Application of Rice Husk Biochar for Achieving Sustainable Agriculture and Environment

doi:10.1016/j.rsci.2021.05.004

Abstract

Abstract:

This paper critically reviewed the current knowledge and challenges of rice husk biochar (RHB) production and its effects on soil properties, plant growth, immobilization of heavy metals, reduction of nutrient leaching and mitigation of greenhouse gas emissions. The characteristics of RHBs produced at various pyrolysis temperatures were discussed and compared to biochars derived from other agro- industrial wastes. RHBs produced at higher pyrolysis temperatures show lower hydrogen/carbon ratio, which suggests the presence of higher aromatic carbon compounds. The increase of pyrolysis temperature also results in production of RHBs with higher ash content, lower yield and higher surface area. RHB usually has higher silicon and ash contents and lower carbon content compared to biochars derived from other feedstocks at the same pyrolysis conditions. Although it depends on soil type, RHB application can improve soil organic carbon content, cation exchange capacity, available K concentration, bulk density and microbial activity. The effect of RHB on soil aggregation mainly depends on soil texture. The growth of different crops is also enhanced by application of RHB. RHB addition to soil can immobilize heavy metals and herbicides and reduce their bioavailability. RHB application shows a significant capacity in reduction of nitrate leaching, although its magnitude depends on the biochar application rate and soil biogeochemical characteristics. Use of RHB, especially in paddy fields, shows a promising mitigation effect on greenhouse gas (CH₄, CO₂ and N₂O) emissions. Although RHB characteristics are also related to other factors such as pyrolysis heating rate and residence time, its performance for specific applications (e.g. carbon sequestration, pH amendment) can be manipulated by adjusting the pyrolysis temperature. More research is needed on long-term field applications of RHB to fully understand the advantages and disadvantages of RHB as a soil amendment.

Key words: carbon sequestration, crop production, greenhouse gas, heavy metal, nitrogen leaching, soil amendment, rice husk biochar

Asadi Hossein, Ghorbani Mohammad, Rezaei-Rashti Mehran, Abrishamkesh Sepideh, Amirahmadi Elnaz, Chengrong Chen, Gorji Manouchehr. Application of Rice Husk Biochar for Achieving Sustainable Agriculture and Environment[J]. Rice Science, 2021, 28(4): 325-343.

Figures/Tables 11

References 139

[1]	Abbas T, Rizwan M, Ali S, Adrees M, Mahmood A, Zia-ur-Rehman M, Ibrahim M, Arshad M, Qayyum M F. 2018. Biochar application increased the growth and yield and reduced cadmium in drought stressed wheat grown in an aged contaminated soil. Ecotox Environ Safe, 148: 825‒833.
[2]	Abrishamkesh S, Gorji M, Asadi H, Bagheri-Marandi G H, Pourbabaei A A. 2015. Effects of rice husk biochar application on the properties of alkaline soil and lentil growth. Plant Soil Environ, 61(11): 475-482.
[3]	Abrishamkesh S, Gorji M, Asadi H, Pourbabaei A A, Bagheri- Marandi G H. 2017. Production of rice husk biochar and its effects on lentil and wheat biomass. Soil Manag Sustain Product, 7(2): 135‒150. (in Persian with English abstract)
[4]	Ahmad M, Lee S S, Dou X M, Mohan D, Sung J K, Yang J E, Ok Y S. 2012. Effects of pyrolysis temperature on soybean stover- and peanut shell-derived biochar properties and TCE adsorption in water. Biores Technol, 118: 536‒544.
[5]	Ahmad M, Rajapaksha A U, Lim J E, Zhang M, Bolan N, Mohan D, Vithanage M, Lee S S, Ok Y S. 2014. Biochar as a sorbent for contaminant management in soil and water: A review. Chemosphere, 99: 19‒33.
[6]	Ajayi A E, Horn R. 2017. Biochar-induced changes in soil resilience: Effects of soil texture and biochar dosage. Pedosphere, 27(2): 236-247.
[7]	Alaboudi K A, Ahmed B, Brodie G. 2019. Effect of biochar on Pb, Cd and Cr availability and maize growth in artificial contaminated soil. Ann Agric Sci, 64(1): 95-102.
[8]	Alobwede E, Leake J R, Pandhal J. 2019. Circular economy fertilization: Testing micro and macro algal species as soil improvers and nutrient sources for crop production in greenhouse and field conditions. Geoderma, 334: 113‒123.‏
[9]	Amirahmadi E, Mohammad H S, Kammann C, Ghorbani M, Biparva P. 2020. The potential effectiveness of biochar application to reduce soil Cd bioavailability and encourage oak seedling growth. Appl Sci, 10(10): 3410.
[10]	Bharadwaj A, Wang Y, Sridhar S, Arunachalam V S. 2004. Pyrolysis of rice husk. Curr Sci, 87(7): 981-986.
[11]	Bodie A R, Micciche A C, Atungulu G G, Rothrock Jr M J, Ricke S C. 2019. Current trends of rice milling byproducts for agricultural applications and alternative food production systems. Front Sustain Food Syst, 3: 47.
[12]	Borchard N, Schirrmann M, Cayuela M L, Kammann C, Wrage- Mönnig N, Estavillo J M, Fuertes-Mendizábal T, Sigua G, Spokas K, Ippolito J A, Novak J. 2019. Biochar, soil and land-use interactions that reduce nitrate leaching and N2O emissions: A meta-analysis. Sci Total Environ, 651: 2354‒2364.
[13]	Bu X L, Xue J H, Zhao C X, Wu Y B, Han F Y. 2017. Nutrient leaching and retention in riparian soils as influenced by rice husk biochar addition. Soil Sci, 182(7): 241-247.
[14]	Bu X L, Su J, Xue J H, Wu Y B, Zhao C X, Wang L M. 2019. Effect of rice husk biochar addition on nutrient leaching and microbial properties of calcaric cambisols. J Soils Water Conserv, 74(2): 172-179.
[15]	Bünemann E K, Bongiorno G, Bai Z, Creamer R E, De Deyn G, de Goede R, Fleskens L, Geissen V, Kuyper T W, Mäder P, Pulleman M. 2018. Soil quality: A critical review. Soil Biol Biochem, 120: 105‒125.
