Particle size influences biochar-mediated control of pepper Phytophthora blight: linking released compounds to soil microbial disease suppression

Abstract

Biochar is a promising soil amendment for controlling plant diseases, but the influence of its particle size on disease suppression remains unclear. This study focused on the differential mechanisms of fine and coarse biochars in controlling pepper Phytophthora blight, linking biochar-released compounds (BRCs) to soil microbial disease suppression. The pot experiment revealed that fine biochar provided a stronger initial suppression of disease severity and pathogen abundance, but these effects diminished over time, whereas coarse biochar provided a more durable control effect. Similar time-dependent effects were observed for the increase in total and biocontrol microbial abundances. The mesh-bag experiment confirmed that fine biochar rapidly released minerals and labile organic carbon (LOC) in the early stage. This initial release significantly increased the abundances of total bacteria, total fungi, Pseudomonas, Trichoderma, and Penicillium, as well as the antagonist percentages of total bacteria and fungi, while suppressing Phytophthora capsici. However, the reduced release of BRCs in the later stage markedly weakened these effects. In contrast, coarse biochar provided more durable suppression through a slower, more sustained release of BRCs, resulting in a greater improvement in microbial properties during the later stage. Mantel tests and PLS-PM analysis indicated that electrical conductivity (representing minerals) and LOC were the key drivers that enhanced microbial abundance and antagonism, which in turn effectively suppressed the pathogen. This study reveals that biochar particle size influences the release rate of BRCs, resulting in a time-dependent control effect. These findings provide new insights into developing precise and sustainable disease control strategies.

Keywords

Biochar / Particle size / Biochar-released compounds / Soil microorganisms / Pepper Phytophthora blight

References

[1] Adusei-Fosu K, De Bhowmick G, Akhter A, Abbas MT. Al-Wabel MI, Bashir S, Al-Safi AK. Biochar as a Management Tool for Soilborne Fusarium and Phytophthora Pathogens. Biochar - Latest Developments and Applications, 2025, London, IntechOpen117

[2] Afridi MS, Fakhar A, Kumar A, Ali S, Medeiros FHV, Muneer MA, Ali H, Saleem M. Harnessing microbial multitrophic interactions for rhizosphere microbiome engineering. Microbiol Res, 2022, 265 127199

[3] Azeem M, Sun T-R, Jeyasundar PGSA, Han R-X, Li H, Abdelrahman H, Shaheen SM, Zhu Y-G, Li G. Biochar-derived dissolved organic matter (BDOM) and its influence on soil microbial community composition, function, and activity: a review. Crit Rev Environ Sci Technol, 2023, 53(19): 1912-1934

[4] Azeem M, Wang J, Kubwimana JJ, Kazmi SSH, Khan ZH, He K, Han R. Biochar-derived dissolved organic matter (BDOM) shifts fungal community composition: BDOM-soil DOM interaction. Appl Soil Ecol, 2025, 207 105916

[5] Bekchanova M, Kuppens T, Cuypers A, Jozefczak M, Malina R. Biochar's effect on the soil carbon cycle: a rapid review and meta-analysis. Biochar, 2024, 6(1): 88

[6] Bolan S, Sharma S, Mukherjee S, Kumar M, Rao CS, Nataraj KC, Singh G, Vinu A, Bhowmik A, Sharma H, El-Naggar A, Chang SX, Hou D, Rinklebe J, Wang H, Siddique KHM, Abbott LK, Kirkham MB, Bolan N. Biochar modulating soil biological health: a review. Sci Total Environ, 2024, 914 169585

[7] Chen J, Li S, Liang C, Xu Q, Li Y, Qin H, Fuhrmann JJ. Response of microbial community structure and function to short-term biochar amendment in an intensively managed bamboo (Phyllostachys praecox) plantation soil: effect of particle size and addition rate. Sci Total Environ, 2017, 574: 24-33

[8] Chen P, Zhang JL, Li M, Fang F, Hu JD, Sun ZW, Zhang AS, Gao XX, Li J. Synergistic effect of Bacillus subtilis and Paecilomyces lilacinus in alleviating soil degradation and improving watermelon yield. Front Microbiol, 2023, 13: 1101975

[9] Dai Z, Xiong X, Zhu H, Xu H, Leng P, Li J, Tang C, Xu J. Association of biochar properties with changes in soil bacterial, fungal and fauna communities and nutrient cycling processes. Biochar, 2021, 3(3): 239-254

[10] Dorjee L, Nishmitha K, Pattanayak S, Wangmu T, Meshram S, Chongtham S, Gogoi R. Biochar: a comprehensive review on a natural approach to plant disease management. J Pure Appl Microbiol, 2024, 18(1): 58

[11] Drigo B, van Veen JA, Kowalchuk GA. Specific rhizosphere bacterial and fungal groups respond differently to elevated atmospheric CO₂. ISME J, 2009, 3: 1204-1217

[12] Dror B, Amutuhaire H, Frenkel O, Jurkevitch E, Cytryn E. Identification of bacterial populations and functional mechanisms potentially involved in biochar-facilitated antagonism of the soilborne pathogen Fusarium oxysporum. Phytobiomes J, 2022, 6(2): 139-150

