Biochar application rates regulate soil nutrient availability: evidence from an 8-year field study across two soils

Abstract

While biochar is widely promoted as a soil amendment for enhancing nutrient availability and carbon sequestration, its long-term effectiveness across diverse soil types under intensive cultivation remains poorly understood. This study quantified temporal dynamics of biochar-induced nutrient changes across two contrasting soils (Dystrudept and Hapludult) over eight years (2018–2025), evaluating five application rates (0, 5, 15, 20, and 40 t ha⁻¹) through 18 repeated soil samplings under continuous tobacco cultivation. Biochar application produced strong initial responses in soil pH, organic carbon (SOC reaching 83.59 g kg⁻¹ at 40 t ha⁻¹ in Hapludult), and available nutrients, but these effects progressively diminished, with complete convergence across all treatments by year 6–8 regardless of initial application rate or soil type—a critical finding that fundamentally challenges assumptions of permanent biochar effectiveness. Structural equation modeling identified pH-mediated pathways (λ = 0.99***) driving base cation availability, with temporal factors consistently eroding nutrient pools. Strikingly, the sandy loam Dystrudept exhibited 40% longer persistence of significant treatment effects than the clay loam Hapludult, directly contradicting conventional CEC-based predictions and revealing that crop uptake and leaching override texture-based retention under intensive management. The 20 t ha⁻¹ application rate emerged as optimal, while rates above 40 t ha⁻¹ accelerated nutrient depletion without extending benefit duration—demonstrating clear threshold effects previously unquantified in long-term field trials. This study suggests that biochar may function primarily as a medium-term amendment (3–5 years) rather than a permanent conditioner. In intensive cropping systems, maintaining the agronomic benefits of biochar may therefore require moving beyond single high-rate applications toward soil-specific optimization and potentially periodic reapplication strategies.

Graphical Abstract

Keywords

Biochar / Rate / Long term experiment / Soil nutrient / Crop quality / SEM

References

[1] Abbas T, Rizwan M, Ali S, Adrees M, Zia-ur-Rehman M, Qayyum MF, Ok YS, Murtaza G. Effect of biochar on alleviation of cadmium toxicity in wheat (Triticum aestivum L.) grown on Cd-contaminated saline soil. Environ Sci Pollut Res, 2018, 25(26): 25668-25680.

[2] Agbede TM, Adekiya AO. Influence of biochar on soil physicochemical properties, erosion potential, and maize (Zea mays L.) grain yield under sandy soil condition (article). Commun Soil Sci Plant Anal, 2020, 51(20): 2559-2568.

[3] Bao Z, Dai W, Su X, Liu Z, An Z, Sun Q, Jing H, Lin L, Chen Y, Meng J. Long-term biochar application promoted soil aggregate-associated potassium availability and maize potassium uptake. Glob Change Biol Bioenergy, 2024, 16(4): 13134.

[4] Biederman LA, Harpole WS. Biochar and its effects on plant productivity and nutrient cycling: a meta-analysis. GCB Bioenergy, 2013, 5(2): 202-214.

[5] Cooper J, Greenberg I, Ludwig B, Hippich L, Fischer D, Glaser B, Kaiser M. Effect of biochar and compost on soil properties and organic matter in aggregate size fractions under field conditions. Agric Ecosyst Environ, 2020, 295: 106882.

[6] Dai YH, Zheng H, Jiang ZX, Xing BS. Combined effects of biochar properties and soil conditions on plant growth: a meta-analysis (Article). Sci Total Environ, 2020, 713. ArticleID: 11

[7] Dong XL, Singh BP, Li GT, Lin QM, Zhao XR. Biochar application constrained native soil organic carbon accumulation from wheat residue inputs in a long-term wheat-maize cropping system. Agric Ecosyst Environ, 2018, 252: 200-207.

[8] Fan Q, Sun J, Chu L, Cui L, Quan G, Yan J, He Y. Effects of chemical oxidation on surface oxygen-containing functional groups and adsorption behavior of biochar. Chemosphere, 2018, 207: 33-40.

[9] Haider G, Steffens D, Müller C, Kammann CI. Biochar reduced nitrate leaching and improved soil moisture content without yield improvements in a four-year field study. Agric Ecosyst Environ, 2017, 237: 80-94.

[10] Han L, Sun K, Jin J, Xing B. Some concepts of soil organic carbon characteristics and mineral interaction from a review of literature. Soil Biol Biochem, 2016, 94: 107-121.

[11] He YH, Zhou XH, Jiang LL, Li M, Du ZG, Zhou GY, Shao JJ, Wang XH, Xu ZH, Bai SH, Wallace H, Xu CY. Effects of biochar application on soil greenhouse gas fluxes: a meta-analysis. GCB Bioenergy, 2017, 9(4): 743-755.