[16]	Cao X D, Ma L N, Gao B, Harris W. 2009. Dairy-manure derived biochar effectively sorbs lead and atrazine. Environ Sci Technol, 43(9): 3285-3291. ‏
[17]	Cao Y N, Yang B S, Song Z H, Wang H, He F, Han X M. 2016. Wheat straw biochar amendments on the removal of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. Ecotoxicol Environ Saf, 130: 248‒255.
[18]	Chaplot V, Cooper M. 2015. Soil aggregate stability to predict organic carbon outputs from soils. Geoderma, 243: 205‒213.
[19]	Chen D, Liu X Y, Bian R J, Cheng K, Zhang X H, Zheng J F, Joseph S, Crowley D, Pan G X, Li L Q. 2018. Effects of biochar on availability and plant uptake of heavy metals: A meta- analysis. J Environ Manage, 222: 76‒85. ‏
[20]	Crombie K, Mašek O, Sohi S P, Brownsort P, Cross A. 2013. The effect of pyrolysis conditions on biochar stability as determined by three methods. GCB Bioenergy, 5(2): 122-131.
[21]	Cui Y F, Meng J, Wang Q X, Zhang W M, Cheng X Y, Chen W F. 2017. Effects of straw and biochar addition on soil nitrogen, carbon, and super rice yield in cold waterlogged paddy soils of North China. J Integr Agric, 16(5): 1064-1074.
[22]	Dai Y J, Zhang N X, Xing C M, Cui Q X, Sun Q Y. 2019. The adsorption, regeneration and engineering applications of biocharfor removal organic pollutants: A review. Chemosphere, 223: 12‒27.
[23]	de Sousa A M B, Santos R R S, Gehring C. 2014. Charcoal in Amazonian paddy soil-nutrient availability, rice growth and methane emissions. J Plant Nutr Soil Sc, 177(1): 39-47.
[24]	Ding Y, Liu Y X, Wu W X, Shi D Z, Yang M, Zhong Z K. 2010. Evaluation of biochar effects on nitrogen retention and leaching in multi-layered soil columns. Water Air Soil Poll, 213: 47‒55.
[25]	Dong D, Feng Q B, McGrouther K, Yang M, Wang H L, Wu W X. 2015. Effects of biochar amendment on rice growth and nitrogen retention in a waterlogged paddy field. J Soils Sediments, 15(1): 153-162.
[26]	Dong X L, Li G T, Lin Q M, Zhao X R. 2017. Quantity and quality changes of biochar aged for 5 years in soil under field conditions. Catena, 159: 136‒143.
[27]	Eduah J O, Nartey E K, Abekoe M K, Breuning-Madsen H, Andersen M N. 2019. Phosphorus retention and availability in three contrasting soils amended with rice husk and corn cob biochar at varying pyrolysis temperatures. Geoderma, 341: 10‒17.
[28]	Enders A, Hanley K, Whitman T, Joseph S, Lehmann J. 2012. Characterization of biochars to evaluate recalcitrance and agronomic performance. Biores Technol, 114: 644-653.
[29]	Farneselli M, Benincasa P, Tosti G, Simonne E, Guiducci M, Tei F. 2015. High fertigation frequency improves nitrogen uptake and crop performance in processing tomato grown with high nitrogen and water supply. Agric Water Manage, 154: 52-58.
[30]	Fazeli Sangani M, Abrishamkesh S, Owens G. 2020. Physico- chemical characteristics of biochars can be beneficially manipulated using post-pyrolyzed particle size modification. Bioresour Technol, 306: 123157.
[31]	Feng Y F, Sun H J, Xue L H, Liu Y, Gao Q, Lu K P, Yang L Z. 2017. Biochar applied at an appropriate rate can avoid increasing NH3 volatilization dramatically in rice paddy soil. Chemosphere, 168: 1277-1284.
[32]	Gamage D V, Mapa R B, Dharmakeerthi R S, Biswas A. 2016. Effect of rice-husk biochar on selected soil properties in tropical Alfisols. Soil Res, 54(3): 302-310.
[33]	Ghorbani M, Asadi H, Abrishamkesh S. 2016. Effect of rice husk biochar on nitrate leaching in a clayey soil. Iran J Soil Res, 29(4): 127‒434. (in Persian with English abstract)
[34]	Ghorbani M, Amirahmadi E. 2018a. Effect of rice husk biochar (RHB) on some of chemical properties of an acidic soil and the absorption of some nutrients. J Appl Sci Environ Manage, 22(3): 313-317.
[35]	Ghorbani M, Amirahmadi E. 2018b. Effect of rice husk biochar on some physical characteristics of soil and corn growth in a loamy soil. Iran J Soil Res, 32(3): 305‒318. (in Persian with English abstract)
[36]	Ghorbani M, Asadi H, Abrishamkesh S. 2019. Effects of rice husk biochar on selected soil properties and nitrate leaching in loamy sand and clay soil. Int Soil Water Conse Res, 7(3): 258-265.
[37]	Graber E R, Tsechansky L, Gerstl Z, Lew B. 2012. High surface area biochar negatively impacts herbicide efficacy. Plant Soil, 353: 95-106.
[38]	Haefele S M, Knoblauch C, Gummert M, Konboon Y, Koyama S. 2008. Black carbon (biochar) in rice-based systems: Characteristics and opportunities. In: Woods W I, Teixeira W G, Lehmann J, Steiner C, Winkler P A, Rebellato L. Amazonian Dark Earths: Wim Sombroek’s Vision. Springer, Netherlands: 445‒463.
[39]	Haefele S M, Konboon Y, Wongboon W, Amarante S, Maarifat A A, Pfeiffer E M, Knoblauch C. 2011. Effects and fate of biochar from rice residues in rice-based systems. Field Crops Res, 121(3): 430-440.
[40]	Huang M, Fan L, Chen J N, Jiang L G, Zou Y B. 2018. Continuous applications of biochar to rice: Effects on nitrogen uptake and utilization. Sci Rep, 8(1): 11461.
[41]	Huang M, Fan L, Jiang L G, Yang S Y, Zou Y B, Uphoff N. 2019. Continuous applications of biochar to rice: Effects on grain yield and yield attributes. J Integr Agric, 18(3): 563-570.
[42]	Huang Z Q, Hu L C, Zhou Q, Tang W, Guo Y, Dai J Y. 2017. Effect of aging on surface chemistry of rice husk-derived biochar. Environ Prog Sustain, 37(1): 410-417.
[43]	Hutchings N, Amon B, Dammgen U, Webb J. 2009. Animal Husbandry and Manure Management. Air Pollutant Emission Inventory Guide Book, Chapter 4B. Copenhagen: European Environmental Agency.
