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Volume 52, Issue 3 p. 610-629
TECHNICAL REPORT

Effect of olive-processing technology on the utilization of olive mill pomace as a soil amendment

Marko Černe

Marko Černe

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Conceptualization, Data curation, Methodology, Writing - original draft

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Igor Palčić

Igor Palčić

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Conceptualization, Methodology, Project administration

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Nikola Major

Nikola Major

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Data curation

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Igor Pasković

Igor Pasković

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Conceptualization, Project administration

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Josipa Perković

Josipa Perković

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Methodology

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Zoran Užila

Zoran Užila

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Methodology

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Marina Lukić

Marina Lukić

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Methodology

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Marija Romić

Marija Romić

Faculty of Agriculture, University of Zagreb, Zagreb, Croatia

Contribution: Methodology

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Tea Zubin Ferri

Tea Zubin Ferri

ArcheoLab, Pula, Croatia

Contribution: Methodology

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Smiljana Goreta Ban

Smiljana Goreta Ban

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Contribution: Conceptualization, Writing - original draft

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Aleš Lapanje

Aleš Lapanje

Department of Environmental Sciences and Center for Electron Microscopy and Microanalysis (CEMM), Jožef Stefan Institute, Ljubljana, Slovenia

Contribution: Writing - original draft

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Jitka Hreščak

Jitka Hreščak

Department of Environmental Sciences and Center for Electron Microscopy and Microanalysis (CEMM), Jožef Stefan Institute, Ljubljana, Slovenia

Contribution: Methodology

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David John Heath

David John Heath

Department of Environmental Sciences and Center for Electron Microscopy and Microanalysis (CEMM), Jožef Stefan Institute, Ljubljana, Slovenia

Contribution: Writing - review & editing

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Dean Ban

Corresponding Author

Dean Ban

Department of Agriculture and Nutrition, Institute of Agriculture and Tourism, Poreč, Croatia

Correspondence

Dean Ban, Institute of Agriculture and Tourism, Karla Huguesa 8, 52440 Poreč, Croatia.

Email: [email protected]

Contribution: Project administration, Writing - review & editing

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First published: 14 February 2023
Citations: 1

Assigned to Associate Editor Rebecca Abney.

Abstract

In the Mediterranean basin, the treatment and disposal of olive mill pomace (OMP) remain a salient environmental issue for the olive oil-producing industry. This study assesses the effects of olive-processing technology (three-phase and two-phase systems) on the potential use of OMP as a soil amendment. Samples from 12 Croatian olive mills were analyzed for their total phenolic content (TPC), residual oil fraction, and elemental concentration. The samples were profiled using Fourier transform infrared spectroscopy (FT-IR) and structurally characterized using scanning electron microscopy-energy-dispersive X-ray spectroscopy (EDS). Compared to three-phase samples, two-phase OMP was more acidic (pH 4.5 vs. 5.0), with a higher TPC (3835 vs. 1576 mg/kg fresh weight), oil content (11.7% vs. 7.5% d.w., where d.w. is dry weight), electrical conductivity (EC, 5.1 vs. 3.0 mS/cm), and levels of calcium (Ca, 1.34 vs. 1.20 g/kg d.w.) and copper (Cu, 10.4 vs. 7.0 mg/kg d.w.). Similar values of carbon/nitrogen (C/N; 61 vs. 72), N (10 vs. 8.1 g/kg d.w.), phosphorus (1040 vs. 691 mg/kg d.w.), and potassium (K, 13.7 vs. 8.1 g/kg d.w.) were observed. The amounts of chromium, copper, nickel, and zinc were below EC limits in both cases. The EDS mapping revealed that Ca was concentrated at sharp-edged OMP particles while K was evenly distributed, suggesting that pelletized OMP compost is preferable for amending soil to obtain a homogeneous distribution of nutrients. It was also possible to distinguish between OMPs based on oil and lignin absorption bands in their FT-IR spectra. According to the obtained results, composting is recommended for both types of OMP to produce a safe product for amendment purposes.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflict of interest.

DATA AVAILABILITY STATEMENT

All data generated or analyzed during this study are included in this published article.