Table 7.

Effects of biochar application on crops growth and Cr uptake, grown on Cr-contaminated soils.

Plant specie	Feedstock	Applied rate	Soil type	Exp. type	Cr	Effect of Cr	References
Lettuce	Maize stalk (500°C)	0, 5 and 10 t/ha	Clay	Pot	Cr	The biochar amendment resulted in a drop in Cr concentration or even an improvement in soil fertility and nutrient uptake.	Nigussie et al. (2012)
Maize	Sugarcane bagasse (350°C)	0%, 3%	Silty clay loam	Pot	Cr	Biochar application significantly improved the growth and antioxidant activity of maize with reduction in Cr accumulation	Bashir et al. (2021)
Maize	Sugarcane bagasse (500°C) and acidified manure	3% and 5%	Silty loam	Pot	Cr	The inclusion of sugarcane bagasse biochar has the power to mitigate Cr activity in polluted soil and accretion in maize plant roots and shoots.	Abbas et al. (2020)
Maize	Cow manure (420°C)	5 g kg-1		Pot	Cr	Biochar application caused greater liming effect, improved the plant growth and shoot/root ratio and enzymatic activities	Liu et al. (2020)
Mustard green	Rice husk and maple leaves (550°C)	0.5, 1 and 2% w/w	Loamy sand	Pot	Cu, Pb, Cr	Rice husk and maple leaves reduced both leaching and phytoavailability of metals	Nejad and Jung (2017)
Maize	Biochar (agriculture residues) (500°C)	0, 1, 2.5, 5 and 10% w/w	Loamy sand	Pot	Pb, Cr	Biochar helps in reduction of metals	Alaboudi et al. (2019)
	Solid waste compost, coal fly ash, and rice husk (300°C and 600°C)	2 and 5% w/w	Clay loam	Laboratory incubation study	Cr	Chromium toxicity reduced with the addition of biochar and soil amendment	Saffari et al. (2014)
Spring barley	Industrially obtained wood	2.5%	Metal polluted soil	Pot	Zn, Mn, Cr, Cd, Pb, Cu	The use of biochar combined with metal-tolerant bacteria efficiently remediate the soil contaminated with heavy metals	Rajput et al. (2021)
Rice	Sewage sludge (550°C)	5 and 10% w/w	loamy sand	Pot	Cr, Cu, Co	The incorporation of biochar to the soil boosted soil fertility while lowering hazardous metal bioaccumulation.	Khan S. et al. (2013)
Mustard	Chicken manure	0,50 g kg-1	Calcic red clay		Cr	In soil Cr(VI) transformed into Cr(III), decreased Cr in plants and boosted dry matter	Choppala et al. (2015)
Rice	Rice residues (straw, husk, bran) 500°C	5% w/w		Pot	Multi-metal contaminated soil	Metal uptake was slowed in rice seedlings, plant growth and biomass enhanced, and mineral content in iron plaque began to rise.	Zheng et al. (2012)
	Orchard prune residue (500°C)	0, 1, 5 and 10% w/w	clay		Mine tailings with Cr, Cu, Pb and Zn	Maximum utilization of biochar minimized leachable Cd, Pb, and Cr.	Fellet et al. (2011)
	Chitosan and Hematite (600°C)	1% w/w	Cr polluted calcareous soil	Plastic bag	Cr	Application of chitosan boosted Cr(VI) reduction from 28.53% (biochar) to 46.23% and inclusion of hematite from 28.55% (biochar) to 38.95%.	Zibaei et al. (2020)
	Poultry manure, cow manure, sheep manure biochar (450°C)	5% w/w		Incubation experiment	Cr	Biochar application helps in the reduction of Cr(VI) in contaminated soil	Mandal et al. (2017)
Maize and cowpea	Composted tannery sludge (CTS)	O, 2.5, 5,10, 20 Mg ha-1	Sandy loam	Field experiment	Cr	Due to the application of CTS and similar addition of Cr in roots and shoots leads to the higher growth of maize and cowpea plants	Sousa et al. (2018)
Cherry tomato (Lycopersicon esculentum)	Waste-water sludge (550°C)	10 t ha-1	Chromosol (Australian system)	Greenhouse pot trial	As, Cd, Cr, Cu, Pb, Zn	The application of biochar increased cherry tomato production by 64% and increased the availability of nutrients	Hossain et al. (2010)
Kidney vetch (Anthyllis vulneraria), Round-leaved Hellerkraut (Noccaea rotundifolnum L.), and alpine bluegrass (Poa alpine L.) alpine	Pruning residues from orchard (550°C), fir tree pellets and manure pellets mixed with fir tree pellets (350-400°C)	0, 1.5, and 3%	Technosol	Pot	Cd, cr	Different type of biochar promote plant growth for phytostabilization of mine tailing	Fellet et al. (2014)
Paddy rice	Whine lees (600°C)	0.5 and 1%		Pot	Cr, ni, cu, zn, cd, pb	Exchangeable Cr, Ni, Cu, Pb, Zn, and Cd decreased in soil due to increased soil pH and were also reduced in plant roots, stems, leaves, and rice husk with wine lees-derived BC.	Zhu et al. (2015)
Tomato (Lycopersicon esculentum L.)	Woody biomass (Gliricidia sepium) 900°C	1, 2.5 and 5% w/w	Serpentine soil	Pot	Ni, cr, mn	BC derived from woody biomass maximized the immobilization of Cr, Ni, and Mn in serpentine soil and minimized metal-induced toxicities in tomato plants.	Herath et al. (2015)