1. New Zealand Biochar Research Centre; Soil and Earth Sciences Group; Institute of Natural Resources; Massey University; Private Bag 11222 Palmerston North 4442 New Zealand
2. Department of Export Agriculture; Faculty of Animal Science and Export Agriculture; Uva Wellassa University; Badulla 90000 Sri Lanka
3. Landcare Research; Private Bag 11052 Palmerston North 4442 New Zealand
4. Department of Chemistry; Iso-trace Research; University of Otago; Union Street West PO Box 56 Dunedin 9054 New Zealand