Biochar application has significant potential effects on soil fertility, but these are highly dependent on the interactions between a specific biochar material and the soil type in which it is applied. In general, overall increases of crop yields have been observed mainly in weathered tropical soils, but by exploiting specific interactions between biochar, soil and crop, positive effects on soil fertility and crop growth can also be expected in temperate regions. Examples of these effects as well as current knowledge gaps and research needs are presented.