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Extraction and characterization of humic acid from low-rank coal mined reserves in South Sumatra and its application on red chili (Capsicum annuum L.) in fertilizer exhausted soil

Journal of Degraded and Mining Lands Management · Vol. 12 No. 4 (2025) · pp. 8065–8081

DOI
10.15243/jdmlm.2025.124.8065
ISSN
2502-2458, 2339-076X
Published
2025-07-01
Publisher
Brawijaya University
Language
eng
License
creativecommons.org/licenses/by-nc/4.0

Abstract

Intensive use of inorganic fertilizers has led to soil degradation, decreased productivity, and increased greenhouse gas emissions. Humic acid (HA) offers a sustainable solution by improving soil health and nutrient uptake while reducing dependence on chemical inputs. However, commercial HA from leonardite is expensive and rarely available in Indonesia. This study aimed to develop a high-quality and cost-effective HA product from low-rank coal (LRC) mined in South Sumatra. Given LRC’s low calorific value and high organic content, it presents an underutilized but promising HA source. A descriptive quantitative approach was used, starting with LRC selection and modified extraction to obtain HA. Laboratory-scale characterization revealed that locally sourced HA shares many functional groups with commercial leonardite-based HA. Hydrofluoric acid pretreatment significantly increased HA yield from 26.3% to 44%. A field trial was conducted on degraded soil overused with inorganic fertilizers, using a completely randomized block design with five treatments and five replications. Red chili (Capsicum annuum L.) was selected because of its high economic value. Data were analyzed using ANOVA at a significance level of 5%. The results showed that the combination of HA derived from LRC with low phosphate fertilizer (150 kg ha-1 SP-36 + 27 kg ha-1 HA) significantly increased plant height, fruit yield, and soil P availability, resulting in a yield of more than 28 t ha-1. These findings demonstrate the potential of LRC as a sustainable HA source to restore degraded soils and increase crop productivity in Indonesia.

Keywords

Collaboration network of the authors

40 authors · 198 co-authorship links · showing the 40 most connected

Hover or tap a name to highlight its co-authors. Double-click to open the author's page.

  • Al Baha University
  • Jenderal Soedirman University
  • Affiliation unknown
  • Different organisations
  • Same organisation
  • Affiliation unknown
  • Thicker line = more joint articles · bigger circle = more articles
Show as table
Co-authorOrganisationJoint articles
Mieke Rochimi SetiawatiAffiliation unknown10
Betty Natalie FitriatinAffiliation unknown9
Oviyanti MulyaniAffiliation unknown9
Muhamad Rahman DjuansahAffiliation unknown8
Pujawati SuryatmanaAffiliation unknown6
Benny JoyAffiliation unknown4
Agung KaruniawanAffiliation unknown4
Stefina Liana SariAffiliation unknown3
Rhazista NoviardiAffiliation unknown3
Abraham SuriadikusumahAffiliation unknown2
Rahmat BudiartoAl Baha University2
Saefur RohmanAffiliation unknown2
Tarra Martiana DewiAffiliation unknown2
Tualar SimarmataAffiliation unknown2
Baiq Azizah HaryantiniAffiliation unknown1
Yosef SitumorangAffiliation unknown1
Andriana KartikawatiAffiliation unknown1
Agus SusantoAffiliation unknown1
Wawan SutariAffiliation unknown1
Budy FrasetyaAffiliation unknown1
Puji LestariJenderal Soedirman University1
Purnomo PurnomoAffiliation unknown1
Solikhin SolikhinAffiliation unknown1
Lestari WibowoAffiliation unknown1
Agus M. HaririAffiliation unknown1
F.X. SusiloAffiliation unknown1
Yuyun FitrianaAffiliation unknown1
Hamim SudarsonoAffiliation unknown1
I Gede SwibawaAffiliation unknown1
Radix SuharjoAffiliation unknown1
Selvi HelinaAffiliation unknown1
Nur Rakhman Syaiful AkhdarAffiliation unknown1
Fatnuri FatnuriAffiliation unknown1
Made WiradikaAffiliation unknown1
Reginawanti HindersahAffiliation unknown1
Vera Oktavia SubarjaAffiliation unknown1

Affiliations come from OpenAlex; journal OAI-PMH metadata carries none. Authors without an OpenAlex ID are matched by name, which can merge or split people.

