| Abstract: | The C-13 spectra at 75.4 MHz of various leaf and needle composts are studied as a function of the composting time, and the chemical changes observed are discussed. In addition, the C-13 spectra of humic acids produced from typical composted Mediterranean horticultural and agricultural waste like grapevine prunings, grape husks and wheat straw are examined. The spectra from all materials show increasingly poorer resolution with increasing composting time. No new C-13 signals to indicate the formation of new chemical entities are seen to occur during the process of composting. It is shown by quantitative ESR that the deterioration of the quality of the NMR spectra is not due to formation of additional free radicals during the composting process. |