[44]	Ippolito J A, Laird D A, Busscher W J. 2012. Environmental benefits of biochar. J Environ Qual, 41(4): 967-972.
[45]	Jeffery S, Verheijen F G A, van der Velde M, Bastos A C. 2011. A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agric Ecosyst Environ, 144(1): 175-187.
[46]	Jiang J, Xu R K, Jiang T Y, Li Z. 2012. 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, 229: 145-150. ‏
[47]	Jiang T Y, Jiang J, Xu R K, Li Z. 2012. Adsorption of Pb(II) on variable charge soils amended with rice-straw derived biochar. Chemosphere, 89(3): 249-256.
[48]	Jien S H, Wang C S. 2013. Effects of biochar on soil properties and erosion potential in a highly weathered soil. Catena, 110: 225-233.
[49]	Jing X, Wang T F, Yang J L, Wang Y L, Xu H F. 2018. Effects of biochar on the fate and toxicity of herbicide fenoxaprop-ethylin soil. Royal Soc Open Sci, 5(5): 171875.
[50]	Juriga M, Šimanský V, Horák J, Kondrlová E, Igaz D, Polláková N, Buchkina N, Balashov E. 2018. The effect of different rates of biochar and biochar in combination with N fertilizer on the parameters of soil organic matter and soil structure. J Ecol Eng, 19(6): 153-161.
[51]	Khorram M S, Zhang Q, Lin D L, Zheng Y, Fang H, Yu Y L. 2016. Biochar: A review of its impact on pesticide behavior in soil environments and its potential applications. J Environ Sci, 44: 269-279.
[52]	Kizito S, Wu S B, Kipkemoi-Kirui W, Lei M, Lu Q M, Bah H, Dong R J. 2015. Evaluation of slow pyrolyzed wood and rice husks biochar for adsorption of ammonium nitrogen from piggery manure anaerobic digestate slurry. Sci Total Environ, 505: 102-112.
[53]	Kögel-Knabner I, Amelung W, Cao Z H, Fiedler S, Frenzel P, Jahn R, Kalbitz K, Kölbl A, Schloter M. 2010. Biogeochemistry of paddy soils. Geoderma, 157: 1-14.
[54]	Koyama S, Karagiri T, Mninamikawa K, Kato M, Hayash H. 2016. Effects of rice husk charcoal application on rice yield, methane emission, and soil carbon sequestration in andosol paddy soil. Jpn Agric Res Q, 50(4): 319-327.
[55]	Kumar A, Joseph S, Tsechansky L, Privat K, Schreiter I J, Schüth C, Graber E R. 2018. Biochar aging in contaminated soil promotes Zn immobilization due to changes in biochar surface structural and chemical properties. Sci Total Environ, 626: 953-961.
[56]	Kumar M, Rajput T B S, Kumar R, Patel N. 2016. Water and nitrate dynamics in baby corn (Zea mays L.) under different fertigation frequencies and operating pressures in semi-arid region of India. Agric Water Manage, 163: 263-274.
[57]	Kumari K, Prasad J, Solanki I S, Chaudhary R. 2018. Long-term effect of crop residues incorporation on yield and soil physical properties under rice-wheat cropping system in calcareous soil. J Soil Sci Plant Nutr, 18(1): 27-40.
[58]	Lashari M S, Ye Y X, Ji H S, Li L Q, Kibue G W, Lu H F, Zheng J F, Pan G X. 2015. Biochar-manure compost in conjunction with pyroligneous solution alleviated maize salt stress and improved growth in a salt affected soil from Central China: A two-year field experiment. J Sci Food Agric, 95: 1321-1327.
[59]	Laungani R, Elgersma K, McElligott K, Juarez M, Kuhfahl T. 2016. Biochar amendment of grassland soil may promote woody encroachment by Eastern Red Cedar. J Soil Sci Plant Nut, 16(4): 941-954.
[60]	Lehmann J, Rillig M C, Thies J, Masiello C A, Hockaday W C, Crowley D. 2011. Biochar effects on soil biota: A review. Soil Biol Biochem, 43(9): 1812-1836.
[61]	Leng L J, Huang H J. 2018. An overview of the effect of pyrolysis process parameters on biochar stability. Biores Technol, 270: 627-642.
[62]	Li H B, Dong X L, da Silva E B, de Oliveira L M, Chen Y S, Ma L Q. 2017. Mechanisms of metal sorption by biochars: Biochar characteristics and modifications. Chemosphere, 178: 466-478.
[63]	Li S L, Zhang Y W, Yan W M, Shangguan Z P. 2018. Effect of biochar application method on nitrogen leaching and hydraulic conductivity in a silty clay soil. Soil Till Res, 183: 100-108.
[64]	Liu C Y, Jiang X, Ma Y C, Cade-Menun B J. 2017. Pollutant and soil types influence effectiveness of soil-applied absorbents in reducing rice plant uptake of persistent organic pollutants. Pedosphere, 27(3): 537-547.
[65]	Liu S N, Meng J, Jiang L L, Yang X, Lan Y, Cheng X Y, Chen W F. 2017. Rice husk biochar impacts soil phosphorous availability, phosphatase activities and bacterial community characteristics in three different soil types. Appl Soil Ecol, 116: 12-22.
[66]	Liu Z Q, He T Y, Cao T, Yang T X, Meng J, Chen W F. 2017. Effects of biochar application on nitrogen leaching, ammonia volatilization and nitrogen use efficiency in two distinct soils. J Soil Sci Plant Nutr, 17(2): 515-528.
[67]	Lončarić Z, Karalić K, Popović B, Rastija D, Vukobratović M. 2008. Total and plant available micronutrients in acidic and calcareous soils in Croatia. Cereal Res Commun, 36: 331-334.
[68]	Mandal K G, Misra A K, Hati K M, Bandyopadhyay K K, Ghosh P K, Mohanty M. 2004. Rice residue-management options and effects on soil properties and crop productivity. J Food Agric Environ, 2(1): 224-231.
[69]	Manolikaki I, Diamadopoulos E. 2017. Ryegrass yield and nutrient status after biochar application in two Mediterranean soils. Arch Agron Soil Sci, 63(8): 1093-1107.
[70]	Masulili A, Utomo W H, Syechfani M. 2010. Rice husk biochar for rice based cropping system in acid soil. 1: The characteristics of rice husk biochar and its influence on the properties of acid sulfate soils and rice growth in West Kalimantan, Indonesia. J Agric Sci, 2(1): 39-47.
