A biofertilizer is a substance which contains living micro-organisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply or availability of primary nutrients to the host plant.[1] Biofertilizers add nutrients through the natural processes of nitrogen fixation, solubilizing phosphorus, and stimulating plant growth through the synthesis of growth-promoting substances. The micro-organisms in biofertilizers restore the soil's natural nutrient cycle and build soil organic matter. Through the use of biofertilizers, healthy plants can be grown, while enhancing the sustainability and the health of the soil. Biofertilizers can be expected to reduce the use of synthetic fertilizers and pesticides, but they are not yet able to replace their use. As of 2024, more than 340 biofertilizer products have been approved for commercial use in the US.[2]
![](http://up.wiki.x.io/wikipedia/commons/thumb/1/18/Blue-green_algae_cultured_in_specific_media.jpg/220px-Blue-green_algae_cultured_in_specific_media.jpg)
Composition
editBiofertilizers provide "eco-friendly" organic agro-input. Rhizobium, Azotobacter, Azospirilium and blue green algae(BGA) have been in use a long time. Rhizobium inoculant is used for leguminous crops. Azotobacter can be used with crops like wheat, maize, mustard, cotton, potato and other vegetable crops. Azospirillum inoculations are recommended mainly for sorghum, millets, maize, sugarcane and wheat. Blue green algae belonging to the general cyanobacteria genera, Nostoc, Anabaena, Tolypothrix and Aulosira, fix atmospheric nitrogen and are used as inoculations for paddy crop grown both under upland and low-land conditions. Anabaena in association with water fern Azolla contributes nitrogen up to 60 kg/ha/season and also enriches soils with organic matter.[3][4] Seaweeds are rich in various types of mineral elements (potassium, phosphorus, trace elements etc.) hence they are extensively used as manure-replacement by people of coastal districts. Seaweed-fertilizer also helps in breaking down clays. Fucus is used by Irish people as biofertilizer on a large scale. In tropical countries bottom mud of dried up ponds which contain abundant blue green algae is regularly used as biofertilizer in fields.
Bacteria
editPlant-Growth Promoting Microorganisms:
- Rhizobium: Symbiotic nitrogen fixation by Rhizobium with legumes contribute substantially to total nitrogen fixation. Rhizobium inoculation is a well-known agronomic practice to ensure adequate nitrogen.[5][6] One of the most widespread specie is R. leguminosarum.
- Bradyrhizobium spp. (in particular Bradyrhizobium japonicum).[7]
- Bacillus spp. (in particular B. amyloliquefaciens, B. mojavensis, B. thuringiensis, B. licheniformis and B. subtilis).[7]
- Priestia megaterium
- Azotobacter spp. (A. chroococcum, A. vinelandii)[8]
- Pseudomonas (P. fluorescens)
- Streptomyces sp.
- Azospirilium
- Streptomyces grisoflavus[9]
Fungi
editMycorrhizal fungi such as:
- Glomus spp.
- Rhizophagus irregularis
- Gigaspora spp. (in particular G. margarita)[10]
- Trichoderma spp. (such as T. viride, T. harzianum, T. reesei, T. longibrachiatum, T. atroviride, T. koningii)
- Epichloë spp.
Archaea
edit- Nitrososphaerota[11] (in particular Nitrosocosmicus oleophilus[12])
- Euryarchaeota[11]
Organic matter
edit- Compost is commonly used as biofertilizers. It can be used directly on the soil or by using compost-derived products such as extracts or compost-tea made by fermenting compost mass. Vermicompost-based innoculants proposed by permaculture methods, Korean natural farming and JADAM[13] are examples of biofertilizers. "Seed balls" using a mixture of clay and compost proposed by the Fukuoka Method could also be seen as biofertilizer. Mixtures of compost with other organic materials such as Chitosan (which helps elicit plant defense),[14] or non-organic materials such as Montmorillonite-Illite clay and Diatomaceous earth are also often used to increase the minerals to support organism growth.
