Evolution of organic carbon pools and microbial diversity in hyperarid anthropogenic soils Benedetta Camilli a , Maria Teresa Dell'Abate b , Stefano Mocali c , Arturo Fabiani c , Carmelo Dazzi a, * a Universit a degli Studi di Palermo, Dipartimento di Scienze Agrarie e Forestali, Viale delle Scienze, Ed. 4, 90128 Palermo, Italy b Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Centro di Ricerca per lo Studio delle Relazioni tra Pianta e Suolo, Roma, Italy c Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria, Centro di Ricerca per l'Agrobiologia e la Pedologia, Firenze, Italy article info Article history: Received 17 March 2015 Received in revised form 2 September 2015 Accepted 8 September 2015 Available online xxx Keywords: Soil organic carbon Microbial dynamics Anthropogenic soils Arid environment abstract We investigated the organic carbon pools and the microbial diversity and activity in anthropogenic terraced soils in a desert area of Southern Peru to highlight how the introduction of agriculture in- fluences carbon evolution and storage and genetic and functional diversity of soil microbiota over time. Five sites were selected considering soils cultivated since 5, 15, 20, 35 and 65 years, sampled along the profile depth (0e20 and 20e40 cm layer). Soil and microbial parameters comprised by organic carbon pools, microbial respiration, microbial community physiological profile (CLPP) and microbial diversity (PCR-DGGE) were determined. The results showed that the highest C concentrations were reached after a long cultivation time (P65), at both depths. In this site Corg was mainly composed by chemically not extractable C, considered the most stabilized fraction. The remaining extractable C fraction decreased with the depth and was mainly made up of highly mineralizable compounds. Data showed that human transformations has affected organic carbon pools only after several decades of cultivation, whereas the activity and structure of the microbial community changed gradually over time, showing the major differences between the most ancient (65 years) and the most recent (5 years) anthropized soils. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Anthropogenic soils are becoming an interesting challenge for soil science as the increasing human activities, including agricul- ture, significantly alter soilscape and below ground ecosystems by land use change. In Peru, the development of agriculture dates back to ancient period (Aldenderfer, 1999; Bush et al., 2005; Cardich, 1985; Chepstow-Lusty et al., 1996), but as stressed by Stanish (1991), in the desert areas of Southern Peru, land use change to agriculture and the human modification of original soilscape date back to relatively comparatively recent times (i. e. ~1450 A.D.). The indigenous populations have adopted the levelling of natural slopes (Sandor and Eash, 1995), the building of agricultural terraces and the introduction of irrigation systems as an adaptation strategy to the considerable aridity of the climate (Williams, 2002; Nordt et al., 2004). Over the years, large slope areas have been gradually transformed into stepped arable lands, through extensive soil ex- cavations, displacement and land levelling, with an impressive anthropic impact on the original soilscape. As so deep human changes of landform have occurred, these soils have developed dramatically different properties as compared to their original conditions and therefore they should be recognized as anthropo- genic soils, according to recent tendency in pedology (Dudal et al., 2002; Dazzi and Monteleone, 2007; Dazzi et al., 2009). In particular, introduction of agriculture has drastically changed the natural soilscape of these areas mainly by terracing, largely increased water availability and organic matter inputs, influencing the primary productivity as well as the microbial activity and the carbon cycle (Li et al., 2009; Noe et al., 2012). Land use change from natural to arable agriculture, is considered responsible for a rapid depletion of organic matter in temperate or tropical environments, especially of soluble or labile organic carbon forms. According to Lal (2008) about 30e50% over 50e100 years after conversion to agricultural land use in a temperate climate, and 50e75% over 10e20 years in a tropical climate. However, few studies reported the temporal soil * Corresponding author. E-mail addresses: benedetta.camilli@gmail.com (B. Camilli), mariateresa. dellabate@entecra.it (M.T. Dell'Abate), stefano.mocali@entecra.it (S. Mocali), arturo.fabiani@entecra.it (A. Fabiani), carmelo.dazzi@unipa.it (C. Dazzi). Contents lists available at ScienceDirect Journal of Arid Environments journal homepage: www.elsevier.com/locate/jaridenv http://dx.doi.org/10.1016/j.jaridenv.2015.09.003 0140-1963/© 2015 Elsevier Ltd. All rights reserved. Journal of Arid Environments 124 (2016) 318e331