[71]	Mehmood K, Baquy M A A, Xu R K. 2018. Influence of nitrogen fertilizer forms and crop straw biochars on soil exchange properties and maize growth on an acidic Ultisol. Arch Agron Soil Sci, 64(6): 834-849.
[72]	Monaco S, Sacco D, Pelissetti S, Dinuccio E, Balsari P, Rostami M, Grignani C. 2012. Laboratory assessment of ammonia emission after soil application of treated and untreated manures. J Agric Sci, 150(1): 65-73.
[73]	Munda S, Nayak A K, Mishra P N, Bhattacharyya P, Mohanty S, Kumar A, Kumar U, Baig M J, Tripathi R, Shahid M, Adak T, Thilagam V K. 2016. Combined application of rice husk biochar and fly ash improved the yield of lowland rice. Soil Res, 54: 451-459.
[74]	Naeem M A, Khalid M, Aon M, Abbas G, Tahir M, Amjad M, Murtaza B, Yang A Z, Akhtar S S. 2017. Effect of wheat and rice straw biochar produced at different temperatures on maize growth and nutrient dynamics of a calcareous soil. Arch Agron Soil Sci, 63(14): 2048‒2061.
[75]	Nag S K, Kookana R, Smith L, Krull E, Macdonald L M, Gill G. 2011. Poor efficacy of herbicides in biochar-amended soils as affected by their chemistry and mode of action. Chemosphere, 84(11): 1572-1577.
[76]	Nakhli, S A A, Delkash M, Bakhshayesh B E, Kazemian H. 2017. Application of zeolites for sustainable agriculture: A review on water and nutrient retention. Water Air Soil Pollut, 228: 464.
[77]	Nwajiaku I M, Olanrewaju J S, Sato K, Tokunari T, Kitano S, Masunaga T. 2018. Change in nutrient composition of biochar from rice husk and sugarcane bagasse at varying pyrolytic temperatures. Inter J Recycl Organ Waste Agric, 7: 269-276.
[78]	Oertel C, Matschullat J, Zurba K, Zimmermann F, Erasmi S. 2016. Greenhouse gas emissions from soils: A review. Geochemistry, 76(3): 327-352.
[79]	Oladele S O. 2019. Changes in physicochemical properties and quality index of an Alfisol after three years of rice husk biochar amendment in rainfed rice-maize cropping sequence. Geoderma, 353: 359-371.
[80]	Oni B A, Oziegbe O, Olawole O O. 2020. Significance of biochar application to the environment and economy. Ann Agric Sci, 64(2): 222-236.
[81]	Pandian K, Subramaniayan P, Gnasekaran P, Chitraputhirapillai S. 2016. Effect of biochar amendment on soil physical, chemical and biological properties and groundnut yield in rainfed Alfisol of semi-arid tropics. Arch Agron Soil Sci, 62(9): 1293-1310.
[82]	Park J H, Choppala G H, Bolan N S, Chung J W, Chuasavathi T. 2011. Biochar reduces the bioavailability and phytotoxicity of heavy metals. Plant Soil, 348: 439-451.
[83]	Phuong H T, Uddin M A, Kato Y. 2015. Characterization of biochar from pyrolysis of rice husk and rice straw. J Biobased Mater Biol, 9(4): 439-446.
[84]	Pode R. 2016. Potential applications of rice husk ash waste from rice husk biomass power plant. Renewable Sustainable Energy Rev, 53: 1468-1485.
[85]	Ponamperuma F N. 1982. Straw as source nutrient for wetland rice. In: Banta S, Mendoza C V. Organic Matter and Rice. Los Baños, the Philippines: International Rice Research Institute: 117‒136.
[86]	Prapagdee S, Piyatiratitivorakul S, Petsom A. 2016. Physico- chemical activation on rice husk biochar for enhancing of cadmium removal from aqueous solution. Asian J Water Environ Pollut, 13(1): 27-34.
[87]	Pratiwi E P A, Shinogi Y. 2016. Rice husk biochar application to paddy soil and its effects on soil physical properties, plant growth, and methane emission. Paddy Water Environ, 14(4): 521-532.
[88]	Pratiwi E P A, Hillary A K, Fukuda T, Shinogi Y. 2016. The effects of rice husk char on ammonium, nitrate and phosphate retention and leaching in loamy soil. Geoderma, 277: 61-68.
[89]	Purakayastha T J, Das K C, Gaskin J, Harris K, Smith J L, Kumari S. 2016. Effect of pyrolysis temperatures on stability and priming effects of C3 and C4 biochar applied to two different soils. Soil Till Res, 155: 107-115.
[90]	Rajapaksha A U, Vithanage M, Ahmad M, Seo D C, Cho J S, Lee S E, Lee S S, Ok Y S. 2015. Enhanced sulfamethazine removal by steam-activated invasive plant-derived biochar. J Hazard Mater, 290: 43-50.
[91]	Rajkovich S, Enders A, Hanley K, Hyland C, Zimmerman A R, Lehmann J. 2012. Corn growth and nitrogen nutrition after additions of biochars with varying properties to a temperate soil. Biol Fert Soils, 48(3): 271-284.
[92]	Ramzani P M A, Coyne M S, Anjum S, Khan W U D, Iqbal M. 2017. In situ immobilization of Cd by organic amendments and their effect on antioxidant enzyme defense mechanism in mung bean (Vigna radiata L.) seedlings. Plant Physiol Biochem, 118: 561-570. ‏
[93]	Reibe K, Christina-Luise R, Ellmer F. 2015. Hydro-/Biochar application to sandy soils: Impact on yield components and nutrients of spring wheat in pots. Arch Agron Soil Sci, 61(8): 1055-1060.
[94]	Reichel R, Wei J, Islam M S, Schmid C, Wissel H, Schröder P, Schloter M, Brüggemann N. 2019. Potential of wheat straw, spruce sawdust, and lignin as high organic carbon soil amendments to improve agricultural nitrogen use efficiency and retention capacity. Front Plant Sci, 9: 900.
[95]	Rodríguez-Vila A, Asensio V, Forján R, Covelo E F. 2015. Chemical fractionation of Cu, Ni, Pb and Zn in a mine soil amended with compost and biochar and vegetated with Brassica juncea L. J Geochem Explor, 158: 74-81. ‏
[96]	Rostamian R, Heidarpour M, Mousavi S F, Afyuni M. 2015. Characterization and sodium sorption capacity of biochar and activated carbon prepared from rice husk. J Agric Sci Technol, 17(4): 1057-1069.
