are expected to become more extreme and extended in time in the near future (IPCC, 2014; Varela-Ortega et al., 2016). As these periods are unsuitable for crop cultivation without irrigation, winter crop varieties are sown in autumn after the frst rains and harvested in the spring, leaving the soils uncultivated during summer ( � Alvaro-Fuentes et al., 2009). During such fallow period, drought and high soil temperatures affect C and N cycling, * Corresponding author. Department of Crop Sciences and Aroforestry, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamýck� a 129 Prague 6-Suchdol, 16500, Czech Republic. ** Corresponding author. E-mail addresses: eduardo.vazquez@uni-bayreuth.de (E. V� azquez), teutscherova@ftz.czu.cz (N. Teutscherova). 1 Present Address: Department of Soil Biogeochemistry and Soil Ecology, University of Bayreuth, Dr. Hans-Frisch-Straße 1–3, 95448, Bayreuth, Germany. Contents lists available at ScienceDirect Soil Biology and Biochemistry journal homepage: http://www.elsevier.com/locate/soilbio https://doi.org/10.1016/j.soilbio.2020.107839 Received 8 October 2019; Received in revised form 14 February 2020; Accepted 26 April 2020