Lime and gypsum application increases biological activity, carbon pools, and agronomic productivity in highly weathered soil Thiago Massao Inagaki a , João Carlos de Moraes Sá b, *, Eduardo Fávero Caires b , Daniel Ruiz Potma Gonçalves a a Graduate Program in Agronomy, Universidade Estadual of Ponta Grossa, Av. Carlos Cavalcanti 4748, Campus de Uvaranas, 84030-900, Ponta Grossa, Paraná, Brazil b Department of Soil Science and Agricultural Engineering, Universidade Estadual of Ponta Grossa, Av. Carlos Cavalcanti 4748, Campus de Uvaranas, 84030- 900, Ponta Grossa, Paraná, Brazil A R T I C L E I N F O Article history: Received 1 February 2016 Received in revised form 16 June 2016 Accepted 20 June 2016 Available online xxx Keywords: Soil acidity Carbon sequestration Soil aggregation Soil biology Soil organic matter A B S T R A C T The application of lime and gypsum has been recognized as an important strategy for correcting soil acidity and for improving soil fertility, soil aggregation, and agronomic productivity in highly weathered soils. We hypothesized that the combined application of lime and gypsum would create favorable conditions for biological activity and result in increased SOC storage and agronomic productivity. Thus, the aim of this study was to evaluate the long-term (i.e., 15 years) impact of lime and gypsum application on the biological activity, SOC stocks, and agronomic productivity of plots under no-till soil management. The experiment was established in 1998 at a site with clayey Oxisol in southern Brazil, and was designed with a split-plot arrangement, completely randomized blocks, and three replicates. The main plot was subject to three lime treatments: (i) control (no lime); (ii) incorporated lime (IL):incorporation of 4.5 Mg lime ha 1 to a depth of 0–20 cm by; and (iii) surface lime (SL): surface application of 4.5 Mg lime ha 1 , which was equally divided among three annual applications during the first three years of the experiment. The subplots were comprised by surface applications of gypsum at 0, 3, 6, or 9 Mg ha 1 . Soil samples were collected in 1998, before of the experiment, and in October 2013, in order to evaluate soil enzyme activities, SOC pool stocks, crop productivity, C-biomass input, and soil fertility attributes. Both forms of lime application significant improved the stocks of several SOC pools, crop productivity, biomass-C input rates, soil fertility attributes, and enzyme activity. The SOC stocks were positively correlated with Ca 2+ content and biomass-C input, demonstrating the potential of calcium to improve C accumulation. Enzyme activities were significantly affected by both soil fertility and SOC pools, with increases in hot water extractable organic C yielding the greatest increases in enzyme activity. In addition, we also found that gypsum application significantly increased the stocks of labile SOC pools and arylsulfatase activity. However, effects of gypsum application were less apparent than those of lime application and the combination of surface lime (4.5 Mg ha 1 ) and gypsum (9 Mg ha 1 ) application yielded the greatest long-term increase in the stock of total organic C stock. Thus, the results of the present study suggest that lime and gypsum application, along with no-till management and biomass-C input, constitutes an efficient strategy for improving the biological activity, C stocks, and productivity of agricultural soils. ã 2016 Elsevier B.V. All rights reserved. 1. Introduction The improvement of soil aggregation is one of the main strategies for increasing C sequestration in highly weathered soils, and in the soils of tropical and subtropical native forests, C stocks are mainly governed by clay content and the presence of iron and aluminum oxides, which are considered major soil aggregating agents (Tisdall and Oades, 1982). However, when native vegetation is converted to agricultural systems, changes occur in the soil Abbreviations: BS, base saturation; HWEOC, hot water extractable organic carbon; IL, incorporated lime; MAOC, mineral associated organic carbon; POC, particulate organic carbon; POXC, permanganate oxidizable organic carbon; SL, surface lime; SOC, soil organic carbon; TOC, total organic carbon. * Corresponding author. E-mail address: jcmsa@uepg.br (J.C. de Moraes Sá). http://dx.doi.org/10.1016/j.agee.2016.06.034 0167-8809/ã 2016 Elsevier B.V. All rights reserved. Agriculture, Ecosystems and Environment 231 (2016) 156–165 Contents lists available at ScienceDirect Agriculture, Ecosystems and Environment journa l homepage : www.e lsevier.com/loca te/agee