Criterious preparation and characterization of earthworm-composts in view of animal waste recycling. Part II. A synergistic utilization of EPR and H-1 NMR spectroscopies on the characterization of humic acids from vermicomposts

Humic acids (HA) extracted from sheep (SHHA), cow (COHA), goat (GOHA) and r abbit (RAHA) vermicomposted manure were analyzed by electron paramagnetic r esonance and hydrogen nuclear magnetic resonance spectroscopies. Carboxylic acids, amine, amide, ester, ether and phenol functions bonded to saturated aliphatic, unsaturated aliphatic conjugated double and single bonds, and a romatic chains constitute the backbone structure of these fresh humic subst ances (HS). Mn2+ outer sphere complexes (SHHA, COHA), Fe3+ axial (COHA, RAH A) or rhombic (SHAHA, COHA, GOHA, RAHA) complexes and Cu2+ as weak field (C OHA, GOHA, RAHA) and strong field (SHAHA, COHA, GOHA, RAHA) complexes were characterized.