DOI: https://doi.org/10.56669/FIXF7720
ABSTRACT
The implementation of sustainable agriculture in Indonesia faces various challenges, one of which is the presence of heavy metal pollution on agricultural land. It directly threatens soil health, crop productivity, and food safety. This review explores the potential of biofertilizers as an environmentally friendly biological approach to mitigate heavy metal stress in plants. Functional microorganisms such as nitrogen-fixing bacteria (Rhizobium), phosphate-solubilizing bacteria (Bacillus, Pseudomonas), Vesicular Arbuscular Mycorrhiza (VAM), and siderophore-producing bacteria play a crucial role in this process. These microorganisms use various mechanisms to overcome heavy metal stress, including biosorption, bioaccumulation, and bioprecipitation, which mitigate rather than remove heavy metals from the soil by decreasing their bioavailability and toxicity. Their effects may therefore require periodic application to sustain bioremediation performance. In addition, biofertilizers can enhance plant resilience to abiotic stress by producing phytohormones and inducing systemic resistance. Case studies across Indonesia demonstrate that the application of biofertilizers has successfully reduced heavy metal accumulation in crops such as corn and rice on contaminated land, resulting in improved plant growth and biomass. However, the widespread adoption of biofertilizers faces obstacles, including low farmer literacy, variability in product quality, and challenges in regulatory implementation. Strengthening technical, social, and policy aspects is necessary so that biofertilizers can be widely and effectively applied to overcome heavy metal pollution issues and support sustainable agricultural practices in Indonesia.
Keywords: bioremediation, heavy metal pollution, microorganisms, sustainable agriculture
INTRODUCTION
Background
Sustainable agriculture plays a vital role in responding to global challenges to achieve a balance between ecosystem sustainability and food security, along with population growth. The world's population is expected to reach more than 10 billion by 2055, placing increased demands in the agricultural sector to meet future food needs. A sustainable agricultural system considers ecosystem, economic, and social aspects that are sustainable into the future by holding ecological, socio-economic, technical, and political principles (Dewi et al., 2024; Raidar et al., 2023). This concept emphasizes the wise management of natural resources to maintain agricultural productivity without damaging the ecosystem. Li and Yan (2020) mentioned that conventional farming systems with intensive land use and reliance on chemical fertilizers and pesticides are now considered irrelevant for maintaining because they can cause land degradation, reducing its productivity. This has led to the need to strengthen environmentally friendly agricultural practices to mitigate the negative impacts of intensive cultivation activities, which often overlook ecological aspects.
The implementation of sustainable agriculture in Indonesia faces various challenges, one of which is heavy metal pollution on agricultural land. Many areas in Indonesia have experienced heavy metal contamination, as seen in Wonosobo Regency, Central Java. Research by Dewi et al. (2023) showed that soil samples were contaminated with heavy metals of lead (Pb), cobalt (Co), nickel (Ni), chromium (Cr), arsenic (Ar), and cadmium (Cd). Soils polluted by heavy metals experience changes in soil properties such as a decrease in pH to a reduction in soil biota activity. Changes in the physical, chemical, and biological properties of soil on agricultural land contaminated by heavy metals can disrupt plant physiological processes, reduce yield production, and cause heavy metal accumulation in plant tissues. This threatens the health of humans who consume them. Heavy metals are not easily degraded, so they can accumulate in human body tissues and cause organ damage, metabolic disorders, and chronic diseases such as cancer (Sarma et al., 2024).
One of the efforts to overcome the problem of heavy metal pollution in achieving sustainable agriculture is through a biological approach, utilizing biofertilizers as bioremediation agents. The mechanism of bioremediation involves the absorption, binding, or transformation of toxic compounds into less toxic forms (Calvina et al., 2024). Biofertilizers not only provide additional nutrient supply for plants but are also able to reduce the negative impact of heavy metal pollution on agricultural land. The application of microorganisms as bioremediation agents through biofertilizers reduces the accumulation of heavy metals in plant tissues. In addition, some types of microorganisms are also able to increase plant resistance to abiotic stress by producing antioxidant compounds so that plants can grow well even on land polluted with heavy metals (Haroun et al., 2023; Kurnia 2023). Therefore, research on the use of biofertilizers in mitigating heavy metal stress in plants in Indonesia is necessary.
TYPES OF BIOFERTILIZERS THAT ARE POTENTIAL IN ADDRESSING HEAVY METALS
Biofertilizers are one of the environmentally friendly solutions that can be used to reduce the impact of heavy metals on plants. One type that has been widely studied is nitrogen-fixing bacteria, such as those from the genus Rhizobium and Bradyrhizobium. Sari and Prayudyaningsih (2020) stated that the two genera have potential as bioremediation because they can fix free nitrogen and produce plant growth hormones such as IAA (Indole Acetic Acid) to support plant growth. Rhizobium is also known to play a role in the metal bioremediation process because it has a metallothionein enzyme that can bind metals (Ambarsari and Qisthi, 2017). Other potential species include phosphate-solubilizing bacteria, such as those belonging to the Bacillus and Pseudomonas genera. Bacillus species can be bioremediation agents through enzymatic mechanisms that can reduce the toxicity of heavy metals to plants. Meanwhile, Pseudomonas can bind and accumulate metals in its cells so as to reduce the availability of metals in the soil (Aznur et al., 2022). Both bacteria can also dissolve phosphate compounds bound by heavy metals so that phosphorus (P) remains available to plants. The remediation mechanism by maintaining the availability of P in plants is also owned by Vesicular Arbuscular Mycorrhiza (VAM). Faiza et al. (2013) mentioned that heavy metal-polluted soils tend to have low P-available levels because P elements are bound by metals such as Al and Fe. VAM can degrade these bonds to increase the level of P that plant roots can absorb in heavy metal polluted soil conditions. VAMs that form symbiotic relationships with roots can also help retain heavy metals in the roots so that they do not accumulate in the upper part of the plant (Indraningsih et al., 2016).
Some bacteria, such as Rhizobium and Bacillus, are known not only as nitrogen fixers and phosphate solvents but are also capable of producing siderophore compounds that help bind heavy metals in the soil. This ability is also possessed by other bacteria that specifically produce siderophores as the main mechanism to reduce heavy metal availability to plants. Research by Nurikhsanti et al., (2024) showed that bacterial isolates from peanut rhizosphere produce catecholate-type siderophores that effectively bind heavy metals and suppress pathogen growth. Organic compound-degrading bacteria, such as those from the genus Bacillus, Pseudomonas, and Micrococcus, can also be used in heavy metal remediation due to their ability to degrade complex organic compounds into simpler compounds to obtain energy (Anggriany et al., 2018). These bacteria can break down hydrocarbon compounds that form stable bonds with heavy metals. This activity can help release metals from their binding organic compounds, thereby facilitating the process by which bacterial cells bind metal ions (Angraeni and Triajie, 2021).
MECHANISM OF BIOFERTILIZER IN OVERCOMING HEAVY METAL STRESS
Microorganisms in heavy biofertilizers have various biochemical mechanisms to reduce the toxicity of metals to plants. One of the main mechanisms of microorganisms in bioremediation is biosorption, as carried out by Pseudomonas aeruginosa bacteria. Biosorption is a passive process that involves the adsorption of metal ions by the surface of microorganism cells rich in functional groups to bind them to the cell extracellularly. Bacterial cells have negative charges located on their cell walls, such as carboxyl (COO-) and hydroxyl (OH-), so they will interact with metal ions that are usually positively charged (Anggraeni and Triajie 2021; Setiawan et al., 2019). Microorganisms also accumulate metals intracellularly through bioaccumulation mechanisms. This ability actively transports metals from the environment into bacterial cells, as shown by Streptomyces sp. (Lestari et al., 2022). Bioremediation mechanisms are also carried out by microorganisms through bioprecipitation, as performed by bacteria from Bacillus cereus. This process utilizes the metabolic activity of microorganisms to actively precipitate dissolved metal ions into stable precipitate compounds with low solubility (Nuriman et al., 2025; Octavia et al., 2018). Precipitation is one of the mechanisms carried out by some bacteria to reduce the concentration of free metals into insoluble complexes to reduce their toxicity and bioavailability (Rohmayani et al., 2024). These microbial processes mitigate heavy metal toxicity without permanently removing the metals from the soil, as they are immobilized in less soluble or less bioavailable fractions rather than eliminated from the environment.
