Toxicity induced by heavy metals deteriorates soil fertility status. It also adversely affects the growth and yield of crops. These heavy metals become part of the food chain when crops are cultivated in areas where heavy metals are beyond threshold limits. Cadmium (Cd) and nickel (Ni) are considered the most notorious ones among different heavy metals. The high water solubility of Cd made it a potential toxin for plants and their consumers. Accumulation of Ni in plants, leaves, and fruits also deteriorates their quality and causes cancer in humans when such a Ni-contaminated diet is used regularly. Both Cd and Ni also compete with essential nutrients of plants, making the fertility status of soil poor. To overcome this problem, the use of activated carbon biochar can play a milestone role. In the recent past application of activated carbon biochar is gaining more and more attention. Biochar sorb the Cd and Ni and releases essential micronutrients that are part of its structure. Many micropores and high cation exchange capacity make it the most acceptable organic amendment to improve soil fertility and immobilize Cd and Ni. In addition to improving water and nutrients, soil better microbial proliferation enhances the soil rhizosphere ecosystem and nutrient cycling. This review has covered Cd and Ni harmful effects on crop yield and their immobilization by activated carbon biochar. The focus was made to elaborate on the positive effects of biochar on crop yield and soil health.

City of Scientific Research and Technology Applications New Burg Al Arab Alexandria Egypt

Department of agricultural Extension and Rural society College of food sciences and agriculture King Saud University Riyadh PO Box 2460 11451 Saudi Arabia

Department of Agronomy The University of Haripur Haripur 22620 Pakistan

Department of Botany and Microbiology College of Science King Saud University PO Box 2455 Riyadh 11451 Saudi Arabia

Department of Botany University of Central Punjab Punjab Pakistan

Department of Geology and Pedology Faculty of Forestry and Wood Technology Mendel University in Brno Zemedelska 3 61300 Brno Czech Republic

Department of Soil Science and Plant Nutrition Faculty of Agriculture Ankara University 06110 Ankara Turkey

Department of Soil Science Faculty of Agricultural Sciences and Technology Bahauddin Zakariya University Multan 60800 Punjab Pakistan

Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource College of Tropical Crops Hainan University Haikou 570228 China

Institute of Bioproduct Development Skudai Johor Bahru Johor Malaysia

Laboratory of Tropical and Mediterranean Symbioses CIRAD Montpellier France

Malaysia Japan Advanced Research Centre 84600 Pagoh Johor Malaysia

Pesticide Quality Control Laboratory Multan 60000 Punjab Pakistan

School of Chemical and Energy Engineering Faculty of Engineering Universiti Teknologi Malaysia Skudai Johor Bahru Johor Malaysia

See more in PubMed

Abbas M., Anwar J., Zafar-ul-Hye M., Khan R.I., Saleem M., Rahi A.A., Danish S., Datta R. Effect of seaweed extract on productivity and quality attributes of four onion cultivars. Horticulturae. 2020;6:28.

Abid M., Danish S., Zafar-ul-Hye M., Shaaban M., Iqbal M.M., Rehim A., Qayyum M.F., Naqqash M.N. Biochar increased photosynthetic and accessory pigments in tomato (Solanum lycopersicum L.) plants by reducing cadmium concentration under various irrigation waters. Environ. Sci. Pollut. Res. 2017;24:22111–22118. doi: 10.1007/s11356-017-9866-8. PubMed DOI

Adriano, 2001. Trace elements in terrestrial environments. In: Biogeochemistry, bioavailability and risks of metals. Springer-Verlag, New York, p. 374. 10.2134/jeq2002.3740.

Agegnehu G., Nelson P.N., Bird M.I. Crop yield, plant nutrient uptake and soil physicochemical properties under organic soil amendments and nitrogen fertilization on Nitisols. Soil Tillage Res. 2016;160:1–13. doi: 10.1016/j.still.2016.02.003. DOI

Ahmad M.S.A., Ashraf M., Hussain M. Phytotoxic effects of nickel on yield and concentration of macro- and micro-nutrients in sunflower (Helianthus annuus L.) achenes. J. Hazard. Mater. 2011;185:1295–1303. doi: 10.1016/j.jhazmat.2010.10.045. PubMed DOI

Ahmad, P., Rasool, S., 2014. Emerging technologies and management of crop stress tolerance, Emerging Technologies and Management of Crop Stress Tolerance: Biological Techniques. 10.1016/C2013-0-19047-2

Al-Qurainy F. Toxicity of heavy metals and their molecular detection on Phaseolus vulgaris (L.) Aust. J. Basic Appl. Sci. 2009;3:3025–3035.

