Aluminum species and activity in sandy soil solution with pig slurry addition

Lessandro De Conti,Paulo Ademar Avelar Ferreira,Lincon Oliveira Stefanello Da Silva,Cledimar Rogério Lourenzi,Eduardo Girotto,Gustavo Brunetto,Rogério Piccin,Rafael Da Rosa Couto,Carlos Alberto Ceretta

doi:10.1590/s0100-204x2017001000011

Abstract

Abstract: The objective of this work was to evaluate the effect of pig slurry applications on the exchangeable Al content, activity, and distribution of Al chemical species in the soil solution. Soil samples of a Typic Hapludalf were obtained from an experiment conducted during eight years, with 19 applications of 0, 20, 40, and 80 m3 ha-1 pig slurry. The soil samples were collected in stratified layers to determine exchangeable Al content and to extract the soil solution by the saturated soil paste method. The concentrations of the main cations and anions, dissolved organic carbon, and pH in the soil solution were determined. The distribution of the chemical species of Al and the activity of the Al3+ species were obtained through the Visual Minteq software. The application of pig slurry does not change the exchangeable Al content in the soil and the Al3+ activity in the soil solution. The low Al3+ activity in the topsoil layers does not present risk of toxicity for most crops. Pig slurry applications increase the proportion of the AlHPO4 + and AlSO4 + species in the soil solution, by increasing the concentration of soluble inorganic ligands.

Highlights

Commercial pig farming in Brazil is characterized by confinement in all stages of production, concentrating a large number of animals in small areas, which generates large amounts of waste that need to be discarded
Exchangeable Al was not affected by pig slurry doses, but its contents increased in layers below 0.30 m in all treatments (Figure 1)
The activity of Al3+ in the soil solution was not altered by the application of 0, 20, 40, and 80 m3 ha-1 pig slurry in the studied layers (Figure 1)

Summary

Introduction

Commercial pig farming in Brazil is characterized by confinement in all stages of production, concentrating a large number of animals in small areas, which generates large amounts of waste that need to be discarded. In Rio Grande do Sul, which is the second largest pig farming state in the country, an estimated 38,000 m3 pig slurry (PS) is produced daily (Fepam, 2008) This waste is mainly disposed of by the application in agricultural areas as a source of nutrients to crops (Lourenzi et al, 2013; De Conti et al, 2016). The application of manure or organic waste in agricultural areas modifies the availability of essential and non-essential elements by simultaneously adding numerous chemicals, including carbon. Elements, such as aluminum, may be potentially toxic to plants, even at low concentrations Weathered soils of tropical and subtropical regions are naturally acidic and already have a high content of exchangeable Al, which may be toxic to plants, reducing crop growth and yield (Vieira et al, 2009; Alleoni et al, 2010; Rutkowska et al, 2015)

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