Bioavailability is the availability of metals that can be absorbed by plants so that they can cause toxic effects on plants. Microorganisms carry out regulation of bioavailability through the process of biosorption, chelation, precipitation, and the formation of organic complexes that move metals from readily available fractions to fractions that are more stable and difficult for plants to absorb (Siaka et al., 2020; Rohmayani et al., 2024). This mechanism can suppress the accumulation of heavy metals in plant tissues, thereby reducing physiological disorders in plants. In addition to improving the polluted environment, microorganisms in biofertilizers can also induce plant resistance to abiotic stresses such as drought and heavy metals. Some examples of microorganisms that can increase plant resistance to abiotic stress are VAM and PGPR (Plant Growth-Promoting Rhizobacteria). VAM symbiosis can expand the root absorption area and improve the absorption of essential nutrients that play a role in maintaining ion balance and enzyme function in conditions exposed to heavy metals. VAM also triggers the accumulation of osmoprotectant compounds such as proline, soluble sugar, and glycine betaine, and increases antioxidant activity that plays a role in suppressing oxidative stress due to heavy metal exposure (Ilwati et al., 2024). Meanwhile, PGPR can produce phytohormones (auxins, gibberellins, cytokinins) and induce systemic resistance compounds that can activate defense genes in plants, strengthen cell walls, and increase the production of detoxification enzymes so as to increase plant tolerance to heavy metal stress (Riseh et al., 2023).
CASE STUDY OF BIOFERTILIZER UTILIZATION IN INDONESIA
Heavy metal pollution is a challenge in agricultural land management in Indonesia. Various studies conducted found that soils in various regions in Indonesia have contained heavy metals such as arsenic (Ar), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), nickel (Ni), copper (Cu), and lead (Pb) (Dewi et al., 2023; Hindersah et al., 2018; Panjaitan and Sidauruk 2023). Dewi et al., (2023) mentioned that 312 soil samples from agricultural land in Wonosobo Regency, Central Java contained heavy metals with the highest to lowest content of Pb > Co > Ni > Cr > As > Cd which each had a concentration of 11.00 + 2.80 mg kg-1; 10.83 + 3.19 mg kg-1; 6.04 + 2.86 mg kg-1; 3.56 + 2.31 mg kg-1; 2.02 + 1.17 mg kg-1; and 1.23 + 0.43 mg kg-1. The concentration of heavy metals based on the study is still considered normal in the soil naturally due to the weathering activity of soil-forming rocks. However, fertilization practices can increase the content of heavy metals Pb, Cd, and Ni in the soil. Intensive fertilization activities on agricultural land continuously risk exceeding normal limits in soil for heavy metal pollution (Zhang et al. 2020).
Many efforts to control heavy metal pollution on agricultural land have been carried out, one of which is by using biological fertilizers. Indraningsih et al., (2016) stated that inoculation of Arbuscular Mycorrhizal Fungi (AMF) was able to increase the growth of corn plants in tailings soil of former gold mines from Sekotong District, West Lombok, West Nusa Tenggara which was contaminated with Hg with an initial level of 4.37 ppm. Application of AMF together with manure and dolomite produced plants with greater height, number of leaves, and biomass than the treatment without mycorrhiza. Most of the Hg absorbed by plants accumulated in the roots, suggesting that FMA plays a role in phytostabilization mechanisms that help retain heavy metals in the root zone. Although the total mercury content in soil remained relatively constant, the inoculation helped decrease the bioavailable fraction, leading to reduced translocation of metals to the upper plant parts. A similar case also occurred in the Gunung Botak area, Buru Island, Maluku. Some tailings from gold mining were deposited on agricultural land so that mercury (Hg) levels in the land were <5 mg/kg (Hindersah et al., 2018). Research by Hindersah et al. (2021) using soil samples from the site showed that the soil had a very acidic nature with initial Hg levels of 1.64 mg/kg. Biological agents from Azotobacter bacteria and cow dung compost application were used to determine their potential in reducing Hg content and its impact on corn plant growth. The results showed that the combination of 30 g/polybag compost and Azotobacter chroococcum inoculation or Azotobacter consortium was most effective in reducing Hg levels in the soil to the range of 0.92-0.98 mg/kg. The treated corn plants were able to absorb Hg up to 1.34 mg/kg, which is still classified as moderate and does not interfere with plant metabolism. Corn plant growth and biomass tended to increase in the Azotobacter inoculation treatment.
The effectiveness of biofertilizers in overcoming heavy metal pollution was also observed in rice plants. Ubaidillah et al. (2023) tested a consortium of rhizosphere bacteria consisting of Rhizobium sp., Azotobacter sp., Azospirillum sp., Pseudomonas sp., and Bacillus sp. on Pb- contaminated rice fields. The application of a bacterial consortium can reduce oxidative stress in plants due to heavy metals, as indicated by a decrease in MDA (Malondialdehyde) and ROS (Reactive Oxygen Species) levels. The results showed that Pb content in rice plant tissues decreased by 45% compared to the control, accompanied by an increase in root length by 41%, fresh weight by 32%, dry weight by 26%, and chlorophyll content by 25%. These results are reinforced by the findings of Panjaitan and Sidauruk (2023), who also used a consortium of bacteria on mustard plants in soil polluted with heavy metals Pb and Cu. The bacterial consortium used, namely Corynebacterium glutamicum and Lactobacillus sp., was able to reduce the concentration of heavy metals in the soil through the mechanism of rhizodegradation. The results showed that increasing the dose of bacterial inoculation and biochar significantly reduced the concentration of Pb and Cu in soil and plant tissues. The average reduction of Pb in soil and plants with bacterial treatment was 1.28% and 0.29%. Meanwhile, the average decrease in Cu content in soil and plants with bacterial treatment was 1.03% and 0.17%. The reduction of heavy metal concentration was followed by an increase in plant growth characterized by the number of leaves and higher plant height and greater plant wet weight in the combination treatment of biochar 20 g/plant and bacteria 10 g/plant. Overall, these studies show that biofertilizers alleviate heavy metal stress primarily through bioavailability reduction and plant tolerance rather than by eliminating metals from the soil.
FACTORS AFFECTING THE EFFECTIVENESS OF BIOFERTILIZERS
The effectiveness of biofertilizers in overcoming heavy metal stress can be influenced by the interaction between the type of microorganisms used, the type of plants planted, the environmental conditions, as well as the frequency and continuity of biofertilizer application. Soils with neutral to slightly acidic pH are optimal conditions for microorganism growth because enzymes can work well although some strains can survive at extreme pH (3.5-12.5) (Kumar et al., 2019). Other soil characteristics, such as texture and organic matter content, can also affect the effectiveness of biofertilizers. High organic matter content can improve soil structure, increase cation exchange capacity, and provide energy sources for microorganisms such as Pseudomonas, Bacillus, and Acinetobacter. These factors also require support from environmental conditions, such as suitable temperature and humidity, to maintain the optimal metabolism of microorganisms (Susilowati et al., 2024). In polluted soils, heavy metal concentrations that are too high can inhibit the enzyme function of microorganisms and plant growth, which can reduce the effectiveness of biofertilizers. However, multi-resistant bacteria such as Acinetobacter sp. IrC2 are able to survive high metal concentrations through the mechanism of accumulation and transformation of metals into less toxic forms. Microorganisms are specific to the elements that can be absorbed, so the type of microorganisms used in biofertilizers also determines the effectiveness of biofertilizers (Irawati et al., 2020; Sudaryono and Susanto, 2015). Plant species can also affect the effectiveness of biofertilizers through differences in root exudates that form specific microorganism communities in the rhizosphere. The presence of hyperaccumulator plants such as hanjuang (Cordyline fruicosa) and sunflower (Helianthus annuus) help reduce Pb, Cd, Cu, and Cr levels in the soil, thereby reducing toxic pressure on microorganisms and cultivated plants and increasing the effectiveness of biofertilizers (Widyasari et al., 2024). Moreover, since the population and activity of microorganisms tend to decline after harvest, the effectiveness of biofertilizers is also influenced by the frequency of their application. Periodic inoculation, typically once every planting cycle, helps sustain microbial performance and maintain the bioremediation potential in subsequent crops (Wang et al., 2025).
