Large Changes in Soil Carbon and Nitrogen After Phosphorus Addition in Radiata Pine Plantations.

Many stands of Pinus radiata in south-eastern are growing on infertile sandy soils and respond greatly to phosphorus fertilization.   This causes large changes in the turnover of carbon and nitrogen and which are reflected in soil properties.  Research organizations in Australia have undertaken long-term studies of these stands and, in some cases, have archived soil samples dating back to the 1960s.  The large growth responses combined with archived soils has represented a unique opportunity to resample these stands and study the way in which addition of phosphorus has affected soil C:N ratios.  This talk will discuss the implications of these results for sustainability and also the widely held view, among some, that nitrogen must be added to soil to store additional carbon, especially in agriculture.