biogeochemistry of phosphorus after the first century of soil development on Rakata Island, Krakatau, Indonesia

This study examined the accumulation of organic carbon (C) and fractions of soil phosphorus (P) in soils developing in volcanic ash deposited in the 1883 eruption of Krakatau. Organic C has accumulated at rates of 45 to 127 g/m2/yr during 110 years of soil development, resulting in profiles with as much as 14 kgC/m2. Most soil P is found in the HCl-extractable forms, representing apatite. A loss of HCl-extractable P from the surface horizons is associated with a marked accumulation of NaOH-extractable organic P bound to Al. A bioassay with hill rice suggests that P is limiting to plant growth in these soils, perhaps as a result of the rapid accumulation of P in organic forms.