CHALLENGES AND BARRIERS IN THE UTILIZATION OF BIOFERTILIZERS IN INDONESIA
The use of biofertilizers in Indonesia faces various challenges and obstacles related to the level of knowledge, product quality, ecological suitability, and regulations. Farmers' level of literacy and confidence in the benefits and application techniques are often inadequate so that the adoption of this technology tends to be partial and inconsistent (Rafiudin et al., 2022; Irwandhi et al., 2024). The availability and quality of commercial biofertilizer products are not always uniform because the viability of microorganisms decreases during the formulation, storage, and distribution processes, thus reducing the performance of biofertilizer effectiveness when applied in the field (Fadiji et al., 2024; Santos et al., 2024). The efficacy of biofertilizers is also influenced by the adaptability of strains to local ecosystems, including soil types, microclimates, and types of cultivated crops, so the use of native strains and multilocation testing is needed to ensure consistency of performance from the laboratory to farmers' fields (Irwandhi et al., 2024; Fadiji et al., 2024). Regulatory tools such as Minister of Agriculture Regulation No. 01/PERMENTAN/SR.130/1/2019 and Minister of Agriculture Decree No. 261/KPTS/SR.310/M/4/2019 have established minimum technical specifications and registration procedures for biological fertilizers, but implementation is still constrained by limited testing facilities, weak quality control, and uncontrolled on-farm propagation practices (Kepmentan, 2019; Permentan, 2019; Santos et al., 2024).
ADVANTAGES OF BIOFERTILIZERS COMPARED TO CHEMICAL FERTILIZERS
Biofertilizers have several advantages over chemical fertilizers, especially in terms of sustainability and impact on the environment. Biofertilizers are an environmentally friendly alternative because they contain functional microorganisms that work naturally in improving the physical, chemical, and biological properties of soil without leaving harmful residues or pollutants, so that they can maintain long-term soil fertility (Putra et al., 2023). The application of biofertilizers can reduce dependence on chemical fertilizers, thereby reducing the risk of groundwater pollution and damage to soil structure due to excess urea. In addition, the presence of beneficial microorganisms such as Rhizobium, Azotobacter, and mycorrhiza in biofertilizers can improve soil health through nitrogen fixation, phosphate dissolution, increased potassium availability, decomposition of organic matter, and biological control of plant pests (Setiawati et al., 2016; Sriwahyuni and Parmila 2019). Biofertilizers improve plant health and indirectly reduce the use of chemical pesticides. Biofertilizers can increase plant resistance to pests and diseases through antagonistic mechanisms against pathogens and induction of systemic resistance in plants so that synthetic chemical inputs can be reduced (Ilwati et al., 2024; Istikorini et al., 2024).
CONCLUSIONS
Biofertilizers have great potential in overcoming heavy metal stress on agricultural land in Indonesia through the use of functional microorganisms such as Rhizobium, Bacillus, Pseudomonas, Vesicular Arbuscular Mycorrhiza (VAM), and siderophore-producing bacteria. These microorganisms can reduce heavy metal bioavailability through biosorption, bioaccumulation, bioprecipitation, chelation, degradation of organic compounds, and induce plant resistance to abiotic stress. Environmental factors influence the effectiveness of biofertilizers, the type of microorganisms used, and the type of plants cultivated. Biofertilizers have advantages over chemical fertilizers in terms of sustainability and environmental impact. However, their use still faces obstacles in the form of low farmer literacy, variable product quality, limited strain adaptation to local conditions, and suboptimal regulatory implementation. Strengthening technical, social, and policy aspects needs to be done so that the use of biofertilizers can be widely and effectively applied in the field to overcome the problem of heavy metal stress in agricultural land. In addition, periodic application of biofertilizers is necessary to maintain their effectiveness in reducing heavy metal bioavailability and supporting plant health.
REFERENCES
Ambarsari H, Qisthi A. 2017. Remediasi merkuri (Hg) pada air limbah tambang emas rakyat dengan metode lahan basah buatan terpadu. Jurnal Air Indonesia 18(2):148-156.
Anggraeni A, Triajie H. 2021. Uji kemampuan bakteri (Pseudomonas aeruginosa) dalam proses biodegradasi pencemaran logam berat timbal (Pb), di Perairan Timur Kamal Kabupaten Bangkalan. Juvenil: Jurnal Ilmiah Kelautan dan Perikanan 2(3):176-185.
Anggriany PS, Jati AWN, Murwani LI. 2018. Pemanfaatan bakteri indigenus dalam reduksi logam berat Cu pada limbah cair proses etching Printed Circuit Board (PCB). Biota: Jurnal Ilmiah Ilmu-Ilmu Hayati 3(2):87-95.
Aznur BS, Nisa SK, Septriono WA. 2022. Agen biologis potensial untuk bioremediasi logam berat. Jurnal Maiyah 1(4):186-198.
Calvina AB, Ardiana AD, Azzahra CS, Santosa NR, Miladya NF, Anwar NZ, Isnaeni. 2024. Bioremediasi cemaran tanah menggunakan biostimulant. Camellia: Clinical, Pharmaceutical, Analytical and Pharmacy Community Journal 3(2):192-204.
Dewi SBL, Aulia RV, Laily DW. 2024. Implementasi pertanian berkelanjutan dengan memanfaatkan limbah pertanian menjadi pupuk organik cair di Desa Musir Lor Kabupaten Nganjuk. Jurnal Abdi Masyarakat Indonesia 4(4):1067-1076.
Dewi T, Handayani CO, Hidayah A, Sukarjo S. 2023. Sebaran konsentrasi logam berat di lahan pertanian Kabupaten Wonosobo. Jurnal Tanah dan Sumberdaya Lahan 10(2):515-521.
Fadiji AE, Xiong C, Egidi E, Singh BK. 2024. Formulation challenges associated with microbial biofertilizers in sustainable agriculture and paths forward. Journal of Sustainable Agriculture and Environment 3(3):1-18.
Faiza R, Rahayu YS, Yuliani. 2013. Identifikasi spora jamur Mikoriza Vesikular Arbuskular (MVA) pada tanah tercemar minyak bumi di Bojonegoro. LenteraBio: Berkala Ilmiah Biologi 2(1):7-11.
Haroun M, Xie S, Awadelkareem W, Wang J, Qian X. 2023. Influence of biofertilizer on heavy metal bioremediation and enzyme activities in the soil to revealing the potential for sustainable soil restoration. Scientific Reports 13(20684):1-13.
Hindersah R, Nurhabibah G, Harryanto R. 2021. Inokulasi Azotobacter dan aplikasi kompos untuk bioremediasi tailing terkontaminasi merkuri. Jurnal Teknologi Mineral dan Batubara 17(1):39-46.
Hindersah R, Risamasu R, Kalay AM, Dewi T, Makatita I. 2018. Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine in Buru Island, Maluku. Journal of Degraded and Mining Lands Management 5(2):1027–1034.
Ilwati U, Sudharmawan AK, Sudantha IM. 2024. the effect of mycorrhiza on sorghum plants in dryland areas. Jurnal Biologi Tropis 24(2b):294-302.
Indraningsih B, Utomo WH, Handayanto E. 2016. Effects of mycorrhizae on phytoremediation of soil contaminated with small-scale gold mine tailings containing mercury. International Journal of Research in Agricultural Sciences 3(2):104-109.
Irawati W, Hasthosaputro A, Kusumawati L. 2020. Multiresistensi dan akumulasi Acinetobacter sp. IrC2 terhadap logam berat. Jurnal Biologi Papua 12(2):114-122.
Irwandhi I, Khumairah FH, Sofyan ET, Kamaluddin NN, Nurbaity A, Herdiyantoro D, Simarmata T. 2024. Current status and the significance of local wisdom biofertilizer in enhancing soil health and crop productivity for sustainable agriculture: a systematic literature review Kultivasi 23(3):287-298.
