1. Pacific Southwest Research Station
USDA Forest Service, Research & Development
Pacific Southwest Research Station
Belowground protocol
USAID RDMA Mangrove Workshop April 23-May10, Trang, Thailand

2. Pacific Southwest Research Station

3. Pacific Southwest Research Station
Mangroves 101
Mangrove soil
% Org. Carbon
Organic Carbon content (%)
5 10 15 20
Depth(cm)
-300
-250
-200
-150
-100
-50
0
mean, 95% CI

4. Pacific Southwest Research Station

5. Pacific Southwest Research Station
USDA Forest Service, Research & Development
Pacific Southwest Research Station

6. Pacific Southwest Research Station

7. Pacific Southwest Research Station
A
F
E
D
CBA
F
E
D
CB
0-15 15-30 30-50 50-100 100-300

8. Pacific Southwest Research Station
Sediment samples should be dried to
constant weight at 60 oC as soon as
possible
Jars and sediments are weighed
to the nearest 0.1 g. Sediments
are then removed and jars
reweighed

9. Pacific Southwest Research Station
Mortar and pestle ($)
Whiley Mill ($$$)
Coffee Bean Grinder ($$$)

10. Pacific Southwest Research Station
To accurately measure soil carbon we must know:
1) Soil depth
2) Soil bulk density
3) Organic carbon concentration

11. Pacific Southwest Research Station
Soil depth

12. Pacific Southwest Research Station
Soil depth

13. Pacific Southwest Research Station
Equation for soil bulk density:
Soil bulk density (g m-3) =
Oven-dry sample mass (g)
Sample volume (m3)
Soil -Bulk density
- C content
rθ
r2
2 ( )180
π
θ - sin θ*π*r2 -
( )Sample length
collected ( )*5 *

14. Pacific Southwest Research Station
Interval Actual Interval Dry wt (g) Vol (cm3) Bulk Density (g/cm3)
0-15 5-10 52.57 74.30 0.71
15-30 20-25 52.78 74.30 0.71
30-50 42.5-47.5 60.54 74.30 0.81
50-100 70-75 47.06 74.30 0.63
>100 150-155 47.06 74.30 0.63

15. Pacific Southwest Research Station
Interval Actual Interval Dry wt (g) Vol (cm3) Bulk Density (g/cm3)
0-15 5-10 52.57 74.30 0.71
15-30 20-25 52.78 74.30 0.71
30-50 42.5-47.5 60.54 74.30 0.81
50-100 70-75 47.06 74.30 0.63
>100 150-155 47.06 74.30 0.63

16. Pacific Southwest Research Station
Soil -Bulk density
- C content
0.0003833 m3
Dry combustion method

17. Pacific Southwest Research Station
Soil Carbon (Mg ha-1) = bulk density (g cm-3) * soil
depth interval (cm) * % carbon content
FOR EACH SEDIMENT INTERVAL:

18. Pacific Southwest Research Station
Soil Carbon (Mg ha-1) = bulk density (g cm-3) * soil
depth interval (cm) * % carbon content
FOR EACH SEDIMENT INTERVAL:
Interval Actual
Interval
Bulk Density
(g/cm3)
Soil interval
(cm)
% C
content
Soil C (Mg ha-1)
0-15 5-10 0.71
15-30 20-25 0.71
30-50 42.5-47.5 0.81
50-100 70-75 0.63
>100 150-155 0.63
TOTAL
1. Total peat depth depth = 200 cm
2. 1,000,000 g = 1 Mg
3. 100,000,000 cm2 = 1 ha

19. Pacific Southwest Research Station
Soil Carbon (Mg ha-1) = bulk density (g cm-3) * soil
depth interval (cm) * % carbon content
FOR EACH SEDIMENT INTERVAL:
Interval Actual
Interval
Bulk Density
(g/cm3)
Soil interval
(cm)
% C
content
Soil C (Mg ha-1)
0-15 5-10 0.71 15 10
15-30 20-25 0.71 15 10
30-50 42.5-47.5 0.81 20 10
50-100 70-75 0.63 50 10
>100 150-155 0.63 200 10
TOTAL
1. Total peat depth depth = 200 cm
2. 1,000,000 g = 1 Mg
3. 100,000,000 cm2 = 1 ha

20. Pacific Southwest Research Station
Soil Carbon (Mg ha-1) = bulk density (g cm-3) * soil
depth interval (cm) * % carbon content
FOR EACH SEDIMENT INTERVAL:
Interval Actual
Interval
Bulk Density
(g/cm3)
Soil interval
(cm)
% C
content
Soil C (Mg ha-1)
0-15 5-10 0.71 15 10 106.14
15-30 20-25 0.71 15 10 106.56
30-50 42.5-47.5 0.81 20 10 162.97
50-100 70-75 0.63 50 10 316.71
>100 150-155 0.63 200 10 633.41
TOTAL 1325.78
1. Total peat depth depth = 200 cm
2. 1,000,000 g = 1 Mg
3. 100,000,000 cm2 = 1 ha