The colors in the background represent the soil cover by plants (green),
and crop residues (brown). "T" indicates tillage event with a STIR value >= 0.
"P" indicates a crop protection event.
Dotted vertical lines represent sowing events, the sown crop is noted in
the lowest quarter at the right side of the line.
The values in the middle indicate C inputs into the soil system, either
by crops, cover crops or organic amendments. Negative values are withdrawls
by residue removal.
Note that large management_df can be heavy to compute and the plots may be
messy.