Istikorini Y, Firmansyah MA, Kurniawati F, Mubin N. 2024. Pelatihan pembuatan pupuk hayati di Desa Gondel, Kecamatan Kedungtuban, Kabupaten Blora, Jawa Tengah. Agrokreatif: Jurnal Ilmiah Pengabdian kepada Masyarakat 10(3):305-314.
[Kepmentan] Keputusan Menteri Pertanian Republik Indonesia Nomor 261/KPTS/SR.310/M/4/2019 Tentang Persyaratan Teknis Minimal Pupuk Organik, Pupuk Hayati, dan Pembenah Tanah. 2019.
Kumar A, Kumari M, Swarupa P. 2019. Characterization of pH dependent growth response of agriculturally important microbes for development of plant growth promoting bacterial consortium. Journal of Pure and Applied Microbiology 13(2):1053-1062.
Kurnia A. 2023. Identifikasi logam berat pada air kolong dan mikroba potensial untuk bioremediasi di lahan pasca penambangan timah. Jurnal Geominerba 8(1):36-43.
Lestari MD, Miranda M, Setiawati UN, Nukmal N, Setyaningrum E, Arifiyanto A, Aeny TN. 2022. Bioakumulasi dan aktivitas resistensi logam timbal (Pb) terhadap Streptomyces sp. strain I18. Jurnal Sumberdaya Alam dan Lingkungan 9(1):1-6.
Li Q, Yan J. 2020. Sustainable agriculture in the era of omics: knowledge-driven crop breeding. Genome Biology 21(154):1-5.
Nurikhsanti M, Zulkifli L, Rasmi DAC, Sedijani P. 2024. Antagonistic test of bacteria producing siderophore and protease enzymes from the rhizosfer of peanut plants on the growth of pathogenic fungus Colletotrichum gloeosporioides. Jurnal Biologi Tropis 24(1):100-108.
Nuriman M, Wibowo SS, Rezekikasari R, Agustine L, Setiawati T. 2025. Bio-reclamation evaluation of former gold mine land: pre-and post-reclamation soil management conditions. Jurnal Biologi Tropis 25(3):2457-2464.
Octavia B, Yuwono T, Taftazani A. 2018. Efek pelaparan dan akumulasi polifosfat terhadap biopresipitasi uranium pada Bacillus cereus A66. Biotropika: Journal of Tropical Biology 6(2):68-77.
Panjaitan E, Sidauruk L. 2023. Pemanfaatan biochar dan konsorsium bakteri pada remediasi tanah tercemar logam berat dan pengaruhnya terhadap hasil tanaman sawi (Brassica juncea L.). Agrotekma: Jurnal Agroteknologi dan Ilmu Pertanian 8(1):46-55.
[Permentan] Peraturan Menteri Pertanian Republik Indonesia Nomor 01 Tahun 2019 Tentang Pendaftaran Pupuk Organik, Pupuk Hayati, dan Pembenah Tanah. 2019.
Putra AP, Wicaksono LS, Gunawan SS, Putra AB, Prahesti IA, Ainiyah BQ, Nugraha DR, Basuki B. Pertanian organik: perbanyakan pupuk hayati ramah lingkungan demi upaya swasembada beras nasional. SELAPARANG: Jurnal Pengabdian Masyarakat Berkemajuan. 7(3):1849-1853.
Rafiudin RU, Siswoyo S, Maryani A. 2022. Tingkat adopsi penggunaan pupuk hayati pada budidaya padi sawah (Oryza sativa L.) di Kecamatan Bungursari Kota Tasikmalaya. SEPA: Jurnal Sosial Ekonomi Pertanian Dan Agribisnis 18(2):247-259.
Raidar U, Ramadhan F, Nufus NRK, Supriyatna MR, Pesema EA, Nabila Z, Safitri A. 2023. Penyuluhan pertanian pengendalian hama tikus dan pembuatan biosaka sebagai upaya mendukung sistem pertanian berkelanjutan di Pekon Banjarmasin. BUGUH: Jurnal Pengabdian Kepada Masyarakat 3(2):112-117.
Riseh RS, Vazvani MG, Hajabdollahi N, Thakur VK. 2023. Bioremediation of heavy metals by rhizobacteria. Applied Biochemistry and Biotechnology 195(8):4689-4711.
Rohmayani V, Romadhon N, Arimurti ARR. 2024. Identifikasi bakteri di mangrove Desa Sawohan Sidoarjo sebagai agen bioremediasi dari pencemaran logam berat. SAGO: Gizi dan Kesehatan 5(3A):733-745.
Santos F, Melkani S, Oliveira-Paiva C, Bini D, Pavuluri K, Gatiboni L, Mahmud A, Torres M, McLamore E, Bhadha JH. Biofertilizer use in the United States: definition, regulation, and prospects. Applied Microbiology and Biotechnology 108(511):1-16.
Sari R, Prayudyaningsih R. 2020. Isolasi dan potensi bakteri fiksasi nitrogen simbiotis dari bintil akar Falcataria moluccana (Miq.) Barneby & JW Grimes untuk mendukung reklamasi lahan bekas tambang nikel. Jurnal Penelitian Kehutanan Wallacea 9(2):111-120.
Sarma HH, Rajkumar A, Baro A, Das BC, Talukdar N. 2024. Impact of heavy metal contamination on soil and crop ecosystem with advanced techniques to mitigate them. Journal of Advances in Biology & Biotechnology 27(6):53-63.
Setiawan A, Basyiruddin F, Dermawan D. 2019. Biosorpsi logam berat Cu (II) menggunakan limbah Saccharomyces cereviseae. Jurnal Presipitasi: Media Komunikasi dan Pengembangan Teknik Lingkungan 16(1):29-35.
Setiawati MR, Sofyan ET, Mutaqin Z. 2016. Pengaruh pupuk hayati padat terhadap serapan N dan P tanaman, komponen hasil dan hasil padi sawah (Oryza sativa L.). Jurnal Agroekoteknologi 8(2):120-130.
Siaka IM, Rozin WA, Putra KGD. 2020. Spesiasi dan bioavailabilitas logam berat dalam sedimen Sungai Roomo Gresik. Jurnal Kimia 14(2):153-161.
Sriwahyuni P, Parmila P. 2019. Peran bioteknologi dalam pembuatan pupuk hayati. Agro Bali: Agricultural Journal 2(1):46–57
Sudaryono S, Susanto JP. 2015. Pengaruh pupuk hayati terhadap akumulasi timbal dari kompos sampah kota dalam jaringan tanaman padi. Jurnal Pangan 24(1):25-36.
Susilowati LE, Sukartono S, Akbar MF, Kusumo BH, Suriadi A, Leksono AS, Fahrudin F. 2024. Assessing the synergistic effects of inorganic, organic, and biofertilizers on rhizosphere properties and yield of maize. SAINS TANAH-Journal of Soil Science and Agroclimatology 21(1):104-116.
Ubaidillah M, Thamrin N, Cahyani FI, Fitriyah D. 2023. Bioremediation potential of rhizosphere bacterial consortium in lead (Pb) contaminated rice plants. Biodiversitas Journal of Biological Diversity 24(8):4566-4571.
Wang Z, Wang H, Qing H, Lin Q, Li J, Fu X, Kuramae EE. 2025. Periodic bioinoculations enhance soil aggregate stability through species-specific effects and interactions with the native microbiota. Geoderma 459(117345):1-10.
Widyasari NL, Rai IN, Dharma IGB, Mahendra MS. 2024. Study of controlling the content of Pb, Cu, Cd, and Cr in soils using hyperaccumulator plants. Journal of Degraded & Mining Lands Management 11(2):5159-5167.
