Forms and accumulation of copper and zinc in a sandy typic hapludalf soil after long-term application of pig slurry and deep litter

Tadeu Luis Tiecher,Lucas Benedet,Paulo Ademar Avelar Ferreira,Eduardo Girotto,Rafael Da Rosa Couto,Carlos Alberto Ceretta,Alcione Miotto,Cledimar Rogério Lorenzi,Gustavo Brunetto,Jucinei José Comin,Marcel Pires De Moraes

doi:10.1590/s0100-06832013000300028

Abstract

Successive applications of pig slurry and pig deep litter may lead to an accumulation of copper (Cu) and zinc (Zn) fractions in the soil profile. The objective of this study was to evaluate the Cu and Zn forms and accumulation in a Sandy Typic Hapludalf soil after long-term application of pig slurry and deep litter. In March 2010, eight years after initiating an experiment in Braço do Norte, Santa Catarina (SC), Brazil, on a Sandy Typic Hapludalf soil, soil samples were collected from the 0-2.5, 2.5-5.0, 5-10 and 10-15 cm layers in treatments consisting of no manure application (control) and with applications of pig slurry and deep litter at two levels: the single and double rate of N requirement for maize and black oat succession. The soil was dried, ground in an agate mortar and analyzed for Cu and Zn contents by 0.01 mol L-1 EDTA and chemically fractionated to determine Cu and Zn. The applications of Pig deep litter and slurry at doses equivalent to 90 kg ha-1 N increased the contents of available Cu and Zn in the surface soil layer, if the double of this dose was applied in pig deep litter or double this dose in pig slurry, Cu and Zn migrated to a depth of 15 cm. Copper is accumulated mainly in the organic and residual fractions, and zinc preferentially in the fraction linked to clay minerals, especially in the surface soil layers.

Highlights

Pig slurry, generated from washing out the stalls with water, and pig deep litter, a residue from raising pigs on a layer of organic material, normally consisting of wood chips or straw from crops, has been used as a source of nutrients for crops in management systems such as no-tillage
Available copper and zinc in the soil profile The natural contents of available Cu extracted by ethylenediamine tetraacetic acid (EDTA) (CuEDTA) from the soil of the control treatment were 3.7 mg kg-1 in the 0-2.5, 2.5-5.0 and 5.0-10 cm layers, and 3.0 mg kg-1 in the 10-15 cm layer (Table 3)
In the PS90, PS180, DL90 and DL180 treatments, the greatest CuEDTA and Zn extracted by EDTA (ZnEDTA) contents were observed in the surface layer, 0-2.5 cm

Summary

Introduction

Pig slurry, generated from washing out the stalls with water, and pig deep litter, a residue from raising pigs on a layer of organic material, normally consisting of wood chips or straw from crops, has been used as a source of nutrients for crops in management systems such as no-tillage. Cu and Zn are retained by physicalchemical bonds, and their lability depends on the ligand, especially on the content of clay minerals, iron (Fe) oxides and hydroxides, aluminum (Al) and manganese (Mn), carbonates, and organic matter (McBride, 1994; Bradl, 2004), and on the pH value of the soil (Bradl, 2004), cation exchange capacity (CTC) and the quality of organic matter These factors define Cu and Zn adsorption in the soil and are found in different fractions in the soil, since naturally they are adsorbed at different energy levels (Casali et al, 2008; Girotto et al, 2010). Frequent manure applications may increase the quantity of soluble and exchangeable Cu and Zn fractions in the soil, creating a risk of potential toxicity for plants, and of potential water contamination, by transfer in runoff on the soil surface and leaching through the profile (Ceretta et al, 2010)

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