A horizon of organic material (WRB 2022 Ch 3.1.15): organic material
(oc_pct >= min_oc, default 20, Ch 3.3.13) that is at least
min_thickness cm thick (default 10). The thickness is that of the
adjoining organic layers that run from the surface, taken together. A
layer whose organic carbon is not recorded may be organic material and
leaves the answer undecided (NA) where it could change it. The
water-saturation criterion (saturated for 30 or more consecutive days, or
drained) is not read.
Arguments
- pedon
A
PedonRecord.- min_thickness
Minimum thickness (cm), default 10.
- min_oc
Minimum soil organic carbon (%) of organic material, default 20 (WRB 2022 Ch 3.3.13).
- surface_top_cm
Maximum top depth (cm) of the uppermost layer of the horizon (default 0, the soil surface).
Details
Since v0.9.313 this is the horizon only: the Histosols are keyed by
histosol(), which reads the Chapter 4 key as worded. Until then
this function was also the Histosols gate, with organic material read at
12% organic carbon and a second path of 40 cm of organic material within
the upper 80 cm.