Biochar characterization and impacts on temperate agricultural soils-effects on soil fertility, crop yield and trace element behavior : Vortrag der Kubiena-Preisträgerin

Wien

2014

S. 15

Artikel aus einer ZeitschriftUnselbständiges Werk

200190095

Pyrolysis is the thermal decomposition of biomass under low-oxic conditions, which results in the formation of a solid, carbonaceous residue called biochar. The application of biochar to soils has been increasingly investigated in terms of soil amendment and long-term carbon sequestration. This dissertation studied the characteristics of various biochar types and investigated the effects of biochar on soil fertility, plant yield and trace element behavior in a greenhouse pot experiment. For the biochar characterization, various plant residues (wheat straw, poplar wood, spruce wood) were pyrolyzed at three different temperatures (400°C, 460°, 525°C) and analyzed for physico-chemical and molecular characteristics as well as polycyclic aromatic hydrocarbons and trace elements. The pot experiment included three agricultural soils and biochars produced from wheat straw, woodchips and vineyard pruning. All pots were equipped with an outlet to collect leachate water and planted with mustard (Sinapis alba L.), barley (Hordeum vulgare L.) and clover (Trifolium pratense L.). Results of the biochar characterization revealed that biochar properties were dependent on both feedstock and pyrolysis temperature. Increasing biochar aromaticity and thermal stability with increasing pyrolysis temperature demonstrate their potential for long-term C sequestration in the soil, but the accumulation of trace elements and the formation of polycyclic aromatic hydrocarbons have to be considered. Results of the pot experiment showed that biochar initially had detrimental effects on plant yield; only wheat straw biochar did not impair yields and even significantly increased barley yield. Generally, biochar application was most beneficial on a sandy, acidic soil. Effects of biochar on trace elements were dependent on soil and biochar type as well as trace element contents of the biochars. Biochar application increased the solubility and leaching of anionic trace elements and caused elevated anionic trace element concentrations in plants, but decreased cationic trace element concentrations. The dissertation highlights that the application of biochar to temperate soils can have beneficial effects but may also depress plant yield and entail environmentally and ecotoxicologically relevant consequences that affect soil, leachates and plants to different extents.