Zhang, Z., Wu, X., Tu, C., Huang, X., Zhang, J., Fang, H., Huo, H. and Lin, C. 2020. Relationships between soil properties and the accumulation of heavy metals in different Brassica campestris L. growth stages in a karst mountainous area. Ecotoxilogy and Environmental Safety 206(111150):1-11
Biofertilizers as a Tool for Overcoming Heavy Metal Plant Stress in Indonesia: A Review
DOI: https://doi.org/10.56669/FIXF7720
ABSTRACT
The implementation of sustainable agriculture in Indonesia faces various challenges, one of which is the presence of heavy metal pollution on agricultural land. It directly threatens soil health, crop productivity, and food safety. This review explores the potential of biofertilizers as an environmentally friendly biological approach to mitigate heavy metal stress in plants. Functional microorganisms such as nitrogen-fixing bacteria (Rhizobium), phosphate-solubilizing bacteria (Bacillus, Pseudomonas), Vesicular Arbuscular Mycorrhiza (VAM), and siderophore-producing bacteria play a crucial role in this process. These microorganisms use various mechanisms to overcome heavy metal stress, including biosorption, bioaccumulation, and bioprecipitation, which mitigate rather than remove heavy metals from the soil by decreasing their bioavailability and toxicity. Their effects may therefore require periodic application to sustain bioremediation performance. In addition, biofertilizers can enhance plant resilience to abiotic stress by producing phytohormones and inducing systemic resistance. Case studies across Indonesia demonstrate that the application of biofertilizers has successfully reduced heavy metal accumulation in crops such as corn and rice on contaminated land, resulting in improved plant growth and biomass. However, the widespread adoption of biofertilizers faces obstacles, including low farmer literacy, variability in product quality, and challenges in regulatory implementation. Strengthening technical, social, and policy aspects is necessary so that biofertilizers can be widely and effectively applied to overcome heavy metal pollution issues and support sustainable agricultural practices in Indonesia.
Keywords: bioremediation, heavy metal pollution, microorganisms, sustainable agriculture
INTRODUCTION
Background
Sustainable agriculture plays a vital role in responding to global challenges to achieve a balance between ecosystem sustainability and food security, along with population growth. The world's population is expected to reach more than 10 billion by 2055, placing increased demands in the agricultural sector to meet future food needs. A sustainable agricultural system considers ecosystem, economic, and social aspects that are sustainable into the future by holding ecological, socio-economic, technical, and political principles (Dewi et al., 2024; Raidar et al., 2023). This concept emphasizes the wise management of natural resources to maintain agricultural productivity without damaging the ecosystem. Li and Yan (2020) mentioned that conventional farming systems with intensive land use and reliance on chemical fertilizers and pesticides are now considered irrelevant for maintaining because they can cause land degradation, reducing its productivity. This has led to the need to strengthen environmentally friendly agricultural practices to mitigate the negative impacts of intensive cultivation activities, which often overlook ecological aspects.
The implementation of sustainable agriculture in Indonesia faces various challenges, one of which is heavy metal pollution on agricultural land. Many areas in Indonesia have experienced heavy metal contamination, as seen in Wonosobo Regency, Central Java. Research by Dewi et al. (2023) showed that soil samples were contaminated with heavy metals of lead (Pb), cobalt (Co), nickel (Ni), chromium (Cr), arsenic (Ar), and cadmium (Cd). Soils polluted by heavy metals experience changes in soil properties such as a decrease in pH to a reduction in soil biota activity. Changes in the physical, chemical, and biological properties of soil on agricultural land contaminated by heavy metals can disrupt plant physiological processes, reduce yield production, and cause heavy metal accumulation in plant tissues. This threatens the health of humans who consume them. Heavy metals are not easily degraded, so they can accumulate in human body tissues and cause organ damage, metabolic disorders, and chronic diseases such as cancer (Sarma et al., 2024).
One of the efforts to overcome the problem of heavy metal pollution in achieving sustainable agriculture is through a biological approach, utilizing biofertilizers as bioremediation agents. The mechanism of bioremediation involves the absorption, binding, or transformation of toxic compounds into less toxic forms (Calvina et al., 2024). Biofertilizers not only provide additional nutrient supply for plants but are also able to reduce the negative impact of heavy metal pollution on agricultural land. The application of microorganisms as bioremediation agents through biofertilizers reduces the accumulation of heavy metals in plant tissues. In addition, some types of microorganisms are also able to increase plant resistance to abiotic stress by producing antioxidant compounds so that plants can grow well even on land polluted with heavy metals (Haroun et al., 2023; Kurnia 2023). Therefore, research on the use of biofertilizers in mitigating heavy metal stress in plants in Indonesia is necessary.
TYPES OF BIOFERTILIZERS THAT ARE POTENTIAL IN ADDRESSING HEAVY METALS
Biofertilizers are one of the environmentally friendly solutions that can be used to reduce the impact of heavy metals on plants. One type that has been widely studied is nitrogen-fixing bacteria, such as those from the genus Rhizobium and Bradyrhizobium. Sari and Prayudyaningsih (2020) stated that the two genera have potential as bioremediation because they can fix free nitrogen and produce plant growth hormones such as IAA (Indole Acetic Acid) to support plant growth. Rhizobium is also known to play a role in the metal bioremediation process because it has a metallothionein enzyme that can bind metals (Ambarsari and Qisthi, 2017). Other potential species include phosphate-solubilizing bacteria, such as those belonging to the Bacillus and Pseudomonas genera. Bacillus species can be bioremediation agents through enzymatic mechanisms that can reduce the toxicity of heavy metals to plants. Meanwhile, Pseudomonas can bind and accumulate metals in its cells so as to reduce the availability of metals in the soil (Aznur et al., 2022). Both bacteria can also dissolve phosphate compounds bound by heavy metals so that phosphorus (P) remains available to plants. The remediation mechanism by maintaining the availability of P in plants is also owned by Vesicular Arbuscular Mycorrhiza (VAM). Faiza et al. (2013) mentioned that heavy metal-polluted soils tend to have low P-available levels because P elements are bound by metals such as Al and Fe. VAM can degrade these bonds to increase the level of P that plant roots can absorb in heavy metal polluted soil conditions. VAMs that form symbiotic relationships with roots can also help retain heavy metals in the roots so that they do not accumulate in the upper part of the plant (Indraningsih et al., 2016).
Some bacteria, such as Rhizobium and Bacillus, are known not only as nitrogen fixers and phosphate solvents but are also capable of producing siderophore compounds that help bind heavy metals in the soil. This ability is also possessed by other bacteria that specifically produce siderophores as the main mechanism to reduce heavy metal availability to plants. Research by Nurikhsanti et al., (2024) showed that bacterial isolates from peanut rhizosphere produce catecholate-type siderophores that effectively bind heavy metals and suppress pathogen growth. Organic compound-degrading bacteria, such as those from the genus Bacillus, Pseudomonas, and Micrococcus, can also be used in heavy metal remediation due to their ability to degrade complex organic compounds into simpler compounds to obtain energy (Anggriany et al., 2018). These bacteria can break down hydrocarbon compounds that form stable bonds with heavy metals. This activity can help release metals from their binding organic compounds, thereby facilitating the process by which bacterial cells bind metal ions (Angraeni and Triajie, 2021).
MECHANISM OF BIOFERTILIZER IN OVERCOMING HEAVY METAL STRESS
Microorganisms in heavy biofertilizers have various biochemical mechanisms to reduce the toxicity of metals to plants. One of the main mechanisms of microorganisms in bioremediation is biosorption, as carried out by Pseudomonas aeruginosa bacteria. Biosorption is a passive process that involves the adsorption of metal ions by the surface of microorganism cells rich in functional groups to bind them to the cell extracellularly. Bacterial cells have negative charges located on their cell walls, such as carboxyl (COO-) and hydroxyl (OH-), so they will interact with metal ions that are usually positively charged (Anggraeni and Triajie 2021; Setiawan et al., 2019). Microorganisms also accumulate metals intracellularly through bioaccumulation mechanisms. This ability actively transports metals from the environment into bacterial cells, as shown by Streptomyces sp. (Lestari et al., 2022). Bioremediation mechanisms are also carried out by microorganisms through bioprecipitation, as performed by bacteria from Bacillus cereus. This process utilizes the metabolic activity of microorganisms to actively precipitate dissolved metal ions into stable precipitate compounds with low solubility (Nuriman et al., 2025; Octavia et al., 2018). Precipitation is one of the mechanisms carried out by some bacteria to reduce the concentration of free metals into insoluble complexes to reduce their toxicity and bioavailability (Rohmayani et al., 2024). These microbial processes mitigate heavy metal toxicity without permanently removing the metals from the soil, as they are immobilized in less soluble or less bioavailable fractions rather than eliminated from the environment.