Ali K., Wang X., Riaz M., Islam B., Khan Z.H., Shah F., Munsif F., Ijaz Ul Haq S. Biochar: an eco-friendly approach to improve wheat yield and associated soil properties on sustainable basis. Pakistan J. Bot. 2019;51:1255–1261. doi: 10.30848/PJB2019-4(7). DOI

Ali U., Shaaban M., Bashir S., Gao R., Fu Q., Zhu J., Hu H. Rice straw, biochar and calcite incorporation enhance nickel (Ni) immobilization in contaminated soil and Ni removal capacity. Chemosphere. 2020;244 doi: 10.1016/j.chemosphere.2019.125418. PubMed DOI

Alloway B.J. Heavy metals in soils. Heavy Metals in Soils. 1995:411–428. doi: 10.1007/978-94-011-1344-1. DOI

Amonette J., Joseph S. In: Biochar for Environmental Management: Science and Technology. Amonette J., Joseph S., editors. Earthscan; London, UK: 2009. Characteristics of biochar - micro-chemical properties; pp. 33–52. DOI

Arif M., Ali K., Jan M.T., Shah Z., Jones D.L., Quilliam R.S. Integration of biochar with animal manure and nitrogen for improving maize yields and soil properties in calcareous semi-arid agroecosystems. F. Crop. Res. 2016;195:28–35. doi: 10.1016/j.fcr.2016.05.011. DOI

Barsukova V.S., Gamzikova O.I. Effects of nickel surplus on the element content in wheat varieties contrasting in Ni resistance. Agrokhimiya. 1999;1:80–85.

Basu A., Prasad P., Das S.N., Kalam S., Sayyed R.Z., Reddy M.S., El Enshasy H. Plant growth promoting rhizobacteria (PGPR) as green bioinoculants: recent development, constraints, and prospects. Sustainability. 2021;13:1140. doi: 10.3390/su13031140. DOI

Bazzaz F.A., Carlson R.W., Rolfe G.L. The effect of heavy metals on plants: Part I. Inhibition of gas exchange in sunflower by Pb, Cd, Ni and Tl. Environ. Pollut. 1974;7:241–246. doi: 10.1016/0013-9327(74)90032-9. DOI

Bencko V. Nickel: a review of its occupational and environmental toxicology. J. Hyg. Epidemiol. Microbiol. Immunol. 1983;27:237. PubMed

Bhutto M.A., Zahida P., Sajid I., Mubarik A., Sahar N. Monitoring of heavy and essential trace metals contents in wheat procured from various countries by the Government of Pakistan in the year 2008–09. Int. J. Biol. Biotechnol. 2009;6:247–250.

Calzado L.E., Gomez C.O., Finch J.A. Nickel recovered from solution by oxidation using ozone: some physical properties. Miner. Eng. 2005;18:537–543. doi: 10.1016/j.mineng.2004.09.003. DOI

Chen C., Huang D., Liu J. Functions and toxicity of nickel in plants: recent advances and future prospects. Clean - Soil, Air, Water. 2009 doi: 10.1002/clen.200800199. DOI

Chen F., Wu F., Dong J., Vincze E., Zhang G., Wang F., Huang Y., Wei K. Cadmium translocation and accumulation in developing barley grains. Planta. 2007;227:223–232. doi: 10.1007/s00425-007-0610-3. PubMed DOI

Cui L., Pan G., Li L., Yan J., Zhang A., Bian R., Chang A. The reduction of wheat Cd uptake in contaminated soil via biochar amendment: a two-year field experiment. Bio Resour. 2012;7:5666–5676.

Cuypers A., Plusquin M., Remans T., Jozefczak M., Keunen E., Gielen H., Opdenakker K., Nair A.R., Munters E., Artois T.J., Nawrot T., Vangronsveld J., Smeets K. Cadmium stress: an oxidative challenge. BioMetals. 2010;23(5):927–940. doi: 10.1007/s10534-010-9329-x. PubMed DOI

Danish S., Kiran S., Fahad S., Ahmad N., Ali M.A., Tahir F.A., Rasheed M.K., Shahzad K., Li X., Wang D., Mubeen M., Abbas S., Munir T.M., Hashmi M.Z., Adnan M., Saeed B., Saud S., Khan M.N., Ullah A., Nasim W. Alleviation of chromium toxicity in maize by Fe fortification and chromium tolerant ACC deaminase producing plant growth promoting rhizobacteria. Ecotoxicol. Environ. Saf. 2019;185 doi: 10.1016/j.ecoenv.2019.109706. PubMed DOI

