Sorghum bicolor · Atlas of Contaminated Sites

How it works

Mechanisms: phytoextraction

Contaminants

Contaminant	Evidence	What was shown
Zinc	field	At Torviscosa (Udine), on soil polluted by pyrite cinders with 980 mg/kg Zn, removal of about 2,000 g Zn/ha, twice that of sunflower in the same trial (Marchiol et al. 2007). Marchiol et al., Removal of trace metals by Sorghum bicolor and Helianthus annuus in a site polluted by industrial wastes: a field experience, Plant Physiol. Biochem. 45:379, 2007
Cadmium	field	In a three-year unfertilised trial on smelter-polluted alluvium (Příbram, Czechia), it is among the herbaceous crops the authors recommend for Cd, Zn and Pb phytoextraction; woody species, willows in particular, extracted more (Mayerová et al. 2017). Mayerová et al., Non-enhanced phytoextraction of cadmium, zinc, and lead by high-yielding crops, Environ. Sci. Pollut. Res. 24:14706, 2017

Contaminant

Evidence

What was shown

field

At Torviscosa (Udine), on soil polluted by pyrite cinders with 980 mg/kg Zn, removal of about 2,000 g Zn/ha, twice that of sunflower in the same trial (Marchiol et al. 2007).

Marchiol et al., Removal of trace metals by Sorghum bicolor and Helianthus annuus in a site polluted by industrial wastes: a field experience, Plant Physiol. Biochem. 45:379, 2007

Cadmium

field

In a three-year unfertilised trial on smelter-polluted alluvium (Příbram, Czechia), it is among the herbaceous crops the authors recommend for Cd, Zn and Pb phytoextraction; woody species, willows in particular, extracted more (Mayerová et al. 2017).

Mayerová et al., Non-enhanced phytoextraction of cadmium, zinc, and lead by high-yielding crops, Environ. Sci. Pollut. Res. 24:14706, 2017

Limits

Removal on the order of 2 kg of zinc per hectare: not enough to clean a soil in a useful time. Organic amendment can bind metals and lower uptake (Marchiol et al. 2007). It makes sense as a non-food crop giving income while the site stays under control; the end use of the biomass must be checked.

Where it has been tried

Caffaro di Torviscosa (formerly Grado and Marano Lagoon)

PhytoremediationField scale, 2005

Sorghum bicolor, Helianthus annuus

The University of Udine (Marchiol, Fellet, Perosa, Zerbi) grew sorghum and sunflower in randomised blocks on soil with As 309, Cd 4.29, Co 50.9, Cu 1,527 and Zn 980 mg/kg, comparing mineral fertiliser, organic amendment and a control, with relief irrigation.

Outcome Fertiliser and amendment raised biomass a great deal but not the metal concentration in the harvested tissue; in some cases organic matter made the elements less available. Zinc removal was about 2,000 g/ha with sorghum and 1,000 g/ha with sunflower: small amounts against what the soil holds.