[97]	Samsuri A W, Sadegh-Zadeh F, Seh-Bardan B J. 2013. Adsorption of As(III) and As(V) by Fe coated biochars and biochars produced from empty fruit bunch and rice husk. J Environ Chem Eng, 1(4): 981-988.
[98]	Scheller E, Joergensen R G. 2008. Decomposition of wheat straw differing in nitrogen content in soils under conventional and organic farming management. J Plant Nutr Soil Sci, 171(6): 886-892.
[99]	Schmidt H P, Pandit B H, Martinsen V, Cornelissen G, Conte P, Kammann C I. 2015. Fourfold increase in pumpkin yield in response to low-dosage root zone application of urine-enhanced biochar to a fertile tropical soil. Agriculture, 5(3): 723-741.
[100]	Shackley S, Carter S, Knowles T, Middelink E, Haefele S, Sohi S, Cross A, Haszeldine S. 2012. Sustainable gasification-biochar systems? A case-study of rice-husk gasification in Cambodia. Part I: Context, chemical properties, environmental and health and safety issues. Energy Policy, 42: 49-58.
[101]	Shinogi Y, Kanri Y. 2003. Pyrolysis of plant, animal and human waste: Physical and chemical characterization of the pyrolytic products. Biores Technol, 90(3): 241-247.
[102]	Singh C, Tiwari S, Gupta V K, Singh J S. 2018. The effect of rice husk biochar on soil nutrient status, microbial biomass and paddy productivity of nutrient poor agriculture soils. Catena, 171: 485-493.
[103]	Singh Mavi M, Singh G, Singh B P, Singh Sekhon B, Choudhary O P, Sagi S, Berry R. 2018. Interactive effects of rice-residue biochar and N-fertilizer on soil functions and crop biomass in contrasting soils. J Soil Sci Plant Nutr, 18(1): 41-59.
[104]	Singh Y, Sidhu H S. 2014. Management of cereal crop residues for sustainable rice-wheat production system in the Indo-Gangetic plains of India. Proc India Nat Sci Acad, 80(1): 95-114.
[105]	Smith P, Martino D, Cai Z, Gwary D, Janzen H, Kumar P, McCarl B, Ogle S, O’Mara F, Rice C, Scholes B, Sirotenko O. 2007. Agriculture. In: Metz B, Davidson O R, Bosch P R, Dave R, Meyer L A. Climate Change 2007: Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York, USA: Cambridge University Press.
[106]	Sohi S P, Krull E, Lopez-Capel E, Bol R. 2010. A review of biochar and its use and function in soil. Adv Agron, 105: 47-82.
[107]	Spokas K A. 2010. Review of the stability of biochar in soils: Predictability of O:C molar ratios. Carbon Manage, 1(2): 289-303.
[108]	Suliman W, Harsh J B, Abu-Lail N I, Fortuna A M, Dallmeyer I, Garcia-Perez M. 2016. Influence of feedstock source and pyrolysis temperature on biochar bulk and surface properties. Biomass Bioenergy, 84: 37‒48.
[109]	Taghizadeh-Toosi A, Clough T J, Sherlock R R, Condron L M. 2012. Biochar adsorbed ammonia is bioavailable. Plant Soil, 350: 57-69.
[110]	Tan X F, Liu Y G, Zeng G M, Wang X, Hu X J, Gu Y L, Yang Z Z. 2015. Application of biochar for the removal of pollutants from aqueous solutions. Chemosphere, 125: 70-85.
[111]	Tryon E H. 1948. Effect of charcoal on certain physical, chemical and biological properties of forest soils. Ecol Monogr, 18(1): 81-115.
[112]	Tsai C C, Chang Y F. 2020. Effects of rice husk biochar on carbon release and nutrient availability in three cultivation age of greenhouse soils. Agronomy, 10(7): 990.
[113]	Uchimiya M, Lima I M, Klasson K T, Wartelle L H. 2010. Contaminant immobilization and nutrient release by biochar soil amendment: Roles of natural organic matter. Chemosphere, 80(8): 935-940.
[114]	Uchimiya M, Wartelle L H, Klasson K T, Fortier C A, Lima I M. 2011. Influence of pyrolysis temperature on biochar property and function as a heavy metal sorbent in soil. J Agric Food Chem, 59(6): 2501-2510.
[115]	Uchimiya M, Bannon D I, Wartelle L H, Lima I M, Klasson K T. 2012. Lead retention by broiler litter biochars in small arms range soil: Impact of pyrolysis temperature. J Agric Food Chem, 60(20): 5035-5044. ‏
[116]	Varela Milla O, Rivera E B, Huang W J, Chien C, Wang Y M. 2013. Agronomic properties and characterization of rice husk and wood biochars and their effect on the growth of water spinach in a field test. J Soil Sci Plant Nutr, 13(2): 251-266.
[117]	Wang L, Wang Y J, Ma F, Tankpa V, Bai S S, Guo X M, Wang X. 2019. Mechanisms and reutilization of modified biochar used for removal of heavy metals from wastewater: A review. Sci Total Environ, 668: 1298-1309.
[118]	Wang Y D, Wang Z L, Zhang Q Z, Hu N, Li Z F, Lou Y L, Li Y, Xue D M, Chen Y, Wu C Y, Zou C B, Kuzyakov Y. 2018. Long-term effects of nitrogen fertilization on aggregation and localization of carbon, nitrogen and microbial activities in soil. Sci Total Environ, 624: 1131-1139.
[119]	Wassmann R, Neue H U, Bueno C, Lantin R S, Alberto M C R, Buendia L V, Bronson K, Papen H, Rennenberg H. 1998. Methane production capacities of different rice soils derived from inherent and exogenous substrates. Plant Soil, 203(2): 227-237.
[120]	Wei L, Huang Y F, Li Y L, Huang L X, Mar N N, Huang Q, Liu Z Z. 2017. Biochar characteristics produced from rice husks and their sorption properties for the acetanilide herbicide metolachlor. Environ Sci Pollut Res Int, 24(5): 4552-4561.
[121]	Weil R R, Brady N C. 2016. The Nature and Properties of Soils. 15th Edition, Upper Saddle River, N.J., Prentice Hall.