Danish S., Tahir F.A., Rasheed M.K., Ahmad N., Ali M.A., Kiran S., Younis U., Irshad I., Butt B. Effect of foliar application of Fe and banana peel waste biochar on growth, chlorophyll content and accessory pigments synthesis in spinach under chromium (IV) toxicity. Open Agric. 2019;4:381–390. doi: 10.1515/opag-2019-0034. DOI

Danish S., Younis U., Akhtar N., Ameer A., Ijaz M., Nasreen S., Huma F., Sharif S., Ehsanullah M. Phosphorus solubilizing bacteria and rice straw biochar consequence on maize pigments synthesis. Int. J. Biosci. 2015;5:31–39. doi: 10.12692/ijb/5.12.31-39. DOI

Danish S., Younis U., Nasreen S., Akhtar N., Iqbal M.T. Biochar consequences on cations and anions of sandy soil. J. Biodivers. Environ. Sci. 2015;6:121–131.

Danish S., Zafar-ul-Hye M. Combined role of ACC deaminase producing bacteria and biochar on cereals productivity under drought. Phyton-Int. J. Exp. Bot. 2020;89:217–227. doi: 10.32604/phyton.2020.08523. DOI

Danish S., Zafar-ul-Hye M. Co-application of ACC-deaminase producing PGPR and timber-waste biochar improves pigments formation, growth and yield of wheat under drought stress. Sci. Rep. 2019;9 doi: 10.1038/s41598-019-42374-9. PubMed DOI PMC

Danish S., Zafar-ul-Hye M., Mohsin F., Hussain M. ACC-deaminase producing plant growth promoting rhizobacteria and biochar mitigate adverse effects of drought stress on maize growth. PLoS One. 2020;15 PubMed PMC

Demirbas A. Effects of temperature and particle size on bio-char yield from pyrolysis of agricultural residues. J. Anal. Appl. Pyrolysis. 2004;72:243–248. doi: 10.1016/j.jaap.2004.07.003. DOI

Deng Y., Huang S., Laird D.A., Wang X., Meng Z. Adsorption behaviour and mechanisms of cadmium and nickel on rice straw biochars in single- and binary-metal systems. Chemosphere. 2019;218:308–318. doi: 10.1016/j.chemosphere.2018.11.081. PubMed DOI

Dixit P., Mukherjee P.K., Ramachandran V., Eapen S. Glutathione transferase from Trichoderma virens enhances cadmium tolerance without enhancing its accumulation in transgenic Nicotiana tabacum. PLoS One. 2011;6:16360. doi: 10.1371/journal.pone.0016360. PubMed DOI PMC

Dong J., Wu F., Zhang G. Influence of cadmium on antioxidant capacity and four microelement concentrations in tomato seedlings (Lycopersicon esculentum) Chemosphere. 2006;64:1659–1666. doi: 10.1016/j.chemosphere.2006.01.030. PubMed DOI

Downie A., Crosky A., Munroe P., Crosky A., Munroe P. In: Biochar for Environmental Management: Science and Technology. Lehmann J., Joseph S., editors. Routledge; Earthscan, London: 2012. Physical properties of biochar; pp. 13–32. DOI

Dražić G., Mihailović N., Lojić M. Cadmium accumulation in Medicago sativa seedlings treated with salicylic acid. Biol. Plant. 2006;50:239–244. doi: 10.1007/s10535-006-0013-5. DOI

Dresler S., Wójcik M., Bednarek W., Hanaka A., Tukiendorf A. The effect of silicon on maize growth under cadmium stress. Russ. J. Plant Physiol. 2015;62:86–92. doi: 10.1134/S1021443715010057. DOI

Fiaz K., Danish S., Younis U., Malik S.A., Raza Shah M.H., Niaz S. Drought impact on Pb/Cd toxicity remediated by biochar in Brassica campestris. J. Soil Sci. Plant Nutr. 2014;14:845–854. doi: 10.4067/S0718-95162014005000067. DOI

Gajewska E., Skłodowska M., Słaba M., Mazur J. Effect of nickel on antioxidative enzyme activities, proline and chlorophyll contents in wheat shoots. Biol. Plant. 2006;50:653–659. doi: 10.1007/s10535-006-0102-5. DOI

