Relation between biochar properties and effects on seed germination and plant development

Biochar can provide multiple benefits in the ecosystem. However, an important concern, which needs to be addressed, is the presence of phytotoxic compounds in some biochars. In this work seed germination and plant development are reported for three biochars prepared from wood, paper sludge plus wheat husks and sewage sludge on five higher plant species (cress, lentil, cucumber, tomato and lettuce). In general, seed germination was not affected except for the inhibition caused by wood biochar in several species and the inhibition induced by paper sludge biochar on lettuce. No inhibition of root growth was detected, but in some cases leaf and stem growth were inhibited. The results are significant in terms of advancing current understanding on the impacts of biochar on vegetative growth and linking those effects to biochar inherent properties.