Pacific Southwest Research Station

USDA Forest Service, Research & Development Pacific Southwest Research Station

Belowground protocol

USAID RDMA Mangrove Workshop April 23-May10, Trang, Thailand

Pacific Southwest Research Station

Pacific Southwest Research Station

Mangroves 101 Mangrove soil % Org. Carbon

Organic Carbon content (%)

5 10 15 20

Dep

th (

cm

)

-300

-250

-200

-150

-100

-50

0

mean, 95% CI

Pacific Southwest Research Station

Pacific Southwest Research Station

USDA Forest Service, Research & Development Pacific Southwest Research Station

Pacific Southwest Research Station

Pacific Southwest Research Station

A

FE

D

CBA

FE

D

CB

0-15 15-30 30-50 50-100 100-300

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

Pacific Southwest Research Station

Mortar and pestle ($)

Whiley Mill ($$$)

Coffee Bean Grinder ($$$)

Pacific Southwest Research Station

To accurately measure soil carbon we must know:

1) Soil depth

2) Soil bulk density

3) Organic carbon concentration

Pacific Southwest Research Station

Soil depth

Pacific Southwest Research Station

Soil depth

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

πθ - sin θ*π*r2 -( )Sample length

collected ( )*5 *

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

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

Pacific Southwest Research Station

Soil -Bulk density

- C content

0.0003833 m3

Dry combustion method

Pacific Southwest Research Station

Soil Carbon (Mg ha-1) = bulk density (g cm-3) * soil

depth interval (cm) * % carbon content

FOR EACH SEDIMENT INTERVAL:

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

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

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