[13] Gao X, Cheng H-Y, Del Valle I, Liu S, Masiello CA, Silberg JJ. Charcoal disrupts soil microbial communication through a combination of signal sorption and hydrolysis. ACS Omega, 2016, 1(2): 226-233

[14] Hagn A, Wallisch S, Radl V, Munch JC, Schloter M. A new cultivation independent approach to detect and monitor common Trichoderma species in soils. J Microbiol Methods, 2007, 69: 86-92

[15] Hou J, Pugazhendhi A, Phuong TN, Thanh NC, Brindhadevi K, Velu G, Lan Chi NT, Yuan D. Plant resistance to disease: using biochar to inhibit harmful microbes and absorb nutrients. Environ Res, 2022, 214 113883

[16] Hu J, Tang H, Wang YZ, Yang C, Gao M, Tsang YF, Li J. Effect of dissolved solids released from biochar on soil microbial metabolism. Environ Sci Process Impacts, 2022, 24(3): 598-608

[17] Jin X, Bai Y, Rahman MKU, Kang X, Pan K, Wu F, Pommier T, Zhou X, Wei Z. Biochar stimulates tomato roots to recruit a bacterial assemblage contributing to disease resistance against Fusarium wilt. iMeta, 2022, 1 e37

[18] Joseph S, Cowie AL, Van Zwieten L, Bolan N, Budai A, Buss W, Cayuela ML, Graber ER, Ippolito JA, Kuzyakov Y, Luo Y, Ok YS, Palansooriya KN, Shepherd J, Stephens S, Weng Z, Lehmann J. How biochar works, and when it doesn't: a review of mechanisms controlling soil and plant responses to biochar. GCB Bioenergy, 2021, 13(11): 1731-1764

[19] Kerner P, Struhs E, Mirkouei A, Aho K, Lohse KA, Dungan RS, You Y. Microbial responses to biochar soil amendment and influential factors: a three-level meta-analysis. Environ Sci Technol, 2023, 57(50): 19838-19848

[20] Li T, Choi K, Jung B, Ji S, Kim D, Seo MW, Lee J, Lee S-H. Biochar inhibits ginseng root rot pathogens and increases soil microbiome diversity. Appl Soil Ecol, 2022, 169 104229

[21] Li S, Yang L, Jiang T, Ahmed W, Mei F, Zhang J, Zhang T, Yang Y, Peng X, Shan Q, Luo D, Zhao Z. Unraveling the role of pyrolysis temperature in biochar-mediated modulation of soil microbial communities and tobacco bacterial wilt disease. Appl Soil Ecol, 2025, 206 105845

[22] Liao W, Thomas SC. Biochar particle size and post-pyrolysis mechanical processing affect soil pH, water retention capacity, and plant performance. Soil Syst, 2019, 3(1 14

[23] Ma S, Jing F, Sohi SP, Chen J. New insights into contrasting mechanisms for PAE adsorption on millimeter, micron- and nano-scale biochar. Environ Sci Pollut Res, 2019, 2618): 18636-18650

[24] Medeiros EV, da Silva LF, da Araújo Silva JS, Moreira KA, da Silva Tenório D. Biochar and Trichoderma spp. in management of plant diseases caused by soilborne fungal pathogens: a review and perspective. Res Soc Dev, 2021, 10(15 e296101522465

[25] Ogundeji AO, Li Y, Liu X, Meng L, Sang P, Mu Y, Wu H, Ma Z, Hou J, Li S. Eggplant by grafting enhanced with biochar recruits specific microbes for disease suppression of Verticillium wilt. Appl Soil Ecol, 2021, 163 103912

[26] Poveda J, Martínez-Gómez Á, Fenoll C, Escobar C. The use of biochar for plant pathogen control. Phytopathology, 2021, 1119): 1490-1499

[27] Purakayastha TJ, Bera T, Dey S, Pande P, Kumari S, Bhowmik A. Biochar aided priming of carbon and nutrient availability in three soil orders of India. Sci Rep, 2024, 14: 8420

[28] Sanogo S, Lamour K, Kousik CS, Lozada DN, Parada-Rojas CH, Quesada-Ocampo LM, Wyenandt CA, Babadoost M, Hausbeck MK, Hansen Z, Ali E, McGrath MT, Hu J, Crosby K, Miller SA. Phytophthora capsici, 100 years later: research mile markers from 1922 to 2022. Phytopathology, 2023, 113(6): 921-930

[29] Sarfraz R, Yang W, Wang S, Zhou B, Xing S. Short term effects of biochar with different particle sizes on phosphorous availability and microbial communities. Chemosphere, 2020, 256 126862

[30] Sharma M, Kaushik R, Pandit MK, Lee Y-H. Biochar-induced microbial shifts: advancing soil sustainability. Sustainability, 2025, 17(4): 1748