[122]	Williams M A, Morse M D, Buckman J F. 1972. Burning vs incorporation of rice crop residues. Agron J, 64(4): 467-468.
[123]	Win K T, Okazaki K, Ookawa T, Yokoyama T, Ohwaki Y. 2019. Influence of rice-husk biochar and Bacillus pumilus strain TUAT-1 on yield, biomass production, and nutrient uptake in two forage rice genotypes. PLoS One, 14(7): 0220236.
[124]	Wu S W, Zhang Y, Tan Q L, Sun X C, Wei W H, Hu C X. 2020. Biochar is superior to lime in improving acidic soil properties and fruit quality of Satsuma mandarin. Sci Total Environ, 714: 136722.
[125]	Xiao X, Chen Z M, Chen B L. 2016. H/C atomic ratio as a smart linkage between pyrolytic temperatures, aromatic clusters and sorption properties of biochars derived from diverse precursory materials. Sci Rep, 6: 22644.
[126]	Xu X Y, Cao X D, Zhao L. 2013. Comparison of rice husk- and dairy manure-derived biochars for simultaneously removing heavy metals from aqueous solutions: Role of mineral components in biochars. Chemosphere, 92(8): 955-961.
[127]	Yamato M, Okimori Y, Wibowo I F, Anshori S, Ogawa M. 2006. Effects of the application of charred bark of acacia mangium on the yield of maize, cowpea and peanut, and soil chemical properties in South Sumatra, Indonesia. J Soil Sci Plant Nut, 52(4): 489-495.
[128]	Yang Y N, Sheng G Y. 2003. Enhanced pesticide sorption by soils containing particulate matter from crop residue burns. Environ Sci Technol, 37(6): 3635-3639.
[129]	Yao Y, Gao B, Zhang M, Inyang M, Zimmerman A R. 2012. Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. Chemosphere, 89(11): 1467-1471.
[130]	Yuan P, Wang J Q, Pan Y J, Shen B X, Wu C F. 2019. Review of biochar for the management of contaminated soil: Preparation, application and prospect. Sci Total Environ, 659: 473-490.
[131]	Zareabyaneh H, Bayatvarkeshi M. 2015. Effects of slow-release fertilizers on nitrate leaching, its distribution in soil profile, N-use efficiency, and yield in potato crop. Environ Earth Sci, 74(4): 3385-3393.
[132]	Zhang X K, Wang H L, He L Z, Lu K P, Sarmah A, Li J W, Bolan N S, Pei J C, Huang H G. 2013. Using biochar for remediation of soils contaminated with heavy metals and organic pollutants. Environ Sci Pollut Res Int, 20(12): 8472-8483.
[133]	Zhao B W, Xu R Z, Ma F F, Li Y W, Wang L. 2016. Effects of biochars derived from chicken manure and rape straw on speciation and phytoavailability of Cd to maize in artificially contaminated loess soil. J Environ Manage, 184: 569-574.
[134]	Zhao X, Wang J W, Wang S Q, Xing G X. 2014. Successive straw biochar application as a strategy to sequester carbon and improve fertility: A pot experiment with two rice/wheat rotations in paddy soil. Plant Soil, 378: 279-294.
[135]	Zhao X L, Yuan G Y, Wang H Y, Lu D J, Chen X Q, Zhou J M. 2019. Effects of full straw incorporation on soil fertility and crop yield in rice-wheat rotation for silty clay loamy cropland. Agronomy, 9(3): 133.
[136]	Zhelezova A, Cederlund H, Stenström J. 2017. Effect of biochar amendment and ageing on adsorption and degradation of two herbicides. Water Air Soil Pollut, 228(6): 216.
[137]	Zheng R L, Chen Z, Cai C, Wang X H, Huang Y Z, Xiao B, Sun G X. 2013. Effect of biochars from rice husk, bran, and straw on heavy metal uptake by pot-grown wheat seedling in a historically contaminated soil. Bioresources, 8(4): 5965-5982.
[138]	Zhong J K, Liu L, Zhong Z W, Yang Q Z, Zhang J Y, Wang L G. 2018. Advances on the research of the effect of biochar on the environmental behavior of antibiotics. J Saf Environ, 18: 657‒663. (in Chinese with English abstract)
[139]	Zou Y, Yang T. 2019. Rice husk, rice husk ash and their applications. Rice Bran Rice Bran Oil, 1: 207‒246.

Region	2014		2018
Region	Paddy rice	Rice husk	Paddy rice	Rice husk
Global	742.4	148.4	782.1	156.4
Africa	30.7	6.1	33.2	6.6
America	37.7	7.5	38.8	7.8
