Spectral characteristics of soil dissolved organic matter: Long-term effects of exogenous organic matter on soil organic matter and spatial-temporal changes.

The aim of this study was to evaluate the long-term effect of urban and green waste compost exogenous organic matter (EOM) on soil dissolved organic matter (DOM). A luvic cambisol was amended 7 years before the study. DOM was investigated along a soil profile down to 1 m depth regarding seasonal variations (autumn and spring). DOM sampled by suction cups was characterized using dissolved organic carbon (DOC) content and excitation emission matrix (EEM) fluorescence. The variability of DOM concentrations was pronounced but no major change in composition was determined. The results obtained, reinforced by statistical analysis, showed that the DOM quality was mainly influenced by soil management (organic matter amendment) whereas the quantity mainly depended on the season (heavy precipitation event). DOM humic characteristics were strongly dependent on amendment and changed with depth but was not affected by the season. Long term effect of compost organic matter was highlighted after a 7-years amendment.