Golf course putting greens are constructed with high sand content rootzones to reduce compaction stress and maintain desirable physical characteristics. Sand is known to be low in organic matter content and fine soil particles that are important for water and nutrient retention. Little is known regarding the relationship between high-porosity, sand-based rootzones and the status and dynamics of organic matter over time in turfgrass systems. The overall objective of this study will be to improve understanding of organic matter characterization in putting greens as impacted by: (1) rootzone mix— peat amended USGA two-tier greens with and without native soil (80:20 and 80:15:5 by volume); (2) grow-in procedure—accelerated vs. controlled; (3) putting green age; and (4) soil profile depth—original rootzone vs. accumulated rootzone (caused by sand topdressing and plant material buildup; known as the mat region). Research on USGA-specification putting greens is being conducted at the University of Nebraska's John Seaton Anderson Turfgrass Research Facility near Mead, NE. Preliminary results from USGA research (1997-2005) indicate that as sand-based putting greens mature, organic matter accumulates in the rootzone and results in decreased macro-porosity and increased micro-porosity. Rootzone mix and grow-in procedure had no effect on organic matter beyond establishment year. Organic matter decreases with soil profile depth. Organic matter percent (by weight) and content (wt./per unit vol.) measure 2.4% and 0.033 g/cm³ in accumulated rootzone (i.e. mat) and 0.9% and 0.016 g/cm³ in original rootzone, respectively. Mat development is accumulating at approximately 6.5 mm annually. Sphagnum peat added to rootzone mixes at the time of construction decreased by 19-37% five to eight years following establishment and appears to stabilize at 0.8% (by weight) of rootzone composition soon after construction.