Using biochar for environmental recovery and boosting the yield of valuable non-food crops: The case of hemp in a soil contaminated by potentially toxic elements (PTEs)
Matteo Garau,
Mauro Lo Cascio,
Sotirios Vasileiadis,
Tom Sizmur,
Maria Nieddu,
Maria Vittoria Pinna,
Costantino Sirca,
Donatella Spano,
Pier Paolo Roggero,
Giovanni Garau,
Paola Castaldi
Affiliations
Matteo Garau
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy
Mauro Lo Cascio
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; CMCC – Euro-Mediterranean Center on Climate Change Foundation, IAFES Division, Via de Nicola 9, 07100, Sassari, Italy
Sotirios Vasileiadis
Department of Biochemistry and Biotechnology, University of Thessaly, Greece
Tom Sizmur
Department of Geography and Environmental Science, University of Reading, Reading, RG6 6DW, UK
Maria Nieddu
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy
Maria Vittoria Pinna
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy
Costantino Sirca
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; CMCC – Euro-Mediterranean Center on Climate Change Foundation, IAFES Division, Via de Nicola 9, 07100, Sassari, Italy
Donatella Spano
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; CMCC – Euro-Mediterranean Center on Climate Change Foundation, IAFES Division, Via de Nicola 9, 07100, Sassari, Italy
Pier Paolo Roggero
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; Nucleo Ricerca Desertificazione, University of Sassari, Sassari, Italy
Giovanni Garau
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; Corresponding author. Viale Italia 39, 07100, Sassari, Italy.
Paola Castaldi
Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100, Sassari, Italy; Nucleo Ricerca Desertificazione, University of Sassari, Sassari, Italy
Hemp (Cannabis sativa L.) is known to tolerate high concentrations of soil contaminants which however can limit its biomass yield. On the other hand, organic-based amendments such as biochar can immobilize soil contaminants and assist hemp growth in soils contaminated by potentially toxic elements (PTEs), allowing for environmental recovery and income generation, e.g. due to green energy production from plant biomass. The aim of this study was therefore to evaluate the suitability of a softwood-derived biochar to enhance hemp growth and promote the assisted phytoremediation of a PTE-contaminated soil (i.e., Sb 2175 mg kg−1; Zn 3149 mg kg−1; Pb 403 mg kg−1; and Cd 12 mg kg−1). Adding 3% (w/w) biochar to soil favoured the reduction of soluble and exchangeable PTEs, decreased soil dehydrogenase activity (by ∼2.08-fold), and increased alkaline phosphomonoesterase and urease activities, basal respiration and soil microbial carbon (by ∼1.18-, 1.22-, 1.22-, and 1.66-fold, respectively). Biochar increased the abundance of selected soil culturable microorganisms, while amplicon sequencing analysis showed a positive biochar impact on α-diversity and the induction of structural changes on soil bacterial community structure. Biochar did not affect root growth of hemp but significantly increased its aboveground biomass by ∼1.67-fold for shoots, and by ∼2-fold for both seed number and weight. Biochar increased the PTEs phytostabilisation potential of hemp with respect to Cd, Pb and Zn, and also stimulated hemp phytoextracting capacity with respect to Sb. Overall, the results showed that biochar can boost hemp yield and its phytoremediation effectiveness in soils contaminated by PTEs providing valuable biomass that can generate profit in economic, environmental and sustainability terms.