Genchi G., Sinicropi M.S., Lauria G., Carocci A., Catalano A. The effects of cadmium toxicity. Int. J. Environ. Res. Public Health. 2020 doi: 10.3390/ijerph17113782. PubMed DOI PMC

Gill S.S., Tuteja N. Cadmium stress tolerance in crop plants: probing the role of sulfur. Plant Signal. Behav. 2011 doi: 10.4161/psb.6.2.14880. PubMed DOI PMC

Glaser B. Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century. Philos. Trans. R. Soc. B Biol. Sci. 2007 doi: 10.1098/rstb.2006.1978. PubMed DOI PMC

Greger M., Brammer E., Lindberg S., Larsson G., Idestam-almquist J. Uptake and physiological effects of cadmium in sugar beet (Beta vulgaris) related to mineral provision. J. Exp. Bot. 1991;42:729–737. doi: 10.1093/jxb/42.6.729. DOI

Gupta N., Khan D.K., Santra S.C. Determination of public health hazard potential of wastewater reuse in crop production. World Rev. Sci. Technol. Sustain. Dev. 2010;7:328–340. doi: 10.1504/WRSTSD.2010.032741. DOI

Hasan S.A., Hayat S., Ali B., Ahmad A. 28-Homobrassinolide protects chickpea (Cicer arietinum) from cadmium toxicity by stimulating antioxidants. Environ. Pollut. 2008;151:60–66. doi: 10.1016/j.envpol.2007.03.006. PubMed DOI

Hashmi S., Younis U., Danish S., Munir T.M. Pongamia pinnata L. leaves biochar increased growth and pigments syntheses in Pisum sativum L. exposed to nutritional stress. Agric. 2019;9:153. doi: 10.3390/agriculture9070153. DOI

Hossain M.K., Strezov V., Chan K.Y., Nelson P.F. Agronomic properties of wastewater sludge biochar and bioavailability of metals in production of cherry tomato (Lycopersicon esculentum) Chemosphere. 2010;78:1167–1171. doi: 10.1016/j.chemosphere.2010.01.009. PubMed DOI

Hossny E., Mokhtar G., El-Awady M., Ali I., Morsy M., Dawood A. Environmental exposure of the pediatric age groups in Cairo City and its suburbs to cadmium pollution. Sci. Total Environ. 2001;273:135–146. doi: 10.1016/S0048-9697(00)00848-2. PubMed DOI

Inouhe M. Phytochelatin. Brazilian J. Plant Physiol. 2005;17:65–78.

Irfan M., Hayat S., Ahmad A., Alyemeni M.N. Soil cadmium enrichment: allocation and plant physiological manifestations. Saudi J. Biol. Sci. 2013;20(1):1–10. doi: 10.1016/j.sjbs.2012.11.004. PubMed DOI PMC

Izhar Shafi M., Adnan M., Fahad S., Wahid F., Khan A., Yue Z., Danish S., Zafar-ul-Hye M., Brtnicky M., Datta R. Application of single superphosphate with humic acid improves the growth, yield and phosphorus uptake of wheat (Triticum aestivum L.) in calcareous soil. Agronomy. 2020;10:1224.

Jiang J., Xu R., Jiang T., Li Z. Immobilization of Cu(II), Pb(II) and Cd(II) by the addition of rice straw derived biochar to a simulated polluted Ultisol. J. Hazard. Mater. 2012;229:145–150. doi: 10.1016/j.jhazmat.2012.05.086. PubMed DOI

Kabata-Pendias A. CRC Press; 2011. Trace Elements in Soils and Plants; pp. 1–534. 10.1201/b10158-25.

Khalid B.Y., Tinsley J. Some effects of nickel toxicity on rye grass. Plant Soil. 1980;55:139–144. doi: 10.1007/BF02149717. DOI

Kraska P., Oleszczuk P., Andruszczak S., Kwiecińska-Poppe E., Różyło K., Pałys E., Gierasimiuk P., Michałojć Z. Effect of various biochar rates on winter rye yield and the concentration of available nutrients in the soil. Plant, Soil Environ. 2016;62:483–489. doi: 10.17221/94/2016-PSE. DOI

Krupa Z., Baszynski T. Some aspects of heavy metals toxicity towards photosynthetic apparatus-direct and indirect effects on light and dark reactions. Acta Physiol. Plant. 1995;17:177–190.