Bioavailability is the availability of metals that can be absorbed by plants so that they can cause toxic effects on plants. Microorganisms carry out regulation of bioavailability through the process of biosorption, chelation, precipitation, and the formation of organic complexes that move metals from readily available fractions to fractions that are more stable and difficult for plants to absorb (Siaka et al., 2020; Rohmayani et al., 2024). This mechanism can suppress the accumulation of heavy metals in plant tissues, thereby reducing physiological disorders in plants. In addition to improving the polluted environment, microorganisms in biofertilizers can also induce plant resistance to abiotic stresses such as drought and heavy metals. Some examples of microorganisms that can increase plant resistance to abiotic stress are VAM and PGPR (Plant Growth-Promoting Rhizobacteria). VAM symbiosis can expand the root absorption area and improve the absorption of essential nutrients that play a role in maintaining ion balance and enzyme function in conditions exposed to heavy metals. VAM also triggers the accumulation of osmoprotectant compounds such as proline, soluble sugar, and glycine betaine, and increases antioxidant activity that plays a role in suppressing oxidative stress due to heavy metal exposure (Ilwati et al., 2024). Meanwhile, PGPR can produce phytohormones (auxins, gibberellins, cytokinins) and induce systemic resistance compounds that can activate defense genes in plants, strengthen cell walls, and increase the production of detoxification enzymes so as to increase plant tolerance to heavy metal stress (Riseh et al., 2023).
CASE STUDY OF BIOFERTILIZER UTILIZATION IN INDONESIA
Heavy metal pollution is a challenge in agricultural land management in Indonesia. Various studies conducted found that soils in various regions in Indonesia have contained heavy metals such as arsenic (Ar), cadmium (Cd), cobalt (Co), chromium (Cr), mercury (Hg), nickel (Ni), copper (Cu), and lead (Pb) (Dewi et al., 2023; Hindersah et al., 2018; Panjaitan and Sidauruk 2023). Dewi et al., (2023) mentioned that 312 soil samples from agricultural land in Wonosobo Regency, Central Java contained heavy metals with the highest to lowest content of Pb > Co > Ni > Cr > As > Cd which each had a concentration of 11.00 + 2.80 mg kg-1; 10.83 + 3.19 mg kg-1; 6.04 + 2.86 mg kg-1; 3.56 + 2.31 mg kg-1; 2.02 + 1.17 mg kg-1; and 1.23 + 0.43 mg kg-1. The concentration of heavy metals based on the study is still considered normal in the soil naturally due to the weathering activity of soil-forming rocks. However, fertilization practices can increase the content of heavy metals Pb, Cd, and Ni in the soil. Intensive fertilization activities on agricultural land continuously risk exceeding normal limits in soil for heavy metal pollution (Zhang et al. 2020).
Many efforts to control heavy metal pollution on agricultural land have been carried out, one of which is by using biological fertilizers. Indraningsih et al., (2016) stated that inoculation of Arbuscular Mycorrhizal Fungi (AMF) was able to increase the growth of corn plants in tailings soil of former gold mines from Sekotong District, West Lombok, West Nusa Tenggara which was contaminated with Hg with an initial level of 4.37 ppm. Application of AMF together with manure and dolomite produced plants with greater height, number of leaves, and biomass than the treatment without mycorrhiza. Most of the Hg absorbed by plants accumulated in the roots, suggesting that FMA plays a role in phytostabilization mechanisms that help retain heavy metals in the root zone. Although the total mercury content in soil remained relatively constant, the inoculation helped decrease the bioavailable fraction, leading to reduced translocation of metals to the upper plant parts. A similar case also occurred in the Gunung Botak area, Buru Island, Maluku. Some tailings from gold mining were deposited on agricultural land so that mercury (Hg) levels in the land were <5 mg/kg (Hindersah et al., 2018). Research by Hindersah et al. (2021) using soil samples from the site showed that the soil had a very acidic nature with initial Hg levels of 1.64 mg/kg. Biological agents from Azotobacter bacteria and cow dung compost application were used to determine their potential in reducing Hg content and its impact on corn plant growth. The results showed that the combination of 30 g/polybag compost and Azotobacter chroococcum inoculation or Azotobacter consortium was most effective in reducing Hg levels in the soil to the range of 0.92-0.98 mg/kg. The treated corn plants were able to absorb Hg up to 1.34 mg/kg, which is still classified as moderate and does not interfere with plant metabolism. Corn plant growth and biomass tended to increase in the Azotobacter inoculation treatment.
The effectiveness of biofertilizers in overcoming heavy metal pollution was also observed in rice plants. Ubaidillah et al. (2023) tested a consortium of rhizosphere bacteria consisting of Rhizobium sp., Azotobacter sp., Azospirillum sp., Pseudomonas sp., and Bacillus sp. on Pb- contaminated rice fields. The application of a bacterial consortium can reduce oxidative stress in plants due to heavy metals, as indicated by a decrease in MDA (Malondialdehyde) and ROS (Reactive Oxygen Species) levels. The results showed that Pb content in rice plant tissues decreased by 45% compared to the control, accompanied by an increase in root length by 41%, fresh weight by 32%, dry weight by 26%, and chlorophyll content by 25%. These results are reinforced by the findings of Panjaitan and Sidauruk (2023), who also used a consortium of bacteria on mustard plants in soil polluted with heavy metals Pb and Cu. The bacterial consortium used, namely Corynebacterium glutamicum and Lactobacillus sp., was able to reduce the concentration of heavy metals in the soil through the mechanism of rhizodegradation. The results showed that increasing the dose of bacterial inoculation and biochar significantly reduced the concentration of Pb and Cu in soil and plant tissues. The average reduction of Pb in soil and plants with bacterial treatment was 1.28% and 0.29%. Meanwhile, the average decrease in Cu content in soil and plants with bacterial treatment was 1.03% and 0.17%. The reduction of heavy metal concentration was followed by an increase in plant growth characterized by the number of leaves and higher plant height and greater plant wet weight in the combination treatment of biochar 20 g/plant and bacteria 10 g/plant. Overall, these studies show that biofertilizers alleviate heavy metal stress primarily through bioavailability reduction and plant tolerance rather than by eliminating metals from the soil.
FACTORS AFFECTING THE EFFECTIVENESS OF BIOFERTILIZERS
The effectiveness of biofertilizers in overcoming heavy metal stress can be influenced by the interaction between the type of microorganisms used, the type of plants planted, the environmental conditions, as well as the frequency and continuity of biofertilizer application. Soils with neutral to slightly acidic pH are optimal conditions for microorganism growth because enzymes can work well although some strains can survive at extreme pH (3.5-12.5) (Kumar et al., 2019). Other soil characteristics, such as texture and organic matter content, can also affect the effectiveness of biofertilizers. High organic matter content can improve soil structure, increase cation exchange capacity, and provide energy sources for microorganisms such as Pseudomonas, Bacillus, and Acinetobacter. These factors also require support from environmental conditions, such as suitable temperature and humidity, to maintain the optimal metabolism of microorganisms (Susilowati et al., 2024). In polluted soils, heavy metal concentrations that are too high can inhibit the enzyme function of microorganisms and plant growth, which can reduce the effectiveness of biofertilizers. However, multi-resistant bacteria such as Acinetobacter sp. IrC2 are able to survive high metal concentrations through the mechanism of accumulation and transformation of metals into less toxic forms. Microorganisms are specific to the elements that can be absorbed, so the type of microorganisms used in biofertilizers also determines the effectiveness of biofertilizers (Irawati et al., 2020; Sudaryono and Susanto, 2015). Plant species can also affect the effectiveness of biofertilizers through differences in root exudates that form specific microorganism communities in the rhizosphere. The presence of hyperaccumulator plants such as hanjuang (Cordyline fruicosa) and sunflower (Helianthus annuus) help reduce Pb, Cd, Cu, and Cr levels in the soil, thereby reducing toxic pressure on microorganisms and cultivated plants and increasing the effectiveness of biofertilizers (Widyasari et al., 2024). Moreover, since the population and activity of microorganisms tend to decline after harvest, the effectiveness of biofertilizers is also influenced by the frequency of their application. Periodic inoculation, typically once every planting cycle, helps sustain microbial performance and maintain the bioremediation potential in subsequent crops (Wang et al., 2025).