Metadata source: OAI-PMH (metadata jurnal) http://jdmlm.ub.ac.id/index.php/jdmlm/oai, first harvested 9 Nov 2026, last seen 9 Nov 2026.
Original metadata (oai_dc) 
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	<dc:title xml:lang="en-US">Extraction and characterization of humic acid from low-rank coal mined reserves in South Sumatra and its application on red chili (Capsicum annuum L.) in fertilizer exhausted soil</dc:title>
	<dc:creator>Hermawan, Mega Kartika</dc:creator>
	<dc:creator>Sofyan, Emma Trinurani</dc:creator>
	<dc:creator>Sudirja, Rija</dc:creator>
	<dc:creator>Nurbaity, Anne</dc:creator>
	<dc:subject xml:lang="en-US">FTIR analysis</dc:subject>
	<dc:subject xml:lang="en-US">HF treatment</dc:subject>
	<dc:subject xml:lang="en-US">humic acid extraction</dc:subject>
	<dc:subject xml:lang="en-US">low-rank coal </dc:subject>
	<dc:description xml:lang="en-US">Intensive use of inorganic fertilizers has led to soil degradation, decreased productivity, and increased greenhouse gas emissions. Humic acid (HA) offers a sustainable solution by improving soil health and nutrient uptake while reducing dependence on chemical inputs. However, commercial HA from leonardite is expensive and rarely available in Indonesia. This study aimed to develop a high-quality and cost-effective HA product from low-rank coal (LRC) mined in South Sumatra. Given LRC’s low calorific value and high organic content, it presents an underutilized but promising HA source. A descriptive quantitative approach was used, starting with LRC selection and modified extraction to obtain HA. Laboratory-scale characterization revealed that locally sourced HA shares many functional groups with commercial leonardite-based HA. Hydrofluoric acid pretreatment significantly increased HA yield from 26.3% to 44%. A field trial was conducted on degraded soil overused with inorganic fertilizers, using a completely randomized block design with five treatments and five replications. Red chili (Capsicum annuum L.) was selected because of its high economic value. Data were analyzed using ANOVA at a significance level of 5%. The results showed that the combination of HA derived from LRC with low phosphate fertilizer (150 kg ha-1 SP-36 + 27 kg ha-1 HA) significantly increased plant height, fruit yield, and soil P availability, resulting in a yield of more than 28 t ha-1. These findings demonstrate the potential of LRC as a sustainable HA source to restore degraded soils and increase crop productivity in Indonesia.</dc:description>
	<dc:publisher xml:lang="en-US">Brawijaya University</dc:publisher>
	<dc:date>2025-07-01</dc:date>
	<dc:type>info:eu-repo/semantics/article</dc:type>
	<dc:type>info:eu-repo/semantics/publishedVersion</dc:type>
	<dc:format>application/pdf</dc:format>
	<dc:identifier>https://jdmlm.ub.ac.id/index.php/jdmlm/article/view/17130</dc:identifier>
	<dc:identifier>10.15243/jdmlm.2025.124.8065</dc:identifier>
	<dc:source xml:lang="en-US">Journal of Degraded and Mining Lands Management; Vol. 12 No. 4 (2025); 8065-8081</dc:source>
	<dc:source>2502-2458</dc:source>
	<dc:source>2339-076X</dc:source>
	<dc:source>10.15243/jdmlm.2025.124</dc:source>
	<dc:language>eng</dc:language>
	<dc:relation>https://jdmlm.ub.ac.id/index.php/jdmlm/article/view/17130/1575</dc:relation>
	<dc:rights xml:lang="en-US">Copyright (c) 2025 Journal of Degraded and Mining Lands Management</dc:rights>
	<dc:rights xml:lang="en-US">https://creativecommons.org/licenses/by-nc/4.0</dc:rights>
</oai_dc:dc>