TY - JOUR
T1 - Risks and benefits of marginal biomass-derived biochars for plant growth
AU - Buss, Wolfram
AU - Graham, Margaret C.
AU - Shepherd, Jessica G.
AU - Mašek, Ondřej
N1 - Publisher Copyright:
© 2016 Elsevier B.V.
PY - 2016/11/1
Y1 - 2016/11/1
N2 - In this study, 19 biochars from marginal biomass, representing all major biomass groups (woody materials, grass, an aquatic plant, anthropogenic wastes) were investigated regarding their content of available potentially toxic elements (PTEs) and nutrients (determined by NH4NO3-extractions) and their effects on cress (Lepidium sativum) seedling growth. The objective was to assess the potential and actual effects of biochar with increased PTE content on plant growth in the context of use in soil amendments and growing media. It showed that the percentage of available PTEs was highest for biochars produced at the highest treatment temperature (HTT) of 750 °C. On average, however, for all 19 biochars, the percentage availability of Cu, Cr, Ni and Zn (< 1.5% for all) was similar to the percentage availability reported in the literature for the same elements in soils at similar pH values which is a highly important finding. Most biochars exceeded German soil threshold values for NH4NO3-extractable PTEs, such as Zn (by up to 25-fold), As and Cd. Despite this, cress seedling growth tests with 5% biochar in sand did not show any correlations between inhibitory effects (observed in 5 of the 19 biochars) and the available PTE concentrations. Instead, the available K concentration and biochar pH were highly significantly, negatively correlated with seedling growth (K: p < 0.001, pH: p = 0.004). K had the highest available concentration of all elements and the highest percentage availability (47.7 ± 19.7% of the total K was available). Consequently, available K contributed most to the osmotic pressure and high pH which negatively affected the seedlings. Although a potential risk if some of these marginal biomass-derived biochar were applied at high concentrations, e.g. 5% (> 100 t ha− 1), when applied at agriculturally realistic application rates (1–10 t ha− 1), the resulting smaller increases in pH and available K concentration may actually be beneficial for plant growth.
AB - In this study, 19 biochars from marginal biomass, representing all major biomass groups (woody materials, grass, an aquatic plant, anthropogenic wastes) were investigated regarding their content of available potentially toxic elements (PTEs) and nutrients (determined by NH4NO3-extractions) and their effects on cress (Lepidium sativum) seedling growth. The objective was to assess the potential and actual effects of biochar with increased PTE content on plant growth in the context of use in soil amendments and growing media. It showed that the percentage of available PTEs was highest for biochars produced at the highest treatment temperature (HTT) of 750 °C. On average, however, for all 19 biochars, the percentage availability of Cu, Cr, Ni and Zn (< 1.5% for all) was similar to the percentage availability reported in the literature for the same elements in soils at similar pH values which is a highly important finding. Most biochars exceeded German soil threshold values for NH4NO3-extractable PTEs, such as Zn (by up to 25-fold), As and Cd. Despite this, cress seedling growth tests with 5% biochar in sand did not show any correlations between inhibitory effects (observed in 5 of the 19 biochars) and the available PTE concentrations. Instead, the available K concentration and biochar pH were highly significantly, negatively correlated with seedling growth (K: p < 0.001, pH: p = 0.004). K had the highest available concentration of all elements and the highest percentage availability (47.7 ± 19.7% of the total K was available). Consequently, available K contributed most to the osmotic pressure and high pH which negatively affected the seedlings. Although a potential risk if some of these marginal biomass-derived biochar were applied at high concentrations, e.g. 5% (> 100 t ha− 1), when applied at agriculturally realistic application rates (1–10 t ha− 1), the resulting smaller increases in pH and available K concentration may actually be beneficial for plant growth.
KW - Availability
KW - Biochar
KW - Contaminants
KW - Heavy metals
KW - Phytotoxicity
KW - Potentially toxic elements
UR - http://www.scopus.com/inward/record.url?scp=84976384240&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2016.06.129
DO - 10.1016/j.scitotenv.2016.06.129
M3 - Article
SN - 0048-9697
VL - 569-570
SP - 496
EP - 506
JO - Science of the Total Environment
JF - Science of the Total Environment
ER -