EFFECTS ON SEED GERMINATION OF DIFFERENT BIOCHARS FROM INDUSTRIAL THERMOCHEMICAL PROCESSES

Char or biochar is a type of charcoal obtained from gasification/pyrolysis of biomasses. Instead of burning standing biomass from cleared forest, the resource is charred. The result is a highly porous, carbon-rich solid residue, really similar in appearance to the coal produced by natural burning. First considered an industrial waste, in recent years, the interest in this material has grown enormously given its ability to improve physical, chemical, biological and mechanical properties of soils, when used as amendment. However, its effects are highly variable depending onits chemical-physical properties which in turn depend greatly on the starting feedstock. The present study reports about the effects of different chars obtained from industrial thermo-chemical processes (gasification for energy production) on soil quality. In particular, radish germination was monitored using conifer, poplar and marc biochar as amendment. Results revealed that radish roots had different lengths depending on the nature of biomassesused to produce the different chars. Actually, the char produced from marc completely inhibited seeds germination. Moreover, to investigate the effect of the genotype, a study is going on regarding the influence of different biochars on seed germination of Troyer citrange [Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.].High resolution solid state NMR spectroscopy revealed no differences among the chemical nature of the different chars. Conversely, low resolution 1H fast field cycling NMR relaxometry showed that porosity of chars was directly related to the nature of the biomassesused for the thermo-chemical transformations. We can conclude that not all the chars can be applied to soil to improve its quality, thus a careful characterization must be carried out prior to field application in order to avoid counter-effects which can damage soil productivity.