- Manure
- Duckweed[15]
Seaweed and blue green algae:
- Kelp (in particular Ascophyllum nodosum)
- Chlorella vulgaris
- Nannochloropsis
- Scenedesmus
Mechanisms
editBiofertilizers work through multiple mechanisms. Plant-Growth Promoting Rhizobacteria (PGPR) and Mycorrhiza are generally thought to increase the fixation of atmospheric nitrogen,[17] increase bioavailability of minerals in the soil[18] and synthesize phytohormones that promote growth, such as Gibberellin and Auxin.[7][11] Another mechanism proposed is the AAC-deaminase production of Bacillus species, which prevents excessive increases in the synthesis of ethylene under various stress conditions.[19]
Benefits
editBiofertilizers are cost-effective and ecofriendly in nature, and their continuous usage has been shown to enhance soil fertility.[20] Besides promoting growth by multiple mechanisms, biofertilizers produces substances suppressing phytopathogens, guarding plants from abiotic and biotic stresses and detoxification of belowground pollutants.[21] Extensive use of agrochemicals in agricultural practices has been found to cause environmental disturbances and public health hazards affecting food security and sustainability in agriculture.[22] Biofertilizers offers an alternative solution for such agrochemicals, and show yield increase of up to about 10–40% by increasing protein contents, essential amino acids, and vitamins, and by nitrogen fixation.[20]
Since a bio-fertilizer is technically living, it can symbiotically associate with plant roots. Involved microorganisms could readily and safely convert complex organic material into simple compounds, so that they are easily taken up by the plants. Microorganism function is in long duration, causing improvement of the soil fertility. It maintains the natural habitat of the soil. It increases crop yield by 20-30%, replaces chemical nitrogen and phosphorus by 30%, and stimulates plant growth. It can also provide protection against drought and some soil-borne diseases. It has also been shown that to produce a larger quantity of crops, biofertilizers with the ability of nitrogen fixation and phosphorus solubilizing would lead to the greatest possible effect.[23] They advance shoot and root growth of many crops versus control groups.[24] This can be important when implementing new seed growth.
Future Research
editBiofertilizers have been shown to have varying effects in different environments,[25] and even within the same environment. This is something that many scientists have been working on, however there is no perfect solution at this time. They however, have been shown to have the most profound effects in drier climates.[23] In the future, it is hoped that biofertilizers effects will be better controlled and regulated in all environments, as well as analysis targeted at specific species.
See also
editReferences
edit- ^ Vessey, J. Kevin (2003). "Plant growth promoting rhizobacteria as biofertilizers". Plant and Soil. 255 (2): 571–586. doi:10.1023/A:1026037216893. S2CID 37031212.
- ^ "Microbe-containing Products Advertised to Enhance Crop Growth | Vegetable Production Systems Laboratory". u.osu.edu. Retrieved 2024-08-02.
- ^ "Listing 17 bio-fertilizer microbes and their effects on the soil and plant health functions". Explogrow. 15 June 2016.
- ^ "Archived copy" (PDF). Archived from the original (PDF) on 2011-07-18. Retrieved 2010-05-03.
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: CS1 maint: archived copy as title (link) - ^ Soe, Khin Myat; Yamakawa, Takeo (2013-06-01). "Evaluation of effective Myanmar Bradyrhizobium strains isolated from Myanmar soybean and effects of coinoculation with Streptomyces griseoflavus P4 for nitrogen fixation". Soil Science and Plant Nutrition. 59 (3): 361–370. Bibcode:2013SSPN...59..361S. doi:10.1080/00380768.2013.794437. ISSN 0038-0768. S2CID 85207082.
- ^ John RP, Tyagi RD, Brar SK, Surampalli RY, Prévost D (September 2011). "Bio-encapsulation of microbial cells for targeted agricultural delivery". Critical Reviews in Biotechnology. 31 (3): 211–226. doi:10.3109/07388551.2010.513327. PMID 20879835. S2CID 207467630.
- ^ a b c Brambilla, Silvina; Stritzler, Margarita; Soto, Gabriela; Ayub, Nicolas (2022-12-01). "A synthesis of functional contributions of rhizobacteria to growth promotion in diverse crops". Rhizosphere. 24: 100611. Bibcode:2022Rhizo..2400611B. doi:10.1016/j.rhisph.2022.100611. ISSN 2452-2198.
- ^ Aasfar, Abderrahim; Bargaz, Adnane; Yaakoubi, Kaoutar; Hilali, Abderraouf; Bennis, Iman; Zeroual, Youssef; Meftah Kadmiri, Issam (2021-02-25). "Nitrogen Fixing Azotobacter Species as Potential Soil Biological Enhancers for Crop Nutrition and Yield Stability". Frontiers in Microbiology. 12. doi:10.3389/fmicb.2021.628379. ISSN 1664-302X. PMC 7947814. PMID 33717018.
- ^ Ahmed, Sohail; Hassan, Babar; Farooq, Muhammad Umer (December 2018). "Effect of biofertilizers and diatomaceous earth on life and movement of subterranean termites under laboratory conditions". International Journal of Tropical Insect Science. 38 (4): 348–352. doi:10.1017/S1742758418000103. ISSN 1742-7584. S2CID 91596645.
- ^ Klinsukon, Chaiya; Ekprasert, Jindarat; Boonlue, Sophon (December 2021). "Using arbuscular mycorrhizal fungi (Gigaspora margarita) as a growth promoter and biocontrol of leaf blight disease in eucalyptus seedlings caused by Cylindrocladium quinqueseptatum". Rhizosphere. 20: 100450. Bibcode:2021Rhizo..2000450K. doi:10.1016/j.rhisph.2021.100450. ISSN 2452-2198.
