Evaluation of Mehlich-3 multi-extractant for the determination of exchangeable bases and essential micronutrients in the Zimbabwe sugar industry soils · Electronic Theses and Dissertations

Author

Siyakisa, Fascinate M.

Title

Evaluation of Mehlich-3 multi-extractant for the determination of exchangeable bases and essential micronutrients in the Zimbabwe sugar industry soils

Abstract

The analysis of soil using single element extractants not only makes the analytical process long and expensive but also reduces the efficiency which comes with modern laboratory automation. This study was carried out to evaluate Mehlich-3 as a multi-element extractant for possible use in the determination of both soil exchangeable bases (calcium, magnesium, potassium, and sodium) and essential micronutrients (copper, iron, manganese, and zinc) in the Zimbabwe Sugar Industry soils. A total of 140 soil samples were collected across the Zimbabwe Sugar Industry covering Hippo valley, Triangle, Mkwasine, Mwenezana, and Zimbabwe Sugar Association Experiment Station. The soils were characterized for pH, texture, electrical conductivity, and organic matter. Exchangeable bases and micronutrients were extracted using conventional ammonium acetate and ethylenediaminetetraacetate extractants respectively and also by Mehlich-3 multi-element extractant. The extracted elements were quantified using Atomic Absorption Spectrometer for conventional methods and an Inductively Coupled-Plasma Optical Emission Spectrometer for the Mehlich-3 method. The Mehlich-3 method was validated by analyzing for accuracy, repeatability, intermediate precision, reproducibility, and robustness. There was a strong agreement between ammonium acetate and Mehlich-3 extractants on calcium, magnesium, potassium and sodium with R2 values of 0.959, 0.934, 0.92,8 and 0.889 respectively. A fairly strong agreement was also observed between ethylenediaminetetraacetate and Mehlich-3 with R2 values of 0.802, 0.835, 0.790 and 0.840 for micronutrients copper, iron, manganese, and zinc respectively. The method proved to be both repeatable and reproducible with relative standard deviations ranging from 0.72 % to 9.13 %. The recovery studies for accessing method accuracy ranged from 93% to 99%. Mehlich-3 proved to be competent and appropriate for extraction of all exchangeable base cations and essential micronutrients in the Zimbabwe Sugar Industry soils.

Date

2022

Publisher

BUSE

Keywords

Soil analysis

Evaluation of Mehlich-3

Soils

Supervisor

Dr Muchanyereyi, N.