Assessment of micronutrient extractants from soils of Paraná, Brazil

Marcos Vinicius Mansano Sarto,Fábio Steiner,Maria Do Carmo Lana

doi:10.1590/s0100-06832011000600024

Marcos Vinicius Mansano Sarto, Fábio Steiner + Show 1 more

Open Access

https://doi.org/10.1590/s0100-06832011000600024

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Abstract

In Brazil, plant-available micronutrients in the soil can be determined by several chemical extractants, the most common of which are dilute acid and chelating solutions. The purpose of this study was to assess the extractants 0.1 mol L-1 HCl, Mehlich-1, Mehlich-3 and DTPA for analysis of the micronutrients Cu, Zn, Fe, and Mn in soils from the state of Paraná. In samples from 12 soils (0-20 cm layer), wheat was planted (Triticum aestivum), grown for 42 days after emergence, and then bean (Phaseolus vulgaris) for 38 days. At the end of each planting period, the soil was sampled again. All extractants tested to assess the availability of Cu, Zn, Fe, and Mn correlated with each other. The efficiency of the extractants HCl, Mehlich-3 and DTPA in assessing plant-available Cu was similar, unlike Mehlich-1, which proved less efficient. The extractants HCl, Mehlich-1 and Mehlich-3 were less efficient in estimating plant-available Zn and Fe, and the most indicated extractant is DTPA. The efficiency of the extractants HCl, Mehlich-1, Mehlich-3 and DTPA in assessing plant-available Mn in soils from Paraná was similar.

Highlights

Crop yields may be limited by micronutrient deficiency caused by the low natural fertility of some soils, considerable nutrient removal by harvests and excessive application of phosphate fertilizers and substances for correction of soil acidity, causing the insolubility of micronutrients in the soil (Bortolon & Gianello, 2009).Knowledge of micronutrient availability in the soil is fundamental for suitable fertilization recommendations, to avoid deficiency or toxicity problems
For the choice of a method for soil analysis, a positive correlation between the nutrient concentration determined by the method and the nutrient quantity taken up by plants is fundamental (Lopes & Abreu, 2000)
The Cu, Zn, Fe, and Mn contents extracted from the soil by Mehlich-1, the method adopted by laboratories in Paraná (PR), correlated significantly with the contents extracted by HCl 0.1 mol-1, Mehlich3 and DTPA (Table 2)

Summary

Introduction

Crop yields may be limited by micronutrient deficiency caused by the low natural fertility of some soils, considerable nutrient removal by harvests and excessive application of phosphate fertilizers and substances for correction of soil acidity, causing the insolubility of micronutrients in the soil (Bortolon & Gianello, 2009).Knowledge of micronutrient availability in the soil is fundamental for suitable fertilization recommendations, to avoid deficiency or toxicity problems. For the choice of a method for soil analysis, a positive correlation between the nutrient concentration determined by the method and the nutrient quantity taken up by plants is fundamental (Lopes & Abreu, 2000). Several methods for micronutrient assessment in soils are available, and many of the extractants in routine analyses are used for multiple elements, in general developed for other nutrients and used for determination of Cu, Zn, Fe, and Mn due to the operational ease in laboratories for routine soil testing. In Brazil, different chemical extractants are used to determine plant-available Cu, Zn, Fe, and Mn, with dilute acid solutions, e.g, 0.1 mol L-1 HCl (Wear & Sommer, 1948) and Mehlich-1 (0.05 mol L-1 HCl and 0.0125 mol L-1 H2SO4) (Mehlich, 1953), and the chelates, such as DTPA and EDTA (Lindsay & Norvell, 1978). Chelating extractants in turn, have the capacity of reducing the activity of dissolved metals., resulting in release of more soluble compounds in buffered pH (Motta et al, 2007)

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