Fig. 2. Microbial biomass (MB) measured as extractable lipid phosphate (lipid-P) on (A) field-moist soils sampled in 1996 and (B) air-dried soils sampled in 1997 and 1999. Microbial biomass on air-dried soils includes those of whole soil (as the sum of MB in POM and MF), particulate organic matter (POM), and mineral fraction (MF). Each data point is a single observation. ***Both model and slope are significant at P = 0.001.