8 9 A comparison was made between the composition of the recalcitrant organic matter (ROM) 10 isolated from a sandy forest soil as revealed by microwave assisted extractions and/or 11 hydrolyses and by usual pyrolysis techniques. Successive microwave irradiation treatments 12 were performed in H2O, 0.1 and 1 M HCl and 0.1 and 1 M KOH. At each step of the 13 treatment the insoluble residue was e...