Fig. 4.

Spreads of the observations with effects of crop rotation on the C functional groups, including alkyl, O-alkyl, aromatic, and carbonyl groups, and the ratio of alkyl to O-alkyl groups (A/O), and the ratio of alkyl to aromatic groups (A/Aroma) calculated from the 69 pairwise data collected 3 studies worldwide, where monoculture system is considered a control (i.e., 1.0). The value shown in the box indicates median, the cross mark indicates mean, and lower and upper quartiles per management