Kumar O., Singh S.K., Singh A.P., Yadav S.N., Latare A.M. Effect of soil application of nickel on growth, micronutrient concentration and uptake in barley (Hordeum vulgare L.) grown in Inceptisols of Varanasi. J. Plant Nutr. 2018;41:50–66. doi: 10.1080/01904167.2017.1381724. DOI

Laghari M., Mirjat M.S., Hu Z., Fazal S., Xiao B., Hu M., Chen Z., Guo D. Effects of biochar application rate on sandy desert soil properties and sorghum growth. Catena. 2015;135:313–320. doi: 10.1016/j.catena.2015.08.013. DOI

Larbi A., Morales F., Abadia A., Gogorcena Y., Lucena J.J., Abadia J. Effects of Cd and Pb in sugar beet plants grown in nutrient solution: induced Fe deficiency and growth inhibition. Funct. Plant Biol. 2002;29:1453–1464. doi: 10.1071/FP02090. PubMed DOI

Lasat M.M. Phytoextraction of toxic metals: a review of biological mechanisms. J. Environ. Qual. 2002;31:109–120. PubMed

Lehmann J., Gaunt J., Rondon M. Bio-char sequestration in terrestrial ecosystems – a review. Mitig. Adapt. Strateg. Glob. Chang. 2006;11:395–419.

Liu Y., Lu H., Yang S., Wang Y. Impacts of biochar addition on rice yield and soil properties in a cold waterlogged paddy for two crop seasons. F. Crop. Res. 2016;191:161–167. doi: 10.1016/j.fcr.2016.03.003. DOI

López-Millán A.F., Sagardoy R., Solanas M., Abadía A., Abadía J. Cadmium toxicity in tomato (Lycopersicon esculentum) plants grown in hydroponics. Environ. Exp. Bot. 2009;65:376–385. doi: 10.1016/j.envexpbot.2008.11.010. DOI

Lozano-Rodríguez E., Hernandez L.E., Bonay P., Carpena-Ruiz R.O. Distribution of cadmium in shoot and root tissues of maize and pea plants: physiological disturbances. J. Exp. Bota. 1997;48:123–128.

Lu S.G., Sun F.F., Zong Y.T. Effect of rice husk biochar and coal fly ash on some physical properties of expansive clayey soil (Vertisol) Catena. 2014;114:37–44. doi: 10.1016/j.catena.2013.10.014. DOI

Machida Y.J., Teer J.K., Dutta A. Acute reduction of an origin recognition complex (ORC) subunit in human cells reveals a requirement of ORC for Cdk2 activation. J. Biol. Chem. 2005;280:27624–27630. doi: 10.1074/jbc.M502615200. PubMed DOI

Madhava Rao K.V., Sresty T.V.S. Antioxidative parameters in the seedlings of pigeonpea (Cajanus cajan (L.) Millspaugh) in response to Zn and Ni stresses. Plant Sci. 2000;157:113–128. doi: 10.1016/S0168-9452(00)00273-9. PubMed DOI

Major J. Biochar for soil remediation and land reclamation. IBI Res. Summ. 2011:1–6.

Maksymiec W. Effect of copper on cellular processes in higher plants. Photosynthetica. 1998;34(3):321–342. doi: 10.1023/A:1006818815528. DOI

Mohan D., Pittman C.U., Bricka M., Smith F., Yancey B., Mohammad J., Steele P.H., Alexandre-Franco M.F., Gómez-Serrano V., Gong H. Sorption of arsenic, cadmium, and lead by chars produced from fast pyrolysis of wood and bark during bio-oil production. J. Colloid Interface Sci. 2007;310:57–73. doi: 10.1016/j.jcis.2007.01.020. PubMed DOI

Mohanty N., Vass I., Demeter S. Copper toxicity affects photosystem II electron transport at the secondary quinone acceptor. Q B. Plant Physiol. 1989;90:175–179. doi: 10.1104/pp.90.1.175. PubMed DOI PMC

Molas J. Changes in morphological and anatomical structure of cabbage (Brassica oleracea L.) outer leaves and in ultrastructure of their chloroplasts caused by an in vitro excess of nickel. Photosynthetica. 1998;34:513–522. doi: 10.1023/A:1006805327340. DOI

Nishijo M., Morikawa Y., Nakagawa H., Tawara K., Miura K., Kido T., Ikawa A., Kobayashi E., Nogawa K. Causes of death and renal tubular dysfunction in residents exposed to cadmium in the environment. Occup. Environ. Med. 2006;63:545–550. doi: 10.1136/oem.2006.026591. PubMed DOI PMC

