All soils that properly classify into Land Capability Classes 2 and 3 as established by the Natural Resources Conservation Service (USDA-NRCS-Alaska, 1984).
In addition, all soils that have all of the physical characteristics of Land Capability Class 2 and 3 soils, have a 30 day or greater frost-free season, but also experience less than 1250 growing degree days. These are the soils that would classify in land capability class 4C.
Based on LAND CAPABILITY CLASSIFICATION GUIDE - ALASKA (USDA-NRCS, 1984)
Class
Soil Depth 1
-------
T-factor
Minimum AWC to
10”
-or--
Top 30”
Surface Soil (10 Inches)
Perme- ability In/hr to 30”
Drainage Class
---------
Water Table3
Flood Hazard 3, 4
Climate 5
----------
Growing Degree Days
-------
FFS
3 key crops mature
8 years in 10
--------
> 1500
--------
? 90
0-7
1.5
2-8
3
> 20“
--------
-
Any T
2
-------
3
Above plus
LS, LFS, LVFS, SI, SIC, SC; CL and SICL w>35% clay; C w/<60% clay, < 8”Peat
<35% gravel
Class 1 < .01%
0.06-20
Well Mod. Well Somewhat Poorly
--------
> 20”
None, Rare
2 key crops mature 8 years in 10
--------
> 1250
--------
? 80
0-12
3.0
1-8
4C
Meets requirements for classes 2 or 3
1 key crop matures 8 years in 10
-------
-------
? 30
Meets requirements for classes 2 or 3
Footnotes to Criteria for Soils of Local Importance
1 Depth of mineral soil to permafrost, lithic, or paralithic contact; include organic layers only for Histosols
2 Abbreviations for soil texture are:
C - Clay
CL – Silty Clay Loam
COS – Coarse Sand
COSL – Coarse Sandy Loam
FS – Fine Sand
FSL – Fine Sandy Loam
L – Loam
LCOS – Loamy Coarse Sand
LFS – Loamy Fine Sand
LS – Loamy Sand
LVFS – Loamy Very Fine Sand
S – Sand
SC – Sandy Clay
SCL – Sandy Clay Loam
SI – Silt
SIC – Silty Clay
SIL – Silt Loam
VFS – Very Fine Sand
VFSL – Very Fine Sandy Loam
3 During the growing season
4 Abbreviations for flood Hazard are:
NONE - < 1% chance
RARE – 1 – 5% chance 5 Check climate data for survey area or sub-area; note frost-free season (FFS) and growing degree-days, determine how many key crops can be grown.
