Changing Phosphorus Availability with Ammonium Sulphate and Carbon Dioxide Enrichments in a Calcareous Soil

Abstract

LARGE amounts of ammonium sulphate and carbon dioxide have been released into the atmospheric environment due to intensive industrial and agricultural activities, such as an increased use of fossil fuels and disturbance of forests and soils. These inputs have led researchers to wonder what effects the changing atmospheric environment would have on global ecosystems. In a calcareous soil, addition of ammonium sulphate enhanced the fraction of anion resin exchangeable phosphorus, which represents the most bioavailable phosphorus forms. This finding suggests that deposition of ammonium sulphate may cause transport of phosphate anions, as well as some essential cations, from terrestrial to aquatic systems, accelerating potential eutrophication of water resources. Under high levels of CO₂, phosphorus availability was decreased probably due to abiotic adsorption of phosphorus onto complexes of soil minerals and CO₂ or microbial products induced by CO₂, reduced phosphorus availability may limit plant productivity in calcareous soils, and hence CO₂-stimulating photosynthesis would not continue to remove the greenhouse gas.