Nordberg G., Jin T., Bernard A., Fierens S., Buchet J.P., Ye T., Kong Q., Wang H. Low bone density and renal dysfunction following environmental cadmium exposure in China. Ambio. 2002;31:478–481. doi: 10.1579/0044-7447-31.6.478. PubMed DOI

Nriagu J.O. A history of global metal pollution. Science. 1996;272(5259):223. doi: 10.1126/science.272.5259.223. DOI

Olowoyo J.O., Okedeyi O.O., Mkolo N.M., Lion G.N., Mdakane S.T.R. Uptake and translocation of heavy metals by medicinal plants growing around a waste dump site in Pretoria, South Africa. South African J. Bot. 2012;78:116–121. doi: 10.1016/j.sajb.2011.05.010. DOI

Ouzounidou G., Moustakas M., Symeonidis L., Karataglis S. Response of wheat seedlings to Ni stress: effects of supplemental calcium. Arch. Environ. Contam. Toxicol. 2006;50:346–352. PubMed

Palacios G., Gómez I., Carbonell-Barrachina A., Navarro Pedreño J., Mataix J. Effect of nickel concentration on tomato plant nutrition and dry matter yield. J. Plant Nutr. 1998;21:2179–2191. doi: 10.1080/01904169809365553. DOI

Pandolfini T., Gabbrielli R., Comparini C. Nickel toxicity and peroxidase activity in seedlings of Triticum aestivum L. Plant. Cell Environ. 1992;15:719–725. doi: 10.1111/j.1365-3040.1992.tb01014.x. DOI

Park J.H., Choppala G.K., Bolan N.S., Chung J.W., Chuasavathi T. Biochar reduces the bioavailability and phytotoxicity of heavy metals. Plant Soil. 2011;348:439.

Pathan S.I., Větrovský T., Giagnoni L., Datta R., Baldrian P., Nannipieri P., Renella G. Microbial expression profiles in the rhizosphere of two maize lines differing in N use efficiency. Plant Soil. 2018;433(1):401–413.

Piccini D.F., Malavolta E. Effect of nickel on two common bean cultivars. J. Plant Nutr. 1992;15:2343–2350.

Pinto A.P., Mota A.M., De Varennes A., Pinto F.C. Influence of organic matter on the uptake of cadmium, zinc, copper and iron by sorghum plants. Sci. Total Environ. 2004;326:239–247. doi: 10.1016/j.scitotenv.2004.01.004. PubMed DOI

Pulford I.D., Watson C. Phytoremediation of heavy metal-contaminated land by trees - A review. Environ. Int. 2003;29(4):529–540. doi: 10.1016/S0160-4120(02)00152-6. PubMed DOI

Quilliam R.S., Glanville H.C., Wade S.C., Jones D.L. Life in the “charosphere” - Does biochar in agricultural soil provide a significant habitat for microorganisms? Soil Biol. Biochem. 2013;65:287–293. doi: 10.1016/j.soilbio.2013.06.004. DOI

Radziemska M., Gusiatin Z.M., Cydzik-Kwiatkowska A., Cerdà A., Pecina V., Bęś A., Datta R., Majewski G., Mazur Z., Dzięcioł J., Danish S., Brtnicky M. Insight into metal immobilization and microbial community structure in soil from a steel disposal dump that was phytostabilized with composted, pyrolyzed or gasified wastes. Chemosphere. 2021;272 doi: 10.1016/j.chemosphere.2021.129576. PubMed DOI

Rafiullah, Tariq, M., Khan, F., Shah, A.H., Fahad, S., Wahid, F., Ali, J., Adnan, M., Ahmad, M., Irfan, M., Zafar-ul-Hye, M., Battaglia, M.L., Zarei, T., Datta, R., Saleem, I.A., Hafeez-u-Rehman, Danish, S., 2020. Effect of micronutrients foliar supplementation on the production and eminence of plum. Qual. Assur. Saf. Crop. Foods 12, 32–40. 10.15586/qas.v12iSP1.793.

Rao K., Mohapatra M., Anand S., Venkateswarlu P. Review on cadmium removal from aqueous solutions. Int. J. Eng. Sci. Technol. 2011;2:81–103. doi: 10.4314/ijest.v2i7.63747. DOI

Reeves R.D., Baker A.J.M. John Wiley and Sons Ltd.; New York: 2000. Metal-accumulating plants. Phytoremediation of Toxic Metals: Using Plants to Clean Up the Environment.

