4. Discussion
Both char materials had an overall positive effect on the aboveground growth of wheat plants in our pot experiment when
compared with the influence of uncharred corn silage. This is in agreement with the results from a meta-analysis who found an average increase in crop yield of 10% when soils were amended with biochar produced via pyrolysis.
found no toxic effects of freshly produced pyrochar (from pine wood chips) on the growth of Lolium perenne. In contrast, a reduction in shoot biomass of Medicago sativa and the occurrence of leaf tip necroses in the presence of biochar produced via hydrothermal carbonization from spent brewer's grains . Likewise,noticed growth reductions in Taraxacum and Trifolium plants if hydrochar was applied at rates above 10 vol%. In our study, the shoot dry weight of plants grown with either type of char was higher than that of plants grown with corn silage and the results of the chlorophyll fluorescence measurements point to an active photosystem II, especially in the presence of hydrochar. Toxic
effects could thus be limited to the process of germination, which was reduced in the presence of hydrochar.