Foreword: Understanding how plants cope with acid soils

Supplying food and fuel to meet the demands of a growing population is a challenge facing every society. Crop yields will need to increase significantly over the next 40 years to support an extra two billion people by 2050. Acid soils limit plant production around the world but especially in the tropical and sub-tropical latitudes where a large proportion of the population increases are expected to occur. Aluminium toxicity and phosphorus deficiency are two of the major stresses affecting plant growth on acid soils. How plants combat these stresses was a theme at the '7th International Symposium on Plant-Soil Interactions atLowpH', held in Guangzhou in 2009, and the focus of this issue ofFPB.We provide an overview of recent progress in the area and introduce a selection of invited papers for this research front on acid soils.