[31] Shyam S, Ahmed S, Joshi SJ, Sarma H. Biochar as a soil amendment: implications for soil health, carbon sequestration, and climate resilience. Discover Soil, 2025, 2: 18

[32] Sovova S, Mravcova L, Porizka J, Kubikova L, Kalina M. The effect of biochar particle size on the leaching of organic molecules and macro- and microelements. Agronomy, 2024, 14102346

[33] Suanthie Y, Cousin MA, Woloshuk CP. Multiplex real-time PCR for detection and quantification of mycotoxigenic Aspergillus, Penicillium and Fusarium. J Stored Prod Res, 2009, 45: 139-145

[34] Tang E, Liao W, Thomas SC. Optimizing biochar particle size for plant growth and mitigation of soil salinization. Agronomy, 2023, 13(5): 1394

[35] Tian GL, Bi YM, Jiao XL, Zhang XM, Li JF, Niu FB, Gao WW. Application of vermicompost and biochar suppresses Fusarium root rot of replanted American ginseng. Appl Microbiol Biotechnol, 2021, 105246977-6991

[36] Tirol-Padre A, Ladha JK. Assessing the reliability of permanganate oxidizable carbon as an index of soil labile carbon. Soil Sci Soc Am J, 2004, 68: 969-978

[37] Upadhyay V, Choudhary KK, Agrawal SB. Use of biochar as a sustainable agronomic tool, its limitations and impact on environment: a review. Discover Agriculture, 2024, 2: 20

[38] Wang QJ, Ma Y, Yang H, Chang ZZ. Effect of biofumigation and chemical fumigation on soil microbial community structure and control of pepper Phytophthora blight. World J Microbiol Biotechnol, 2014, 30: 507-518

[39] Wang GF, Ma Y, Guo DJ, Cao Y, Luo DX, Zhao JF, Sun YD. Application-rate-dependent effects of straw biochar on control of Phytophthora blight of chilli pepper and soil properties. Acta Pedol Sin, 2017, 54(1): 204-215

[40] Wang GF, Ma Y, Govinden R, Chenia HY, Luo J, Ren GD. Suppression of Phytophthora blight of pepper by biochar amendment is associated with improved soil bacterial properties. Biol Fertil Soils, 2019, 55(8): 813-824

[41] Wang GF, Ma Y, Chenia HY, Govinden R, Luo J, Ren GD. Biochar-mediated control of Phytophthora blight of pepper is closely related to the improvement of the rhizosphere fungal community. Front Microbiol, 2020, 11: 1427

[42] Wang X, Chi Y, Song S. Important soil microbiota's effects on plants and soils: a comprehensive 30-year systematic literature review. Front Microbiol, 2024, 15: 1347745

[43] Wu Z, Fan Y, Zhou Z, Hao X, Kang S. Interaction between biochar particle size and soil salinity levels on soil properties and tomato yield. Biochar, 2025, 7(1): 30

[44] Yan M, Wu M, Liu M, Li G, Liu K, Qiu C, Bao Y, Li Z. Comparative analysis on root exudate and rhizosphere soil bacterial assembly between tomatoes and peppers infected by Ralstonia. Chem Biol Technol Agric, 2024, 11136

[45] Yang Y, Qiu K, Xie Y, Li X, Zhang S, Liu W, Huang Y, Cui L, Wang S, Bao P. Geographical, climatic, and soil factors control the altitudinal pattern of rhizosphere microbial diversity and its driving effect on root zone soil multifunctionality in mountain ecosystems. Sci Total Environ, 2023, 904 166932

[46] Zhang XL, Song JT, Li RX, Zhou L, Li T, Wang X, Zhou QX. Artificial electron snorkels reduce CH₄ emissions in paddy soil: regulation of the electron transfer pathway and microbial community ecology. Soil Biol Biochem, 2024, 196 109504

[47] Zhang P, Chang F, Huo L, Yao Z, Luo J. Impacts of biochar pyrolysis temperature, particle size, and application rate on water retention of loess in the semiarid region. Water, 2025, 17169

[48] Zhao R, Wu J, Jiang C, Liu F. Effects of biochar particle size and concomitant nitrogen fertilization on soil microbial community structure during the maize seedling stage. Environ Sci Pollut Res, 2020, 271010836-10849

[49] Zheng T, Ouyang SH, Zhou QX. Synthesis, characterization, safety design, and application of NPs@BC for contaminated soil remediation and sustainable agriculture. Biochar, 2023, 5: 5

[50] Zheng ZQ, Liu WT, Zhou QX, Li JT, Zeb A, Wang Q, Lian YH, Shi RY, Wang J. Effects of co-modified biochar immobilized laccase on remediation and bacterial community of PAHs-contaminated soil. J Hazard Mater, 2023, 443 130372

[51] Zhou QX, Li DD, Wang T, Hu XG. Leaching of graphene oxide nanosheets in simulated soil and their influences on microbial communities. J Hazard Mater, 2021, 404 124046

Funding

National Natural Science Foundation of China(32201401)

National Key Research and Development Program of China(2023YFD1702203)

RIGHTS & PERMISSIONS

The Author(s)