Acid soils comprise up to 50% of the world’s potentially arable land and thus are a significant limitation to crop production worldwide. To address the many problems associated with acid soils, the First International Symposium on Plant-Soil Interactions at Low pH (PSILPH) was successfully held in Canada in 1987, followed by subsequent symposiums in USA (1990), Australia (1993), Brazil (1996), South Africa (2001) and Japan (2004). Since its opening, this symposium has provided great opportunities for scientists around the globe to exchange information and ideas on all aspects of plant-soil interactions at low pH.