Sulawesi plots soil metals

Soil samples were collected from each of the 10 x 10 m subplots within each plot and pooled to form a single sample per plot. Total C measurement used the Walkley and Black method, total N the Kjeldahl method and total soil Al, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P and Zn was quantified via digestion of 0.5 g soil in 5 ml HNO3 and 1 ml HClO4 at 100 to 200 ° C by ramping over a 7 hour period then diluted to 25 ml with deionised water and analysis on an Agilent Technologies 4100 microwave plasma atomic emission spectrometer (Co, Cr and Ni) or an Agilent Technologies 200 Series atomic absorption spectrometer (all other elements).