FA. Vertisols that have, in one or

FA. Vertisols that have, in one or more horizons within 50
cm of the mineral soil surface, aquic conditions for some time
in normal years (or artificial drainage) and one or both of the
following:
1. In more than half of each pedon, either on faces of
peds or in the matrix if peds are absent, 50 percent or more
chroma of either:
a. 2 or less if redox concentrations are present; or
b. 1 or less; or
2. Enough active ferrous iron (Fe2+) to give a positive
reaction to alpha,alpha-dipyridyl at a time when the soil is
not being irrigated.