Fig. 1. Average N (left black bars) and amino sugar concentration (right lined bars) in the surface soil (0–5 cm) of the prairie, Conservation Reserve Program (CRP) and cropland fields under study. Different letters (a–b, c–e) indicate significant difference among land-use systems at the P < 0.05 level of probability using ANOVA and the respective relative concentrations (normalized to N or the amino sugar content of the prairie) as input parameters.