Asia	669.2	133.8	705.4	141.1
Europe	4.0	0.8	4.0	0.8
Oceania	0.8	0.2	0.7	0.1

Region	2014		2018
Region	Paddy rice	Rice husk	Paddy rice	Rice husk
Global	742.4	148.4	782.1	156.4
Africa	30.7	6.1	33.2	6.6
America	37.7	7.5	38.8	7.8
Asia	669.2	133.8	705.4	141.1
Europe	4.0	0.8	4.0	0.8
Oceania	0.8	0.2	0.7	0.1

Material	PT (ºC)	C (mg/kg)	H (mg/kg)	N (mg/kg)	P (mg/kg)	K (mg/kg)	H/C	O/C	Ash (%)	pH	EC (dS/m)	CEC (cmol_c/kg)	SSA (m²/g)	Reference
RH	-	362-445	43-63	3.2-10.0	0.04-1.40	1.2-24.0	-	-	18-21	6.5-6.8	-	11.2	-	Haefele et al, 2008; Masulili et al, 2010; Shackley et al, 2012
RHC ^a	-	350.0	1.7	7.0	-	-	0.06	-	63.0	9.6	-	45-110	-	Shackley et al, 2012
RHB	250-300	-	-	-	-	-	-	-	49.4	8.2	-	-	-	Singh et al, 2018
RHB	250-300	451.1	29.8	5.4	0.01	6.2	0.79	0.22	38.0	7.4	0.36	-	-	Abrishamkesh et al, 2015, 2017
RHB	300	415.8	-	17.7	1.19	0.2	-	-	-	7.1	-	49.4	-	Eduah et al, 2019
RHB	300	470.0	43.0	3.2	-	-	1.10	-	-	8.7	0.72	48.9	-	Munda et al, 2016
RHB	300	512.9	-	4.5	-	3.5	-	-	21.8	6.8	0.09	-	-	Nwajiaku et al, 2018
RHB	300	520.6	38.5	16.5	-	-	0.89	0.61	32.5	7.5	-	-	2.6	Wei et al, 2017
RHB	300	205.5	-	3.8	1.80	14.5	-	-	63.5	7.5	0.27	-	-	Manolikaki and Diamadopoulos, 2017
RHB	< 350	422.0	28.9	5.4	0.95	12.0	0.82	0.39	-	7.4	0.58	5.9	2.5	Tsai and Chang, 2020
RHB	< 350	404.0	32.9	6.3	1.51	13.2	0.98	0.45	-	7.2	0.67	4.4	2.5	Tsai and Chang, 2020
RHB	350	667.3	42.9	2.8	-	-	0.77	0.32	4.0	-	-	-	-	Huang et al, 2017
RHB	350-400	511.3	-	3.0	-	9.2	-	-	-	8.5	-	-	-	Oladele, 2019
RHB	350-400	427.0	-	4.0	-	8.7	-	-	-	8.4	0.35	-	-	Win et al, 2019 Koyama et al, 2016;
RHB	400	360.6	-	4.9	0.38	3.2	-	-	-	7.9	-	-	- -	Liu C Y et al, 2017
RHB	400	541.1	-	4.9	-	4.2	-	-	27.5	8.6	0.13	-	- -	Nwajiaku et al, 2018
RHB	450	419.8	-	13.3	1.32	1.1	-	-	-	7.4	-	42.7	- - - -	Eduah et al, 2019
RHB	450	454.0	24.0	5.0	-	-	0.63	0.19	-	-	-	40.1		Fazeli et al, 2020
RHB	450-500	442.4	19.0	5.6	0.03	7.4	0.52	0.11	47.0	8.4	0.48	-		Abrishamkesh et al, 2015
RHB	500	546.7	-	4.7	-	3.6	-	-	32.8	10.4	0.23	-		Nwajiaku et al, 2018
RHB	500	567.1	19.8	13.9	-	-	0.42	0.53	44.4	10.5	-	-	18.4	Wei et al, 2017
RHB	500	478.0	24.3	-	-	-	0.66	-	-	9.2	0.35	17.6	-	Ghorbani et al, 2019
RHB	> 500	492.0	22.9	7.1	1.71	19.6	0.56	0.21	-	8.4	0.40	3.1	2.7	Tsai and Chang, 2020
RHB	> 500	522.0	23.5	6.5	1.20	20.9	0.54	0.21	-	8.4	0.50	7.1	2.8	Tsai and Chang, 2020
RHB	550	780.8	33.6	1.0	-	-	0.52	0.18	21.5	-	-	-	-	Huang et al, 2017
RHB	600	-	-	-	-	-	-	-	-	10.3	0.53	19.5	-	Gamage et al, 2016
RHB	600	519.0	24.8	6.2	1.21	16.7	0.57	0.22	-	7.9	0.19	4.1	2.8	Tsai and Chang, 2020
RHB	600	560.6	-	4.3	-	3.1	-	-	33.9	10.6	0.31	-	-	Nwajiaku et al, 2018
RHB	600	512.0	-	7.8	5.14	3.4	-	-	-	10.4	-	-	-	Huang et al, 2018
RHB	> 600	409.7	17.2	4.7	-	-	0.11	0.15	48.2	9.7	-	-	179.0	Pratiwi et al, 2016
RHB	650	425.5	-	12.1	1.52	1.5	-	-	-	9.5	-	38.0	-	Eduah et al, 2019
RHB	700	545.0	-	3.6	-	3.1	-	-	35.6	10.7	0.40	-	-	Nwajiaku et al, 2018
RHB	700	511.0	25.5	6.2	0.95	15.4	0.60	0.22	-	8.1	0.17	4.3	2.8	Tsai and Chang, 2020
RHB	750	640.8	12.8	9.6	-	-	0.24	0.51	49.9	10.5	-	-	53.1	Wei et al, 2017
Mean	-	491.2	27.3	6.7	1.35	8.1	0.60	0.31	36.7	8.7	0.37	21.9	26.9
Max	-	780.8	43.0	17.7	5.14	20.9	1.10	0.61	63.5	10.7	0.72	49.4	179.0
Min	-	205.5	12.8	1.0	0.01	0.2	0.11	0.11	4.0	6.8	0.09	3.1	2.5

Material	PT (ºC)	C (mg/kg)	H (mg/kg)	N (mg/kg)	P (mg/kg)	K (mg/kg)	H/C	O/C	Ash (%)	pH	EC (dS/m)	CEC (cmol_c/kg)	SSA (m²/g)	Reference
RH	-	362-445	43-63	3.2-10.0	0.04-1.40	1.2-24.0	-	-	18-21	6.5-6.8	-	11.2	-	Haefele et al, 2008; Masulili et al, 2010; Shackley et al, 2012
RHC ^a	-	350.0	1.7	7.0	-	-	0.06	-	63.0	9.6	-	45-110	-	Shackley et al, 2012
RHB	250-300	-	-	-	-	-	-	-	49.4	8.2	-	-	-	Singh et al, 2018
RHB	250-300	451.1	29.8	5.4	0.01	6.2	0.79	0.22	38.0	7.4	0.36	-	-	Abrishamkesh et al, 2015, 2017
RHB	300	415.8	-	17.7	1.19	0.2	-	-	-	7.1	-	49.4	-	Eduah et al, 2019
RHB	300	470.0	43.0	3.2	-	-	1.10	-	-	8.7	0.72	48.9	-	Munda et al, 2016
