64 
100 
80 
60 
40 
CEC, meq(l00g)7! by Na OAc 
20 
4 4 
4 ——— 1 4 1 — 1 1 
O 2onl 40. Vico" Weer N00 
CEC, meq (I00g)! by NH4 OAc 
Fig. 1. Relationship of Na exchange capacity to 
NH 4 exchange capacity. 
T T a as = T 
goo} * Surface soils OS 
° Subsoils 
[o) 
Is 
E 
=i 
600 
2 
= 
Oo 
=) 
400 
Oo 
S) 
To) 
iS 
© 200 
uJ 
1 = a to 4 i 
O 20 40 60 
Organic Matter, % 
Fig. 2. Relationship of electrical conductivity 
of (1:7 soil:water) soil extracts to percent soil 
organic matter. 
of the area—shallow active layer, much organic 
matter, calcareous, pH proportional to carbon- 
ates, appreciable soluble salts, etc. It was not 
possible to accurately determine exchangeable 
cations because of the solubility of carbonates, 
which gave a sum of exchangeable cations sever- 
al times as large as cation exchange capacity, 
analytically correct but obviously impossible. 
Cation exchange capacity was proportional to 
the amount of organic matter in the soil. 
Sodium exchange capacity was, in nearly 
every instance, a little larger than ammonia ex- 
change capacity; in other words, all soils have an 
ammonia fixing capacity (Fig. 1). It should be 
noted that sodium exchange capacity determina- 
tions were made at pH 8.2, and ammonia ex- 
change capacities were made at pH 7. The pH 
dependent exchange capacity (pH 8.2 - 7) was 
found to be 1.2 to 2 meq (100 g)"'. Subtracting 
this value from the calculated ammonia fixing 
capacity showed that the typical soil of the area 
has an ammonia fixing capacity of about 7 meq 
(100 g)"', and that this value was independent 
of soil organic matter content. 
The relationship of electrical conductivity of 
soil solutions to organic matter content of the 
same soils is shown in Fig. 2. Electrical 
conductivity is a measure of the amount of 
readily soluble salts present in a soil. In the 
Prudhoe Bay area, this value is dependent on the 
organic matter contents of the soil. Soils high in 
Organic matter are usually found on the lower 
relief positions in the relatively low, undulating 
Prudhoe Bay landscape. Often these soils have 
water standing on their surface during much of 
the summer. There are two possible explanations 
for the accumulation of soluble salts in the 
low-lying organic soils. 
1. The water standing on these soils forms a 
good evaporation surface, and soluble salts are 
concentrated by evaporation. 
2. Much of the water found at lower eleva- 
tions represents runoff (either surface or sub- 
surface) from upland surfaces. This runoff water 
has been in actual physical contact with the soil 
for a longer period of time than the upland 
waters. One seldom finds equilibrium conditions 
in asoil since, with the comparatively short times 
involved, concentration of ions in the soil seldom 
reaches equilibrium solubilities. However, water 