[12] Hu L, Cao L, Zhang R. Bacterial and fungal taxon changes in soil microbial community composition induced by short-term biochar amendment in red oxidized loam soil. World J Microbiol Biotechnol, 2014, 30(4): 1085-1092.

[13] Jaffar MT, Zhen S, Han JL, Zhang JG, Dar A, Mushtaq Z, Hussain Q, Zahir ZA, Siddique KHM. Orange peel biochar: An effective amendment to improve the maize resilience by regulating the soil enzymatic activities, nutrient uptake, and ionic homeostasis under salinity stress. Industrial Crops Products, 2024, 222: 120081.

[14] Joseph SD, Camps-Arbestain M, Lin Y, Munroe P, Chia CH, Hook J, van Zwieten L, Kimber S, Cowie A, Singh BP, Lehmann J, Foidl N, Smernik RJ, Amonette JE. An investigation into the reactions of biochar in soil. Aust J Soil Res, 2010, 48: 501-515.

[15] Soil Survey Staff. Keys to Soil Taxonomy, 2014. Washington, DC, USDA–Natural Resources Conservation Service

[16] Khan S, Shah Z, Mian IA, Dawar K, Tariq M, Khan B, Mussarat M, Amin H, Ismail M, Ali S, Shah T, Alamri S, Siddiqui MH, Adnan M, Romman M, Fahad S, Nouman A, Kamal A. Soil fertility, N-2 fixation and yield of chickpea as influenced by long-term biochar application under mung-chickpea cropping system (article). Sustainability, 2020, 12(21. ArticleID: 14

[17] Kumar Y, Ren W, Tao HY, Tao B, Lindsey LE. Impact of biochar amendment on soil microbial biomass carbon enhancement under field experiments: a meta-analysis. Biochar, 2025, 7(1): 6.

[18] Lehmann J, Rillig MC, Thies J, Masiello CA, Hockaday WC, Crowley D. Biochar effects on soil biota - a review (review). Soil Biol Biochem, 2011, 43(9): 1812-1836.

[19] Lehmann J, Cowie A, Masiello CA, Kammann C, Woolf D, Amonette JE, Whitman T. Biochar in climate change mitigation. Nat Geosci, 2021, 14(12): 883-892.

[20] Lehmann J, Joseph S (2015) Biochar for environmental management: science, technology and implementation. Routledge, London. https://doi.org/10.4324/9780203762264

[21] Lin Y, Munroe P, Joseph S, Kimber S, Van Zwieten L. Nanoscale organo-mineral reactions of biochars in ferrosol. Plant Soil, 2023, 357(1): 369-380.

[22] Littell RC, Henry PR, Ammerman CB. Statistical analysis of repeated measures data using SAS procedures. J Anim Sci, 1998, 76: 1216-1231.

[23] Littell RC, Pendergast J, Natarajan R. Modelling covariance strucutre in the analysis of repeated measures data. Stat Med, 2000, 19(13): 1793-1819.

[24] Liu X, Mao P, Li L, Ma J. Impact of biochar on yield-scaled greenhouse gas intensity: a meta-analysis. Sci Total Environ, 2022, 656: 969-976.

[25] Liu YF, Wang ML, Yin SJ, Xie LK, Qu XL, Fu HY, Shi Q, Zhou F, Xu FL, Tao S, Zhu DQ. Comparing photoactivities of dissolved organic matter released from rice straw-pyrolyzed biochar and composted rice straw. Environ Sci Technol, 2022, 56(4): 2803-2815.

[26] Liu S, Li JS, Zhou ZM, Steinberg CEW, Pan B, Tao S, Xing BS. Biochar soil addition alters ant functional traits as exemplified with three species. Biochar, 2024.

[27] Ma N, Zhang L, Zhang Y, Yang L, Yu C, Yin G, Chen X. Biochar improves soil aggregate stability and water availability. PLoS ONE, 2024, 11(5. ArticleID: e0154091

[28] Mia S, Dijkstra FA, Singh B. Long-term aging of biochar: a molecular understanding with agricultural and environmental implications. Adv Agron, 2017, 141: 1-51.

[29] Nguyen BT, Lehmann J, Kinyangi J, Smernik R, Riha SJ, Engelhard MH. Long-term black carbon dynamics in cultivated soil. Biogeochemistry, 2008, 89(3): 295-308.

[30] Nguyen TTN, Xu CY, Tahmasbian I, Che RX, Xu ZH, Zhou XH, Wallace HM, Bai SH. Effects of biochar on soil available inorganic nitrogen: a review and meta-analysis. Geoderma, 2017, 288: 79-96.