RHB	300	512.9	-	4.5	-	3.5	-	-	21.8	6.8	0.09	-	-	Nwajiaku et al, 2018
RHB	300	520.6	38.5	16.5	-	-	0.89	0.61	32.5	7.5	-	-	2.6	Wei et al, 2017
RHB	300	205.5	-	3.8	1.80	14.5	-	-	63.5	7.5	0.27	-	-	Manolikaki and Diamadopoulos, 2017
RHB	< 350	422.0	28.9	5.4	0.95	12.0	0.82	0.39	-	7.4	0.58	5.9	2.5	Tsai and Chang, 2020
RHB	< 350	404.0	32.9	6.3	1.51	13.2	0.98	0.45	-	7.2	0.67	4.4	2.5	Tsai and Chang, 2020
RHB	350	667.3	42.9	2.8	-	-	0.77	0.32	4.0	-	-	-	-	Huang et al, 2017
RHB	350-400	511.3	-	3.0	-	9.2	-	-	-	8.5	-	-	-	Oladele, 2019
RHB	350-400	427.0	-	4.0	-	8.7	-	-	-	8.4	0.35	-	-	Win et al, 2019 Koyama et al, 2016;
RHB	400	360.6	-	4.9	0.38	3.2	-	-	-	7.9	-	-	- -	Liu C Y et al, 2017
RHB	400	541.1	-	4.9	-	4.2	-	-	27.5	8.6	0.13	-	- -	Nwajiaku et al, 2018
RHB	450	419.8	-	13.3	1.32	1.1	-	-	-	7.4	-	42.7	- - - -	Eduah et al, 2019
RHB	450	454.0	24.0	5.0	-	-	0.63	0.19	-	-	-	40.1		Fazeli et al, 2020
RHB	450-500	442.4	19.0	5.6	0.03	7.4	0.52	0.11	47.0	8.4	0.48	-		Abrishamkesh et al, 2015
RHB	500	546.7	-	4.7	-	3.6	-	-	32.8	10.4	0.23	-		Nwajiaku et al, 2018
RHB	500	567.1	19.8	13.9	-	-	0.42	0.53	44.4	10.5	-	-	18.4	Wei et al, 2017
RHB	500	478.0	24.3	-	-	-	0.66	-	-	9.2	0.35	17.6	-	Ghorbani et al, 2019
RHB	> 500	492.0	22.9	7.1	1.71	19.6	0.56	0.21	-	8.4	0.40	3.1	2.7	Tsai and Chang, 2020
RHB	> 500	522.0	23.5	6.5	1.20	20.9	0.54	0.21	-	8.4	0.50	7.1	2.8	Tsai and Chang, 2020
RHB	550	780.8	33.6	1.0	-	-	0.52	0.18	21.5	-	-	-	-	Huang et al, 2017
RHB	600	-	-	-	-	-	-	-	-	10.3	0.53	19.5	-	Gamage et al, 2016
RHB	600	519.0	24.8	6.2	1.21	16.7	0.57	0.22	-	7.9	0.19	4.1	2.8	Tsai and Chang, 2020
RHB	600	560.6	-	4.3	-	3.1	-	-	33.9	10.6	0.31	-	-	Nwajiaku et al, 2018
RHB	600	512.0	-	7.8	5.14	3.4	-	-	-	10.4	-	-	-	Huang et al, 2018
RHB	> 600	409.7	17.2	4.7	-	-	0.11	0.15	48.2	9.7	-	-	179.0	Pratiwi et al, 2016
RHB	650	425.5	-	12.1	1.52	1.5	-	-	-	9.5	-	38.0	-	Eduah et al, 2019
RHB	700	545.0	-	3.6	-	3.1	-	-	35.6	10.7	0.40	-	-	Nwajiaku et al, 2018
RHB	700	511.0	25.5	6.2	0.95	15.4	0.60	0.22	-	8.1	0.17	4.3	2.8	Tsai and Chang, 2020
RHB	750	640.8	12.8	9.6	-	-	0.24	0.51	49.9	10.5	-	-	53.1	Wei et al, 2017
Mean	-	491.2	27.3	6.7	1.35	8.1	0.60	0.31	36.7	8.7	0.37	21.9	26.9
Max	-	780.8	43.0	17.7	5.14	20.9	1.10	0.61	63.5	10.7	0.72	49.4	179.0
Min	-	205.5	12.8	1.0	0.01	0.2	0.11	0.11	4.0	6.8	0.09	3.1	2.5

Reference	H/C	Si	N	H	C	Ash	EC	pH	Feedstock	PT (ºC)
Reference	H/C	(g/kg)	(g/kg)	(g/kg)	(g/kg)	(%)	(dS/m)	pH	Feedstock	PT (ºC)
Phuong et al, 2015	0.69	-	3.0	28.0	478.0	35.3	-	9.9	Rice husk	350
	0.68	-	12.0	30.0	525.0	23.4	-	10.5	Rice straw	350
	0.05	-	3.0	22.0	487.0	39.4	-	9.9	Rice husk	450
	0.04	-	10.0	23.0	521.0	30.8	-	10.4	Rice straw	450
	0.03	-	3.0	16.0	512.0	40.5	-	10.4	Rice husk	550
	0.03	-	7.0	18.0	580.0	33.5	-	11.7	Rice straw	550
Eduah et al, 2019	-	138.5	7.1	-	415.8	-	-	7.1	Rice husk	300
	-	13.9	8.9	-	729.8	-	-	8.9	Corn cob	300
	-	169.2	7.4	-	419.8	-	-	7.4	Rice husk	450
	-	14.0	9.2	-	743.1	-	-	9.2	Corn cob	450
	-	194.5	9.5	-	425.5	-	-	9.5	Rice husk	650
	-	14.4	10.3	-	780.7	-	-	10.3	Corn cob	650
Nwajiaku et al, 2018	-	-	4.9	-	541.1	27.5	0.13	8.6	Rice husk	400
	-	-	5.7	-	707.3	11.0	0.12	8.3	Sugarcane bagasse	400
	-	-	4.7	-	546.7	32.8	0.23	10.4	Rice husk	500
	-	-	5.3	-	729.5	11.5	0.16	9.2	Sugarcane bagasse	500
	-	-	4.3	-	560.6	33.9	0.31	10.6	Rice husk	600
	-	-	4.7	-	702.2	12.4	0.17	9.6	Sugarcane bagasse	600
	-	-	3.6	-	545.0	33.6	0.40	10.7	Rice husk	700
	-	-	3.8	-	696.3	12.8	0.21	9.7	Sugarcane bagasse	700
Fazeli et al, 2020	0.63	-	5.0	24.0	454.0	-	-	-	Rice husk	450
	0.43	-	9.0	27.0	752.0	-	-	-	Wood
	0.76	-	39.0	37.0	582.0	-	-	-	Tea waste
Kizito et al, 2015	-	-	8.9	20.6	379.1	42.0	0.29	7.8	Rice husk	600
Kizito et al, 2015	-	-	7.3	7.9	863.0	5.9	0.41	9.8	Wood	600
Manolikaki and Diamadopoulos, 2017	-	-	0.8	-	205.5	63.5	0.27	7.5	Rice husk	300
Manolikaki and Diamadopoulos, 2017	-	-	16.0	-	466.0	25.7	1.06	10.8	Grape pomace	300