Prediction Models for Bioavailability of Mn, Cu, Zn, Ni and Pb in Soils of Republic of Serbia

Zoran Dinić,Radmila Pivić,Jelena Maksimović,Aleksandra Stanojković-Sebić

doi:10.3390/agronomy9120856

Abstract

The bioavailability of trace elements (TEs) is one of the major factors for successful plant production and environmental protection. The aim of this study was to determine the extent to which TEs are bioavailable and which of the basic soil parameters affect bioavailability. The survey included agricultural soil samples taken from 240 locations on the territory of the Republic of Serbia, where the soil analytics were carried out. On the basis of the analyzed data the prediction models were derived based on the Freundlich model, showing the dependence between trace elements (TEs) extracted using the DTPA buffer solution in relation to the trace elements extracted using an aqua regia, the organic matter content (SOM), the clay fractions content, and soil pH. On one part of the samples, the prediction models were separated on the basis of a suspension for determining the pH in H2O and 1M KCl. The model was applied for the following TEs: Mn, Ni, Pb, Zn, and Cu. The content of the pseudo total forms of TEs statistically significantly influenced the bioavailability of TEs in all prediction models for all studied elements. The pH value statistically significantly affected the bioavailability of Ni, Mn, Pb, and Cu also in all prediction models. The impact of SOM and clay varied depending on the model and TEs. Multiple linear regression showed that the prediction models for TE Cu (R2 = 0.763–0.848) were the most reliable and that the bioavailability of Cu was significantly influenced by all the studied soil parameters except clay. Reliable results were also shown by the prediction models for TE Pb, but the values of the determination coefficient and investigated parameters that influenced the bioavailability varied depending on the model. The derived models for TE Mn, Zn, and Ni were less reliable (R2 is approximately 50% or less), and the effect of the tested parameters on bioavailability varied depending on the model and TEs.

Highlights

Soil contains the main source of trace elements for plants [1]
Multiple linear regression showed that the prediction models for trace elements (TEs) Cu (R2 = 0.763–0.848) were the most reliable and that the bioavailability of Cu was significantly influenced by all the studied soil parameters except clay
Due to the importance of determining TEs extracted with DTPA buffer solution—available forms (TEDTPA) quantities and not having a complete prediction model that will include the most important soil parameters as factors affecting the mobility of TEs and pseudo total TEs forms (TEAR ), we propose to test the following prediction model: log (TEDTPA ) = A + b*pH + c*log(SOM) + d*log(Clay) + e*log(TEAR )

Summary

Introduction

Soil contains the main source of trace elements (micronutrients and non-essential elements) for plants [1]. There are two main transfer pathways that are significant for the evaluation of trace elements (TEs) risk in relation to living organisms: the soil-plant pathway, such as fodder and food crop, which introduces TEs into the food chain, and/or phytotoxicity and direct uptake through ingesting or inhalation by humans and animals [2]. Before the TEs become bioavailable to plants and other biota soil, they have to be mobile [3]. Plants are known to have mechanisms that regulate the uptake of TEs under conditions of deficiency or excess in soil. As the mechanisms by which the exclusion of TEs in excess are much weaker than those in deficit, the excess of TEs presents greater stress for the plant [1].

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Conclusion