1. CARBON SEQUESTRATION IN DOUG-FIR FORESTS ON GLACIAL AND VOLCANIC SOILS IN THE PACIFIC NORTHWEST University of Washington Soils Lab A.B. Adams & Rob Harrison
Funded by DOE CENTER FOR RESEARCH ON ENHANCING CARBON SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS
CSITE

2. C SEQUESTRATION RELATED HYPOTHESES
Fertilizer increases tree biomass accumulation
Fertilizer increases soil carbon transport to deeper depths in the soil profile
Following fertilization, volcanic sites (fine-textured) soil carbon accumulation > and deeper than glacial (coarse) soil

3. FOUR (surface, A, B & C) LYSIMETERS INSTALLED IN CONTROL AND UREA FERTILIZED PLOT WITH SMC
GLACIAL SITES
Port Gamble - est. 1975; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1200 lbs/acre; thinned to 300 tpa
Cedar River - est. 1972; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1200 lbs/acre; thinned to 60% of basal area
VOLCANIC SITES
Mud Mountain - est. 1980; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1,200 lbs/acre; thinned to 300 tpa
Radio Hill - est. 1980; fertilized w/ 200 lbs/acre at 8 yrs and every 4 yrs after up to 1,200 lbs/acre; thinned to 300 tpa

4. LEACHATE COLLECTIONS FROM 4 TENSION LYSIMETERS AT ONE PLOT
A horizon least reliable
B horizon color varies
C or deep B horizon most predictable (good yield and colorless)
O horizon darkest

5. As horizons were extracted and sieved with the 25mm
screen, the components were weighed in the field. This
is material from the Bw horizon of Barneston (glacial)

6. As seen with this rocky Barneston soil, pits were dug to roughly a meter. Depths from the midpoint of each side to tops and bottoms of each horizon were measured. Means of these 4 measurements were used as water displacement levels for horizons.

7. Poulsbo soil series, Port Gamble, WA Sandy glacial with E horizon
Very thin E horizon
Deep sand
Sand very compacted at lower depths
Thin forest floor
Low understory cover
Olympic Mts. rainshadow effect

8. POULSBO SANDY LOAM
SPODIC HORIZON

10. Undetermined volcanic soil series, Mud Mt. , WA
Undetermined volcanic soil series, Mud Mt., WA. Ashy loam with no rocks
Thick forest floor
Decaying roots and tunnels present
Low bulk densities even at deepest depths

11. Winston soil series, Radio Hill, WA. Ashy loam with some rocks
Deep ashy loam
Deep lysimeter in or just above 2C glacial horizon
Some rocks
Larger forest floor
At all plots, 3mm sieve used to screen for soil to pack around porous ceramic lysimeter cups
This is Radio Hill (ashy loam).

12. COARSE FRAGMENT DISTRIBUTION FOR BARNESTON AT
CEDAR RIVER INSTALLATION
ALDERWOOD

13. COARSE FRAGMENT DISTRIBUTION FOR 3 DEPTHS
AT RADIO HILL INSTALLATION SHOWING DOMINANCE
OF THE <2mm COMPONENT

19. SUMMARY
DOC detected in epipedon decreases with depthDIC exhibits spatial and temporal variation
Texture is a factor in results, but study does not consider mineralology
Volcanic soils have lower percent of hydrophilic (labile) substances, particularly in deeper lysimeters
Fertilizer may have more effects on C dynamics with finer textured soil (volcanic)