Average soil formation rate:
Geologic or natural erosion rate:
or  ~ 1 ton per acre
USDA tolerable soil loss per year:
or 5 tons per acre !!
~.25 mm per year = 2.5 Mg ha-1
11 Mg ha-1  !!
0.03 mm per year  or ~ 0.3 Mg ha-1
or  ~>0.1 ton per acre !!