Contact the American Geographical Society. The AGS offers a number of fellowships and scholarships for advanced degree students in land sciences.
Apply for a fellowship through Lambda Alpha International. Lambda Alpha administers research grants for geography through the Land Economics Foundation, a nonprofit organization which promotes the study of land economics and geography.
Contact the U.S. Geospatial Intelligence Foundation, which provides fellowship support to students entering the field of geospatial intelligence. Deadlines for the scholarship are typically in early May.
Apply for a geography fellowship through the institution you attend. Most large geography programs offer fellowships for talented students. These fellowships typically include a teaching assistantship as well as field research.