Renner R. Rethinking biochar. Environ. Sci. Technol. 2007:5932–5933. doi: 10.1021/es0726097. PubMed DOI

Rondon, M., Ramirez, A., Hurtado, M., 2004. Charcoal additions to high fertility ditches enhance yields and quality of cash crops in Andean hillsides of Colombia, CIAT Annual Report. Cali, Colombia.

Ruiz J.M., Blasco B., Ríos J.J., Cervilla L.M., Rosales M.A., Rubio-wilhelmi M.M., Sánchez-rodríguez E., Castellano R., Romero L. Distribution and efficiency of the phytoextraction of cadmium by different organic chelates. Terra Latinoam. 2009;27:295–301.

Satarug S., Baker J.R., Urbenjapol S., Haswell-Elkins M., Reilly P.E.B., Williams D.J., Moore M.R. A global perspective on cadmium pollution and toxicity in non-occupationally exposed population. Toxicol. Lett. 2003:65–83. doi: 10.1016/S0378-4274(02)00381-8. PubMed DOI

Satarug S., Garrett S.H., Sens M.A., Sens D.A. Cadmium, environmental exposure, and health outcomes. Environ. Health Perspect. 2010;118(2):182–190. doi: 10.1289/ehp.0901234. PubMed DOI PMC

Scott-Fordsmand J.J. In: Reviews of Environmental Contamination and Toxicology. Ware G.W., Nigg H.N., Bevenue A., editors. Springer; New York, NY: 1997. Toxicity of nickel to soil organisms in Denmark; pp. 1–34. DOI

Seregin I.V., Ivanov V.B. Physiological aspects of cadmium and lead toxic effects on higher plants. Russ. J. Plant Physiol. 2001;48:523–544. doi: 10.1023/A:1016719901147. DOI

Shah K., Nongkynrih J.M. Metal hyperaccumulation and bioremediation. Biol. Plant. 2007;51(4):618–634. doi: 10.1007/s10535-007-0134-5. DOI

Sharma S., Sharma P., Melhotra P. Bioaccumulation of heavy metals in Pisum sativum L. growing in fly ash amended soil. J. Amer. Sci. 2010;6:43–50.

Sheoran I.S., Singal H.R., Singh R. Effect of cadmium and nickel on photosynthesis and the enzymes of the photosynthetic carbon reduction cycle in pigeonpea (Cajanus cajan L.) Photosynth. Res. 1990;23:345–351. doi: 10.1007/BF00034865. PubMed DOI

Sohi S.P., Krull E., Bol R. A review of biochar and its use and function in soil. Adv. Agron. 2010;105:47–82. doi: 10.1016/S0065-2113(10)05002-9. DOI

Sultan H., Ahmed N., Mubashir M., Danish S. Chemical production of acidified activated carbon and its influences on soil fertility comparative to thermo-pyrolyzed biochar. Sci. Rep. 2020;10:595. doi: 10.1038/s41598-020-57535-4. PubMed DOI PMC

Tando, E., Nugroho, A., Islami, T., 2017. Effect of sago waste, manure and straw biochar on peanut (Arachis hypogaea L.) growth and yield on an Ultisol of Southeast Sulawesi. J. Degrad. Min. Lands Manag. 4, 749–757. 10.15243/jdmlm.2017.042.749.

Thies J., Rillig M.C. Biochar for environmental management: Science and technology. Earthscan; London: 2009. Characteristics of biochar: Biological properties.

Tian X., Li C., Zhang M., Wan Y., Xie Z., Chen B., Li W. Biochar derived from corn straw affected availability and distribution of soil nutrients and cotton yield. PLoS One. 2018;13 doi: 10.1371/journal.pone.0189924. PubMed DOI PMC

Tripathy B.C., Bhatia B., Mohanty P. Inactivation of chloroplast photosynthetic electron-transport activity by Ni2+ BBA - Bioenerg. 1981;638:217–224. doi: 10.1016/0005-2728(81)90230-9. DOI

Uchimiya M., Chang S.C., Klasson K.T. Screening biochars for heavy metal retention in soil: role of oxygen functional groups. J. Hazard. Mater. 2011;190:432–441. doi: 10.1016/j.jhazmat.2011.03.063. PubMed DOI

Ullah A., Ali M., Shahzad K., Ahmad F., Iqbal S., Habib M., Rahman U., Ahmad S., Iqbal M.M. Impact of seed dressing and soil application of potassium humate on cotton plants productivity and fiber quality. Plants. 2020;9:1444. doi: 10.3390/plants9111444. PubMed DOI PMC