- ^ a b c Wang, Xueling; Chi, Yongkuan; Song, Shuzhen (2024-03-25). "Important soil microbiota's effects on plants and soils: a comprehensive 30-year systematic literature review". Frontiers in Microbiology. 15. doi:10.3389/fmicb.2024.1347745. ISSN 1664-302X. PMC 10999704. PMID 38591030.
- ^ Song, Geun Cheol; Im, Hyunjoo; Jung, Jihye; Lee, Soohyun; Jung, Man-Young; Rhee, Sung-Keun; Ryu, Choong-Min (March 2019). "Plant growth-promoting archaea trigger induced systemic resistance in Arabidopsis thaliana against Pectobacterium carotovorum and Pseudomonas syringae". Environmental Microbiology. 21 (3): 940–948. Bibcode:2019EnvMi..21..940S. doi:10.1111/1462-2920.14486. ISSN 1462-2912. PMID 30461142.
- ^ "JADAM Organic Farming". en.jadam.kr (in Korean). Retrieved 2024-08-02.
- ^ Guo, Jia; Cheng, Yulin (January 2022). "Advances in Fungal Elicitor-Triggered Plant Immunity". International Journal of Molecular Sciences. 23 (19): 12003. doi:10.3390/ijms231912003. ISSN 1422-0067. PMC 9569958. PMID 36233304.
- ^ Li, Jun; Otero-Gonzalez, Lila; Lens, Piet N.L.; Ferrer, Ivet; Du Laing, Gijs (December 2022). "Assessment of selenium and zinc enriched sludge and duckweed as slow-release micronutrient biofertilizers for Phaseolus vulgaris growth". Journal of Environmental Management. 324: 116397. Bibcode:2022JEnvM.32416397L. doi:10.1016/j.jenvman.2022.116397. ISSN 0301-4797. PMID 36208519.
- ^ Xu, Qiyu; Zhu, Tao; Zhao, Ruifeng; Zhao, Yang; Duan, Yangkai; Liu, Xiang; Luan, Guodong; Hu, Ruibo; Tang, Sanyuan; Ma, Xinrong; Liu, Yan; Li, Shengjun; Lu, Xuefeng (2023-12-05). "Arthrospira promotes plant growth and soil properties under high salinity environments". Frontiers in Plant Science. 14. doi:10.3389/fpls.2023.1293958. ISSN 1664-462X. PMC 10728656. PMID 38116155.
- ^ Zakry, Fitri Abdul Aziz; Shamsuddin, Zulkifli H.; Abdul Rahim, Khairuddin; Zawawi Zakaria, Zin; Abdul Rahim, Anuar (2012). "Inoculation of Bacillus sphaericus UPMB-10 to Young Oil Palm and Measurement of Its Uptake of Fixed Nitrogen Using the 15N Isotope Dilution Technique". Microbes and Environments. 27 (3): 257–262. doi:10.1264/jsme2.ME11309. PMC 4036051. PMID 22446306.
- ^ Riaz, Umair; Murtaza, Ghulam; Anum, Wajiha; Samreen, Tayyaba; Sarfraz, Muhammad; Nazir, Muhammad Zulqernain (2021), Hakeem, Khalid Rehman; Dar, Gowhar Hamid; Mehmood, Mohammad Aneesul; Bhat, Rouf Ahmad (eds.), "Plant Growth-Promoting Rhizobacteria (PGPR) as Biofertilizers and Biopesticides", Microbiota and Biofertilizers: A Sustainable Continuum for Plant and Soil Health, Cham: Springer International Publishing, pp. 181–196, doi:10.1007/978-3-030-48771-3_11, ISBN 978-3-030-48771-3, retrieved 2024-08-02
- ^ Orozco-Mosqueda, Ma. del Carmen; Glick, Bernard R.; Santoyo, Gustavo (2020-05-01). "ACC deaminase in plant growth-promoting bacteria (PGPB): An efficient mechanism to counter salt stress in crops". Microbiological Research. 235: 126439. doi:10.1016/j.micres.2020.126439. ISSN 0944-5013. PMID 32097862.
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- ^ Mącik, Mateusz; Gryta, Agata; Frąc, Magdalena (2020), Biofertilizers in agriculture: An overview on concepts, strategies and effects on soil microorganisms, Advances in Agronomy, vol. 162, Elsevier, pp. 31–87, doi:10.1016/bs.agron.2020.02.001, ISBN 978-0-12-820767-3, retrieved 2024-08-02
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- ^ Htwe, Aung Zaw; Moh, Seinn Moh; Soe, Khin Myat; Moe, Kyi; Yamakawa, Takeo (February 2019). "Effects of Biofertilizer Produced from Bradyrhizobium and Streptomyces griseoflavus on Plant Growth, Nodulation, Nitrogen Fixation, Nutrient Uptake, and Seed Yield of Mung Bean, Cowpea, and Soybean". Agronomy. 9 (2): 77. doi:10.3390/agronomy9020077.
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