Incorporation of fine root detritus into forest soil organic matter

One of the principal inputs organic matter to forest soils is turnover tree fine roots, but process decomposition root litter and its conversion into stable soil (SOM) has received limited study. We labeled roots sugar maple (Acer saccharum Marsh.) with 13C traced label for 7 years four contrasting improve understanding this process. After we recovered an average 8.9% label, about two-thirds as coarse particulate one-third in microaggregates on silt clay particles. No differences recovery were detected between 1–2 3–4 order roots. Most (53–250 µm, 58%) was occluded within macroaggregates, fraction increased significantly from year 2 7, illustrating role detritus formation microaggregates. This most pronounced A horizon a higher pH (pH = 5.5) high iron oxide content. Conversely, lowest observed acidic, fine-textured Inceptisol (Cambisol—World Reference Base). estimate that annual input relatively fractions SOM represents 14% total accumulation these fractions; thus, our results support recent evidence only moderate contributor acid temperate soils.