This paper outlines experiences with a recent campaign to collect volunteered geographic information VGI) on land cover and human impact using the Geo-Wiki crowdsourcing tool (humanimpact.geo-wiki.org) A targeted campaign approach was adopted with the aim of gathering data for the validation of a map of land availability for biofuels. At the same time, experimentation was undertaken to assess the quaity of information from the crowd. Some initial results of the campaign are presented along with lessons learned and future developments.