CHALLENGES AND BARRIERS IN THE UTILIZATION OF BIOFERTILIZERS IN INDONESIA
The use of biofertilizers in Indonesia faces various challenges and obstacles related to the level of knowledge, product quality, ecological suitability, and regulations. Farmers' level of literacy and confidence in the benefits and application techniques are often inadequate so that the adoption of this technology tends to be partial and inconsistent (Rafiudin et al., 2022; Irwandhi et al., 2024). The availability and quality of commercial biofertilizer products are not always uniform because the viability of microorganisms decreases during the formulation, storage, and distribution processes, thus reducing the performance of biofertilizer effectiveness when applied in the field (Fadiji et al., 2024; Santos et al., 2024). The efficacy of biofertilizers is also influenced by the adaptability of strains to local ecosystems, including soil types, microclimates, and types of cultivated crops, so the use of native strains and multilocation testing is needed to ensure consistency of performance from the laboratory to farmers' fields (Irwandhi et al., 2024; Fadiji et al., 2024). Regulatory tools such as Minister of Agriculture Regulation No. 01/PERMENTAN/SR.130/1/2019 and Minister of Agriculture Decree No. 261/KPTS/SR.310/M/4/2019 have established minimum technical specifications and registration procedures for biological fertilizers, but implementation is still constrained by limited testing facilities, weak quality control, and uncontrolled on-farm propagation practices (Kepmentan, 2019; Permentan, 2019; Santos et al., 2024).
ADVANTAGES OF BIOFERTILIZERS COMPARED TO CHEMICAL FERTILIZERS
Biofertilizers have several advantages over chemical fertilizers, especially in terms of sustainability and impact on the environment. Biofertilizers are an environmentally friendly alternative because they contain functional microorganisms that work naturally in improving the physical, chemical, and biological properties of soil without leaving harmful residues or pollutants, so that they can maintain long-term soil fertility (Putra et al., 2023). The application of biofertilizers can reduce dependence on chemical fertilizers, thereby reducing the risk of groundwater pollution and damage to soil structure due to excess urea. In addition, the presence of beneficial microorganisms such as Rhizobium, Azotobacter, and mycorrhiza in biofertilizers can improve soil health through nitrogen fixation, phosphate dissolution, increased potassium availability, decomposition of organic matter, and biological control of plant pests (Setiawati et al., 2016; Sriwahyuni and Parmila 2019). Biofertilizers improve plant health and indirectly reduce the use of chemical pesticides. Biofertilizers can increase plant resistance to pests and diseases through antagonistic mechanisms against pathogens and induction of systemic resistance in plants so that synthetic chemical inputs can be reduced (Ilwati et al., 2024; Istikorini et al., 2024).
CONCLUSIONS
Biofertilizers have great potential in overcoming heavy metal stress on agricultural land in Indonesia through the use of functional microorganisms such as Rhizobium, Bacillus, Pseudomonas, Vesicular Arbuscular Mycorrhiza (VAM), and siderophore-producing bacteria. These microorganisms can reduce heavy metal bioavailability through biosorption, bioaccumulation, bioprecipitation, chelation, degradation of organic compounds, and induce plant resistance to abiotic stress. Environmental factors influence the effectiveness of biofertilizers, the type of microorganisms used, and the type of plants cultivated. Biofertilizers have advantages over chemical fertilizers in terms of sustainability and environmental impact. However, their use still faces obstacles in the form of low farmer literacy, variable product quality, limited strain adaptation to local conditions, and suboptimal regulatory implementation. Strengthening technical, social, and policy aspects needs to be done so that the use of biofertilizers can be widely and effectively applied in the field to overcome the problem of heavy metal stress in agricultural land. In addition, periodic application of biofertilizers is necessary to maintain their effectiveness in reducing heavy metal bioavailability and supporting plant health.
REFERENCES
Ambarsari H, Qisthi A. 2017. Remediasi merkuri (Hg) pada air limbah tambang emas rakyat dengan metode lahan basah buatan terpadu. Jurnal Air Indonesia 18(2):148-156.
Anggraeni A, Triajie H. 2021. Uji kemampuan bakteri (Pseudomonas aeruginosa) dalam proses biodegradasi pencemaran logam berat timbal (Pb), di Perairan Timur Kamal Kabupaten Bangkalan. Juvenil: Jurnal Ilmiah Kelautan dan Perikanan 2(3):176-185.
Anggriany PS, Jati AWN, Murwani LI. 2018. Pemanfaatan bakteri indigenus dalam reduksi logam berat Cu pada limbah cair proses etching Printed Circuit Board (PCB). Biota: Jurnal Ilmiah Ilmu-Ilmu Hayati 3(2):87-95.
Aznur BS, Nisa SK, Septriono WA. 2022. Agen biologis potensial untuk bioremediasi logam berat. Jurnal Maiyah 1(4):186-198.
Calvina AB, Ardiana AD, Azzahra CS, Santosa NR, Miladya NF, Anwar NZ, Isnaeni. 2024. Bioremediasi cemaran tanah menggunakan biostimulant. Camellia: Clinical, Pharmaceutical, Analytical and Pharmacy Community Journal 3(2):192-204.
Dewi SBL, Aulia RV, Laily DW. 2024. Implementasi pertanian berkelanjutan dengan memanfaatkan limbah pertanian menjadi pupuk organik cair di Desa Musir Lor Kabupaten Nganjuk. Jurnal Abdi Masyarakat Indonesia 4(4):1067-1076.
Dewi T, Handayani CO, Hidayah A, Sukarjo S. 2023. Sebaran konsentrasi logam berat di lahan pertanian Kabupaten Wonosobo. Jurnal Tanah dan Sumberdaya Lahan 10(2):515-521.
Fadiji AE, Xiong C, Egidi E, Singh BK. 2024. Formulation challenges associated with microbial biofertilizers in sustainable agriculture and paths forward. Journal of Sustainable Agriculture and Environment 3(3):1-18.
Faiza R, Rahayu YS, Yuliani. 2013. Identifikasi spora jamur Mikoriza Vesikular Arbuskular (MVA) pada tanah tercemar minyak bumi di Bojonegoro. LenteraBio: Berkala Ilmiah Biologi 2(1):7-11.
Haroun M, Xie S, Awadelkareem W, Wang J, Qian X. 2023. Influence of biofertilizer on heavy metal bioremediation and enzyme activities in the soil to revealing the potential for sustainable soil restoration. Scientific Reports 13(20684):1-13.
Hindersah R, Nurhabibah G, Harryanto R. 2021. Inokulasi Azotobacter dan aplikasi kompos untuk bioremediasi tailing terkontaminasi merkuri. Jurnal Teknologi Mineral dan Batubara 17(1):39-46.
Hindersah R, Risamasu R, Kalay AM, Dewi T, Makatita I. 2018. Mercury contamination in soil, tailing and plants on agricultural fields near closed gold mine in Buru Island, Maluku. Journal of Degraded and Mining Lands Management 5(2):1027–1034.
Ilwati U, Sudharmawan AK, Sudantha IM. 2024. the effect of mycorrhiza on sorghum plants in dryland areas. Jurnal Biologi Tropis 24(2b):294-302.
Indraningsih B, Utomo WH, Handayanto E. 2016. Effects of mycorrhizae on phytoremediation of soil contaminated with small-scale gold mine tailings containing mercury. International Journal of Research in Agricultural Sciences 3(2):104-109.
Irawati W, Hasthosaputro A, Kusumawati L. 2020. Multiresistensi dan akumulasi Acinetobacter sp. IrC2 terhadap logam berat. Jurnal Biologi Papua 12(2):114-122.
