Duff (or duffage) : The layer of decomposing organic materials lying below the litter layer of freshly fallen twigs, needles and leaves and immediately above the mineral soil
Polymer Science Learning Center, University of Southern Mississippi, Glossary of Terms and Acronyms, Hattiesburg, MS, USA 2002. http://www.usm.edu/news/archives/older/style/style _guide.pdf, (Fr Sci - Amer) {456}