Fig. 7. Relationship of the amount of microbial biomass (MB) in particulate organic matter (POM) relative to mineral fraction (MF) to the amount of humic substances in POM relative to MF. Soils are air-dried and from greens sampled in 1997 and 1999. HA-C, humic acid carbon; FA-C, fulvic acid carbon. ***Both model and slope are significant at P = 0.001.