←Dr. Johan Perret is professor of Soil Management and Precision Agriculture at EARTH University, Costa Rica. His main focus has been on sustainable soil management and efficient use of fertilizers and water in agriculture. Prof. Perret uses innovative technologies like global positioning systems (GPS) combined with real-time field diagnosis sensors (pH, soil moisture, compaction, salinity, chlorophyll sensors, etc..) for soil mapping. This creates the scientific and quantitative basis allowing "site-specific" optimized decision making which in turns lead to a cheaper and more environmental friendly agriculture. Dr. Perret has developed new techniques of aerial photography and photogrammetry to determine and identify "hot spots" in production systems, such as areas with nutritional deficiencies, problems of water deficit, low plant density, problems waterlogging, and critical areas of erosion. Dr. Perret gives several talks and consultations each year on topics of precision agriculture, plant nutrition and fertilization, and sustainable soil management and conservation. He has over 15 years of experience in training and has conducted workshops internationally. He has advised over 30 theses in the area of soil best management practices and fertility, soil mapping and precision agriculture, plant nutrition & environmental quality. Dr. Perret has authored or coauthored over 65 publications (scientific papers, extension bulletins, reports, popular articles and other media). Professor Perret earned his Ph.D. at McGill University in Canada in 1998 (Honors / CSAE Thesis Award in 1999).