Contents lists available at ScienceDirect European Journal of Soil Biology journal homepage: www.elsevier.com/locate/ejsobi Effects of corn stover management on soil quality Julen Urra a,* , Iker Mijangos a , Anders Lanzén a , Jaume Lloveras b , Carlos Garbisu a a NEIKER-Tecnalia, Department of Conservation of Natural Resources, Soil Microbial Ecology Group, c/ Berreaga 1, E-48160 Derio, Spain b University of Lleida, Av. Rovira Roure 191, E-25198 Lleida, Spain ARTICLE INFO Handling editor: Bryan Griffiths Keywords: Agricultural residue management Agricultural sustainability Organic amendment Soil health Soil microorganisms ABSTRACT The incorporation of stover into soil can bring beneficial effects in terms of soil fertility, stabilization of soil structure, maintenance of soil organic carbon, etc. We evaluated the effects, after 6 years of consecutive treatment, of corn stover incorporation versus corn stover removal on soil quality, using physicochemical and biological parameters as indicators of soil quality. Throughout the experimental period, soil organic carbon decreased as a result of stover removal (from 20.1 to 14.7 g kg -1 ). Substrate-induced respiration and bacterial gene abundance decreased by stover removal over the same period (24.0 and 47.6%, respectively). Biolog EcoPlates™ data showed faster rates of D-xylose and D-mannitol utilization by the soil bacterial communities under stover incorporation. 16 S and 18 S rRNA Illumina sequencing data did not show significant differences in terms of microbial diversity and composition between stover incorporation and stover removal treatments. Finally, the incorporation of stover resulted in higher values (27.2% higher) of soil quality, as reflected by the value of a Soil Quality Index, which integrates the values of a variety of microbial indicators of soil quality. In conclusion, incorporation of stover after corn harvest is a beneficial agronomic practice which enhances soil N and C pools and stimulates microbial communities, leading to an increase in soil quality. 1. Introduction Corn (Zea mays L.) stover has been identified as potential feedstock for cellulosic ethanol production because of its high cellulosic content, large volume of biomass production and wide availability around the world [54]. However, the removal of stover can lead to a decline in soil quality and, hence, agricultural productivity by decreasing the content of soil organic carbon (SOC) and increasing the risk of soil erosion [3,17,30]. Conversely, incorporation of stover into agricultural soil can improve soil quality through a variety of processes such as stabilization of soil structure, prevention of soil erosion, maintenance of SOC, nu- trient recycling, provision of energy for soil microbial communities, etc. Soil microorganisms play an essential role in soil functioning and the delivery of soil ecosystem services. Thus, soil microbial parameters related to the activity, biomass and diversity of soil microbial com- munities are frequently used as indicators of soil quality [10,40], owing to their sensitivity, fast response, integrative character and ecological relevance. Nonetheless, there are limited reports on the effects of stover incorporation versus stover removal on soil microbial communities. Lehman et al. [26] reported a reduction in the fungi-to-bacteria ratio as a result of the removal of stover. Johnson et al. [17] found a decrease in soil enzyme activities after three consecutive cycles of stover removal. Moebius-Clune et al. [35] observed a reduction in decomposition activity and glomalin concentration in soil after 32 years of stover re- moval. In contrast, the long-term incorporation of stover has been found to increase soil microbial biomass [12,48]. The aim of this work was to evaluate the effects of six years of corn stover incorporation versus corn stover removal on agricultural soil quality, with special emphasis on the changes induced in soil microbial parameters that provide information on the activity, biomass and di- versity of soil microorganisms. In particular, there is limited informa- tion on the changes induced by stover management on soil microbial diversity and composition. Recent developments in sequencing tech- nologies have facilitated the sequencing of the genomes of soil micro- bial communities. Therefore, 16 S and 18 S rRNA gene-based Illumina sequencing were used to study differences between soil microbial communities subject to stover incorporation versus stover removal. We hypothesized that, after six years, the incorporation of corn stover from agricultural fields would positively impact soil quality by increasing soil organic carbon and stimulating soil microbial communities. 2. Materials and methods 2.1. Experimental design A field experiment was conducted in Almacelles (NE Spain, 41º43′ https://doi.org/10.1016/j.ejsobi.2018.06.005 Received 7 March 2018; Received in revised form 8 June 2018; Accepted 28 June 2018 * Corresponding author. NEIKER-Tecnalia, Department of Conservation of Natural Resources, Soil Microbial Ecology Group, c/ Berreaga 1, E-48160 Derio, Spain. E-mail address: jurra@neiker.eus (J. Urra). European Journal of Soil Biology 88 (2018) 57–64 1164-5563/ © 2018 Elsevier Masson SAS. All rights reserved. T