Abstract

GANNINI-KURINA, Franca et al. Conversion models of FE, MN, CU and ZN concentrations between MEHLICH-3 and DTPA-TEA extraction methods in soils of Córdoba. Cienc. suelo [online]. 2021, vol.39, n.2, pp.1-15. ISSN 1850-2067.

The aim of this work was to study the correlation between two widely used extraction solutions in soil nutrients determination. The compared solutions were Mehlich-3 and diethylenetriaminepentaacetic acid-triethanolamine, DTPA-TEA. The concentration of Fe, Mn, Cu and Zn were obtained using these solutions and determined by atomic absorption spectrophotometry in 93 soils samples of the first 15 cm of depth distributed throughout the territory of Córdoba. For the four elements Mehlich-3 showed higher concentration compared to concentration obtained with DTPA-TEA. However, the concentrations obtained by both methods were positive correlated among soils. For each micronutrient, we fitted a regression model of the concentration obtained by DTPA-TEA as a function of the concentration obtained by Mehlich-3 plus a group of soil properties. We found that the differences in concentrations between extractants depended on the soil abundance of the element and intrinsic characteristics of the soil matrix. The variables pH and sand content described the interaction between soil and extraction solution and were incorporated in the models used to convert concentration obtained by Mehlich-3 to DTPA-TEA. The fitted regression models had good statistical performance. Better fits were obtained for Fe (R2 = 0.81) and Mn (R2 = 0.73) compared with those obtained for Cu (R2 = 0.67) and Zn (R2 = 0.66). The proposed models make possible the conversion of results obtained with one method to another, facilitating studies of micronutrient concentrations where determinations come from different sources.

Keywords : Soil nutrients; Extractant; Measurement agreement; Regression models.

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