The Fourth International Conference on Agro-Geoinformatics (Agro-Geoinformatics 2015) will be held in Istanbul, Turkey, on July 20-24, 2015. This conference is organized and hosted by TARBIL Agricultural Informatics Applied Research Center and Istanbul Technical University (ITU), with technical and financial sponsorships from Republic of Turkey Ministry of Food, Agriculture and Live stock, Institute of Agricultural Resources and Regional Planning of CAAS, USDS NASS, OGC, IEEE GRSS and many other organizations. The Center for Spatial Information Science and Systems (CSISS) of George Mason University is the co-organizer. Agro-geoinformation is critical for the agricultural sustainability, food security, environmental research, bioenergy, natural resource conservation, land use management, carbon accounting, global climate change, health research, agricultural industry, commodity trading, economy research, education, agricultural decision making and policy formulation, etc. The Agro-Geoinformaticsconferences were successfully held in Shanghai, China (Agro-Geoinformatics 2012), Washington DC, USA(Agro-Geoinformatics 2013), and Beijing, China (Agro-Geoinformatics 2014). The Agro-Geoinformatics conferences have provided and will continue to provide an ideal venue for professionals and students to exchange their ideas, research results, professional experiences, the latest developments and future vision of agro-geoinformatics. The Agro-Geoinformatics 2015 conference will continue covering the recent advances in the life cycle of Agro-geoinformatics, from data collection (including field surveys and remote sensing), processing, storing, archiving, preservation, retrieving, transmitting, accessing, visualization, analyzing, synthesizing, presenting, disseminating to decision making.