Van Zwieten L., Kimber S., Morris S., Chan K.Y., Downie A., Rust J., Joseph S., Cowie A. Effects of biochar from slow pyrolysis of papermill waste on agronomic performance and soil fertility. Plant Soil. 2010;327:235–246. doi: 10.1007/s11104-009-0050-x. DOI

Veeranjaneyulu K., Das V.S.R. Intrachloroplast localization of 65Zn and 63Ni in a zn-tolerant plant, Ocimum basilicum benth. J. Exp. Bot. 1982;33:1161–1165. doi: 10.1093/jxb/33.6.1161. DOI

Verheijen F., Jeffery S., Bastos C., Van Der Velde M., Diafas I. Biochar application to soils. A critical scientific review of effects on soil properties, processes and functions. Environment. 2010;8:149. doi: 10.2788/472. DOI

Warnock, D.D., 2009. Arbuscular mycorrhizal responses to biochars in soils - potential mechanisms of interaction and observed responses in controlled environments. Division of Biological Sciences and the Microbial Ecology and Department of Crop and Soil Sciences. University of Montana and Cornell University.

Woods, W.I., Denevan, W.M., 2009. Amazonian dark earths: The first century of reports. In: Teixeira, W.I., Lehmann, W.G., Steiner, J., WinklerPrins, C., Rebellato, L. (Eds.), Amazonian Dark Earths: Wim Sombroek’s Vision. Springer, Dordrecht, pp. 1–14. 10.1007/978-1-4020-9031-8_1

Woolf D., Amonette J.E., Street-Perrott F.A., Lehmann J., Joseph S. Sustainable biochar to mitigate global climate change. Nat. Commun. 2010;1:56. PubMed PMC

Yadav S.S., Shukla R., Sharma Y.K. Nickel toxicity on seed germination and growth in radish (Raphanus sativus) and its recovery using copper and boron. J. Environ. Biol. 2009;30:461–466. PubMed

Younis U., Qayyum M.F., Shah M.H.R., Danish S., Shahzad A.N., Malik S.A., Mahmood S. Growth, survival, and heavy metal (Cd and Ni) uptake of spinach (Spinacia oleracea) and fenugreek (Trigonella corniculata) in a biochar-amended sewage-irrigated contaminated soil. J. Plant Nutr. Soil Sci. 2015;178:209–217. doi: 10.1002/jpln.201400325. DOI

Zafar-ul-Hye M., Danish S., Abbas M., Ahmad M., Munir T.M. ACC deaminase producing PGPR Bacillus amyloliquefaciens and agrobacterium fabrum along with biochar improve wheat productivity under drought stress. Agronomy. 2019;9:343. doi: 10.3390/agronomy9070343. DOI

Zafar-ul-Hye M., Naeem M., Danish S., Fahad S., Datta R., Abbas M., Rahi A.A., Brtnicky M., Holátko J., Tarar Z.H., Nasir M. Alleviation of cadmium adverse effects by improving nutrients uptake in bitter gourd through cadmium tolerant rhizobacteria. Environments. 2020;7:54. doi: 10.3390/environments7080054. DOI

Zafar-ul-Hye M., Naeem M., Danish S., Khan M.J., Fahad S., Datta R., Brtnicky M., Kintl A., Hussain G.S., El-Esawi M.A. Effect of cadmium-tolerant rhizobacteria on growth attributes and chlorophyll contents of bitter gourd under cadmium toxicity. Plants. 2020;9:1386. doi: 10.3390/plants9101386. PubMed DOI PMC

Zafar-ul-Hye M., Naeem M., Danish S., Khan M.J., Fahad S., Datta R., Brtnicky M., Kintl A., Hussain M.S., El-esawi M.A. Effect of cadmium-tolerant rhizobacteria on growth attributes and chlorophyll contents of bitter gourd under cadmium toxicity. Plants. 2020;9 doi: 10.3390/plants9101386. PubMed DOI PMC

Zafar-ul-Hye M., Tahzeeb-ul-Hassan M., Abid M., Fahad S., Brtnicky M., Dokulilova T., Datta R., Danish S. Potential role of compost mixed biochar with rhizobacteria in mitigating lead toxicity in spinach. Sci. Rep. 2020;10:1–12. PubMed PMC

Sustainable remediation of chromium-contaminated soils: boosting radish growth with deashed biochar and strigolactone