HUMIC SUBSTANCES FORMED DURING THE COMPOSTING OF ORGANIC-MATTER

Humic substances (HS) were extracted from separated cattle-manure compost (CSM) at various stages of decomposition. Carbon-13 nuclear magnetic resonance (13C-NMR) and Fourier-transform infrared (FTIR) spectroscopy measurements were performed on the purified humic acids (HA), as well as crude fiber and chemical analyses. Levels of HS extracted from the CSM samples doubled during the composting (from 377 to 710 g kg-1 organic matter). The NMR data correlated well with results obtained by FTIR spectroscopy, both indicating that the CSM HA are composed of partially degraded constituents of plant tissue, which still retain to some extent their chemical structures. The major plant components identified in the HA were lignin, carbohydrates, and long-chain aliphatic structural groups. -from Authors