[31] Omokaro GO, Kornev KP, Nafula ZS, Chikukula AA, Osayogie OG, Efeni OS. Biochar for sustainable soil management: enhancing soil fertility, plant growth and climate resilience. Farming Syst, 2025, 3(4. ArticleID: 100167

[32] Qian L, Chen B, Hu D. Effective alleviation of Aluminum phytotoxicity by manure-derived biochar. Environ Sci Technol, 2013, 47(6): 2737-2745.

[33] Razzaghi F, Obour PB, Arthur E. Does biochar improve soil water retention? A systematic review and metaanalysis. Geoderma, 2020, 361. ArticleID: 114055

[34] Ronco M, Tárraga JM, Muñoz J, Piles M, Marco ES, Wang Q, Espinosa MTM, Ponserre S, Camps-Valls G. Exploring interactions between socioeconomic context and natural hazards on human population displacement. Nat Commun, 2023, 14(1. ArticleID: 8004

[35] Schmidt HP, Kammann C, Hagemann N, Leifeld J, Bucheli TD, Sánchez-Monedero MA, Cayuela ML. Biochar in agriculture - a systematic review of 26 global meta-analyses. GCB Bioenergy, 2021, 13(11): 1708-1730.

[36] da Silva EC, da Silva Sales MV, Aleixo S, Gama-Rodrigues AC, Gama-Rodrigues EF. Does structural equation modeling provide a holistic view of phosphorus acquisition strategies in soils of Amazon Forest?. J Soil Sci Plant Nutr, 2022, 22(3): 3334-3347.

[37] Tama RAZ, Hoque MM, Liu Y, Alam MJ, Yu M. An application of partial least squares structural equation modeling (PLS-SEM) to examining farmers’ behavioral attitude and intention towards conservation agriculture in Bangladesh. Agriculture, 2023.

[38] Tusar HM, Uddin MK, Mia S, Suhi AA, Wahid SBA, Kasim S, Sairi NA, Alam Z, Anwar F. Biochar-acid soil interactions—a review. Sustainability, 2023, 15(18. ArticleID: 13366

[39] Vaccari FP, Baronti S, Lugato E, Genesio L, Castaldi S, Fornasier F, Miglietta F. Biochar as a strategy to sequester carbon and increase yield in durum wheat. Eur J Agron, 2011, 34(4): 231-238.

[40] Wang B, Lehmann J, Hanley K, Hestrin R, Enders A. Adsorption and desorption of ammonium by maple wood biochar as a function of oxidation and pH. Chemosphere, 2015, 138: 120-126.

[41] Wang L, Ok YS, Tsang DC, Alessi DS, Rinklebe J, Wang H, Hou D. New trends in biochar pyrolysis and modification strategies: feedstock, pyrolysis conditions, sustainability concerns and implications for soil amendment. Soil Use Manag, 2020, 36(3): 358-386.

[42] Yang X, Liu J, McGrouther K, Huang H, Lu K, Guo X, Wang H. Effect of biochar on the extractability of heavy metals (Cd, Cu, Pb, and Zn) and enzyme activity in soil. Environ Sci Pollut Res, 2016, 23(2): 974-984.

[43] Ye L, Camps-Arbestain M, Shen Q, Lehmann J, Singh B, Sabir M. Biochar effects on crop yields with and without fertilizer: a meta-analysis of field studies using separate controls. Soil Use Manag, 2020, 36(1): 2-18.

[44] Zhang J, Li C, Li G, He Y, Yang J, Zhang J. Effects of biochar on heavy metal bioavailability and uptake by tobacco (Nicotiana tabacum) in two soils. Agric Ecosyst Environ, 2021.

[45] Zhang W, Pang J, Qi J, Lu Y, Liu J, Yu M, Li H, Wang E, Lambers H. Biochar’s dual impact on soil acidity management and crop yield enhancement in acidic soils: a meta-analysis. Plant Soil, 2025, 514(2): 1849-1865.

[46] Zhao B, O’Connor D, Zhang J, Peng T, Shen Z, Tsang DC, Hou D. Effect of pyrolysis temperature, heating rate, and residence time on rapeseed stem derived biochar. J Clean Prod, 2018, 174: 977-987.

Funding

The Biochar research Center, Bijie Tobacco Company of Guizhou Province(2022520500240197)

the (Chinese) Agricultural Science and Technology Innovation Program(ASTIP-TRIC02)

Shandong Provincial Natural Science Foundation(ZR2023MC137)

RIGHTS & PERMISSIONS

The Author(s)