Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv Disentangling the effects of the aqueous matrix on the potential toxicity of liquid pig manure in sub-tropical soils under semi-field conditions Julia Corá Segat a, ⁎ , Dilmar Baretta a , Luís Carlos Iuñes Oliveira Filho b , José Paulo Sousa c , Osmar Klauberg Filho b a Department of Animal Science, Santa Catarina State University (UDESC Oeste), Beloni Trombeta Zanin, 680-E, CEP:89815-630 Chapecó, SC, Brazil b Department of Soil Science, Centre for Agriculture and Veterinary Science, Santa Catarina State University (UDESC-Lages), Lages, Brazil c Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Portugal ARTICLE INFO Keywords: Liquid pig manure Organic fertilization Soil fauna ABSTRACT Inadequate application of liquid pig manure (LPM) may pose risks to the soil due to the potential contaminants that exists, as well as by the large water input that can originate excessive moisture. By using Terrestrial Model Ecosystems, this study aimed to evaluate the effect of application of LPM (82% moisture) using the application rates of 20, 50 and 150 m 3 ha -1 and also of the corresponding amount of water to understand the origin of effects on the soil fauna of two sub-tropical soils. In general, the results obtained for the two soil types indicated that LPM (150 m 3 ha -1 ) changed the composition of soil fauna, with an increase in the abundance of insect larvae and dipterans, but a decrease in the number of earthworms and enchytraeids. Microbial biomass, soil respiration and the nutrients Mg, K and P increased with the amount of LPM supplied to the soil. When analysing the effects of adding large volumes of water via the LPM, results showed that application did not originate significant effects on the parameters measured. The differences obtained when comparing both treatments were mainly attributed to the organic load brought by the LPM and not to the amount of water without LPM. 1. Introduction The current representativeness of Brazilian pig farming worldwide results from the specialization of the productive system, based on technological and organizational advances incorporated in the chain along the last decades. Concomitantly, the increase in the concentration of animals in small areas, lead to a large volume of liquid pig manure (LPM) produced per unit of area, which constitutes one of the greatest environmental problems of this business sector. Currently, the main alternative for the disposal of this residue is its application in agricultural soils as organic fertilizer. This practice in- creases soil organic matter concetration and acts as an important and inexpensive source of nutrients for plant production. Thus, when ade- quately used, pig manure can improve chemical, physical and biolo- gical characteristics of soils (Scherer et al., 2007). However, inadequate and negligent use may generate environmental pollution resulting in already publicly known warnings about the environmental risks of the excessive and/or continuous use of animal wastes as soil fertilizers (Seganfredo, 2017). Studies have shown that the use of LPM causes impacts on soil fauna. A decrease of survival and reproduction of the collembolan species Folsomia candida was reported by Domene et al. (2007) and Maccari et al. (2016) in artificial and sub-tropical soils respectively, as well as a reduction in the reproductive activity and cocoon production of different earthworm species have been found by Murchie et al. (2015). Segat et al. (2015) reported also alterations in the avoidance behaviour, survival and reproduction of the earthworm specie Eisenia andrei exposed to treatments in sub-tropical soils. Moreover, a loss of diversity of edaphic groups in agricultural soils amended by LPM was observed by Alves et al. (2008). However, many gaps of knowledge still exist and the effects of such practice need to be studied to further elucidate the type and magnitude of potential impacts of the use of LPM as fertilizer in crop areas. Besides the relevance of assessing the effects of using LPM on edaphic organisms, it is important to understand what can be causing those effects. The LPM matrix may contain some potential con- taminants, such as metals (Cu and Zn), veterinary products, their me- tabolites and compounds used in animal farming as growth promotors and for the prevention and treatment of diseases. In addition, by being essentially a liquid matrix (over 80% of water) the effects of manure on soil organisms can be caused to a change of the soil habitat, e.g. by physical change of the micro-soil environment or by the excess supply https://doi.org/10.1016/j.ecoenv.2018.10.085 Received 8 May 2018; Received in revised form 21 October 2018; Accepted 23 October 2018 ⁎ Corresponding author. E-mail address: juliasegat@udesc.br (J.C. Segat). Ecotoxicology and Environmental Safety 168 (2019) 457–465 0147-6513/ © 2018 Elsevier Inc. All rights reserved. T