Detailed carbon chemistry in charcoals from pre-European Maori gardens of New Zealand as a tool for understanding biochar stability in soils

R. Calvelo has been partially funded by the New Zealand Agricultural Greenhouse Gas Research Centre. The authors would like to thank Dr W. Gumbley for kindly providing the archaeological M aori charcoal samples and the radiocarbon ages used here. They would like to thank the staff of the Departamento de Edafologia y Quimica Agricola, Universidad de Santiago de Compostela (Spain), for their collaboration in the elemental analysis. R. Calvelo would like to thank R. Higgins (Pomona College, USA) for laboratory assistance and Dr T. Wang (Massey University) for useful discussion of mineralization modelling.