Irwandhi I, Khumairah FH, Sofyan ET, Kamaluddin NN, Nurbaity A, Herdiyantoro D, Simarmata T. 2024. Current status and the significance of local wisdom biofertilizer in enhancing soil health and crop productivity for sustainable agriculture: a systematic literature review Kultivasi 23(3):287-298.
Istikorini Y, Firmansyah MA, Kurniawati F, Mubin N. 2024. Pelatihan pembuatan pupuk hayati di Desa Gondel, Kecamatan Kedungtuban, Kabupaten Blora, Jawa Tengah. Agrokreatif: Jurnal Ilmiah Pengabdian kepada Masyarakat 10(3):305-314.
[Kepmentan] Keputusan Menteri Pertanian Republik Indonesia Nomor 261/KPTS/SR.310/M/4/2019 Tentang Persyaratan Teknis Minimal Pupuk Organik, Pupuk Hayati, dan Pembenah Tanah. 2019.
Kumar A, Kumari M, Swarupa P. 2019. Characterization of pH dependent growth response of agriculturally important microbes for development of plant growth promoting bacterial consortium. Journal of Pure and Applied Microbiology 13(2):1053-1062.
Kurnia A. 2023. Identifikasi logam berat pada air kolong dan mikroba potensial untuk bioremediasi di lahan pasca penambangan timah. Jurnal Geominerba 8(1):36-43.
Lestari MD, Miranda M, Setiawati UN, Nukmal N, Setyaningrum E, Arifiyanto A, Aeny TN. 2022. Bioakumulasi dan aktivitas resistensi logam timbal (Pb) terhadap Streptomyces sp. strain I18. Jurnal Sumberdaya Alam dan Lingkungan 9(1):1-6.
Li Q, Yan J. 2020. Sustainable agriculture in the era of omics: knowledge-driven crop breeding. Genome Biology 21(154):1-5.
Nurikhsanti M, Zulkifli L, Rasmi DAC, Sedijani P. 2024. Antagonistic test of bacteria producing siderophore and protease enzymes from the rhizosfer of peanut plants on the growth of pathogenic fungus Colletotrichum gloeosporioides. Jurnal Biologi Tropis 24(1):100-108.
Nuriman M, Wibowo SS, Rezekikasari R, Agustine L, Setiawati T. 2025. Bio-reclamation evaluation of former gold mine land: pre-and post-reclamation soil management conditions. Jurnal Biologi Tropis 25(3):2457-2464.
Octavia B, Yuwono T, Taftazani A. 2018. Efek pelaparan dan akumulasi polifosfat terhadap biopresipitasi uranium pada Bacillus cereus A66. Biotropika: Journal of Tropical Biology 6(2):68-77.
Panjaitan E, Sidauruk L. 2023. Pemanfaatan biochar dan konsorsium bakteri pada remediasi tanah tercemar logam berat dan pengaruhnya terhadap hasil tanaman sawi (Brassica juncea L.). Agrotekma: Jurnal Agroteknologi dan Ilmu Pertanian 8(1):46-55.
[Permentan] Peraturan Menteri Pertanian Republik Indonesia Nomor 01 Tahun 2019 Tentang Pendaftaran Pupuk Organik, Pupuk Hayati, dan Pembenah Tanah. 2019.
Putra AP, Wicaksono LS, Gunawan SS, Putra AB, Prahesti IA, Ainiyah BQ, Nugraha DR, Basuki B. Pertanian organik: perbanyakan pupuk hayati ramah lingkungan demi upaya swasembada beras nasional. SELAPARANG: Jurnal Pengabdian Masyarakat Berkemajuan. 7(3):1849-1853.
Rafiudin RU, Siswoyo S, Maryani A. 2022. Tingkat adopsi penggunaan pupuk hayati pada budidaya padi sawah (Oryza sativa L.) di Kecamatan Bungursari Kota Tasikmalaya. SEPA: Jurnal Sosial Ekonomi Pertanian Dan Agribisnis 18(2):247-259.
Raidar U, Ramadhan F, Nufus NRK, Supriyatna MR, Pesema EA, Nabila Z, Safitri A. 2023. Penyuluhan pertanian pengendalian hama tikus dan pembuatan biosaka sebagai upaya mendukung sistem pertanian berkelanjutan di Pekon Banjarmasin. BUGUH: Jurnal Pengabdian Kepada Masyarakat 3(2):112-117.
Riseh RS, Vazvani MG, Hajabdollahi N, Thakur VK. 2023. Bioremediation of heavy metals by rhizobacteria. Applied Biochemistry and Biotechnology 195(8):4689-4711.
Rohmayani V, Romadhon N, Arimurti ARR. 2024. Identifikasi bakteri di mangrove Desa Sawohan Sidoarjo sebagai agen bioremediasi dari pencemaran logam berat. SAGO: Gizi dan Kesehatan 5(3A):733-745.
Santos F, Melkani S, Oliveira-Paiva C, Bini D, Pavuluri K, Gatiboni L, Mahmud A, Torres M, McLamore E, Bhadha JH. Biofertilizer use in the United States: definition, regulation, and prospects. Applied Microbiology and Biotechnology 108(511):1-16.
Sari R, Prayudyaningsih R. 2020. Isolasi dan potensi bakteri fiksasi nitrogen simbiotis dari bintil akar Falcataria moluccana (Miq.) Barneby & JW Grimes untuk mendukung reklamasi lahan bekas tambang nikel. Jurnal Penelitian Kehutanan Wallacea 9(2):111-120.
Sarma HH, Rajkumar A, Baro A, Das BC, Talukdar N. 2024. Impact of heavy metal contamination on soil and crop ecosystem with advanced techniques to mitigate them. Journal of Advances in Biology & Biotechnology 27(6):53-63.
Setiawan A, Basyiruddin F, Dermawan D. 2019. Biosorpsi logam berat Cu (II) menggunakan limbah Saccharomyces cereviseae. Jurnal Presipitasi: Media Komunikasi dan Pengembangan Teknik Lingkungan 16(1):29-35.
Setiawati MR, Sofyan ET, Mutaqin Z. 2016. Pengaruh pupuk hayati padat terhadap serapan N dan P tanaman, komponen hasil dan hasil padi sawah (Oryza sativa L.). Jurnal Agroekoteknologi 8(2):120-130.
Siaka IM, Rozin WA, Putra KGD. 2020. Spesiasi dan bioavailabilitas logam berat dalam sedimen Sungai Roomo Gresik. Jurnal Kimia 14(2):153-161.
Sriwahyuni P, Parmila P. 2019. Peran bioteknologi dalam pembuatan pupuk hayati. Agro Bali: Agricultural Journal 2(1):46–57
Sudaryono S, Susanto JP. 2015. Pengaruh pupuk hayati terhadap akumulasi timbal dari kompos sampah kota dalam jaringan tanaman padi. Jurnal Pangan 24(1):25-36.
Susilowati LE, Sukartono S, Akbar MF, Kusumo BH, Suriadi A, Leksono AS, Fahrudin F. 2024. Assessing the synergistic effects of inorganic, organic, and biofertilizers on rhizosphere properties and yield of maize. SAINS TANAH-Journal of Soil Science and Agroclimatology 21(1):104-116.
Ubaidillah M, Thamrin N, Cahyani FI, Fitriyah D. 2023. Bioremediation potential of rhizosphere bacterial consortium in lead (Pb) contaminated rice plants. Biodiversitas Journal of Biological Diversity 24(8):4566-4571.
Wang Z, Wang H, Qing H, Lin Q, Li J, Fu X, Kuramae EE. 2025. Periodic bioinoculations enhance soil aggregate stability through species-specific effects and interactions with the native microbiota. Geoderma 459(117345):1-10.
Widyasari NL, Rai IN, Dharma IGB, Mahendra MS. 2024. Study of controlling the content of Pb, Cu, Cd, and Cr in soils using hyperaccumulator plants. Journal of Degraded & Mining Lands Management 11(2):5159-5167.
Zhang, Z., Wu, X., Tu, C., Huang, X., Zhang, J., Fang, H., Huo, H. and Lin, C. 2020. Relationships between soil properties and the accumulation of heavy metals in different Brassica campestris L. growth stages in a karst mountainous area. Ecotoxilogy and Environmental Safety 206(111150):1-11