Amelioration of soil acidity and soybean yield after surface lime reapplication to a long-term no-till integrated crop-livestock system under varying grazing intensities Amanda Posselt Martins a, *, Ibanor Anghinoni a , Sérgio Ely V.G.de Andrade Costa a , Filipe Selau Carlos a , Gabriela de Holanda Nichel a , Rodrigo André Pereira Silva a , Paulo César de Faccio Carvalho b a Department of Soil Science, Federal University of Rio Grande do Sul, PO Box 15100, Porto Alegre, RS 91540-000, Brazil b Department of Forage Plants and Agrometeorology, Federal University of Rio Grande do Sul, Porto Alegre, RS,Brazil A R T I C L E I N F O Article history: Received 4 December 2013 Received in revised form 1 May 2014 Accepted 29 July 2014 Keywords: pH Base saturation Aluminum saturation Liming Integrated systems A B S T R A C T An integrated crop-livestock system (ICLS), with summer grain cropping and winter grazing of cover crops, is an option for agricultural management in subtropical areas. Despite numerous studies evaluating ICLS, there have been limited investigations of soil acidity and lime application dynamics in such systems. Because grain producers resist introducing livestock into cultivation areas due to fear of negative impacts of grazing on soybean yields and lime movement thorough the soil profile, the objective of this research is to evaluate the impacts of surface lime reapplication on the amelioration of soil acidity attributes and the yield of soybean in a long-term integrated soybean-beef cattle system under no-till under varying grazing intensities. An experiment was established in 2001 for an ICLS on a Rhodic Hapludox soil. Crop succession consisted of soybean (Glycine max) cultivation during summer and a mix of black-oat (Avena strigosa) + Italian ryegrass (Lolium multiflorum) during winter. Treatments consisted of varying grazing intensities during winter: intensive grazing, moderate grazing, and no-grazing. Lime was applied to the surface of the entire area at the beginning of the experiment, and a reapplication was performed nine years later (May of 2010) in a sub-parcel scheme (with and without lime reapplication). Soil acidity attributes (pH, base saturation and aluminum saturation) were evaluated at 12, 18, 24, and 30 months after lime reapplication, and the soybean yields of the 2010/11, 2011/12, and 2012/13 seasons were measured. As previously observed for the first surface lime application performed in the same trial area, the present study demonstrated that ICLS, regardless of grazing intensity, did not inhibit soil improvement in deeper layers after surface lime reapplication. In fact, the presence of animals helps to ameliorate soil acidity in deeper layers, compared to non-grazed areas. The soybean yield was not correlated with the soil acidity attributes and was affected by lime reapplication only under intensive grazing and drought conditions. However, when summer rainfall was lower than the expected climatological normal, soybean yields were higher in non-grazed areas. ã 2014 Elsevier B.V. All rights reserved. 1. Introduction Surface lime (re)application remains a controversial topic regarding food production system management. The efficiency of this agronomic practice to correct soil acidity in the soil profile under no-tillage (NT) systems has been widely studied because the reacidification process can result in a greater increase in soil acidity in deeper soil layers compared to the upper layers (Tang and Rengel, 2003). Varying results of the effects of surface liming on the soil profile have been observed, with liming affecting soil layers to depths of only 5 cm(Rheinheimer et al., 2000; Amaral et al., 2004a) as well as soil layers of 40 cm or deeper (Oliveira and Pavan, 1996; Caires et al., 2008). According to Edmeades and Ridley, (2003) such differences exist because, in addition to the effects of the liming rate and time, several other factors affect this dynamic, such as: rainfall distribu- tion, soil texture, structure (presence of macro and biopores), hydraulic conductivity, fauna (which mix soil layers), crop rotation and management, and residue additions, among others. Additionally, the yield responses of crops to surface liming are not clear because the degree of impact depends on all the * Corresponding author. Tel.: +55 51 3308 7420. E-mail address: amandaposselt@gmail.com (A.P. Martins). http://dx.doi.org/10.1016/j.still.2014.07.019 0167-1987/ ã 2014 Elsevier B.V. All rights reserved. Soil & Tillage Research 144 (2014) 141–149 Contents lists available at ScienceDirect Soil & Tillage Research journa l homepage: www.e lsevier.com/locate/st ill