Soil Quality Impacts of Oil Development in Southern Chad

Soil Quality Impacts of Oil Development in Southern Chad

A research collaboration with Dr. Lori Leonard of Johns Hopkins University School of Public Health

Funded by a grant from the National Science Foundation

Ray WeilDept. of Environmental Science and Technology

University of Maryland

Ray WeilDept. of Environmental Science and Technology

University of Maryland

An overview of a human-soil health collaboration

20+ years of political turmoil.

February 2008:Rebels invade N’Djamena.Thousands flee fighting.

1,259,200 km2

NDjamena

Chad

Refugee camps

Doba oil field

600 km

Doba oil field

600 km

Mon

thly

rain

, mm

550mm

Doba Oil ProjectDoba Oil Project

• $3.7 billion investment.• Partial funding/oversight by World Bank• Operated by ExxonMobil (Esso Chad)• 1 billion barrels of reserves• 150,000 barrels a day production.• Oil production started in 2004.• 100,000 gross hectares.

• $3.7 billion investment.• Partial funding/oversight by World Bank• Operated by ExxonMobil (Esso Chad)• 1 billion barrels of reserves• 150,000 barrels a day production.• Oil production started in 2004.• 100,000 gross hectares.

NSF- funded project in collaboration with Dr. Lori Leonard of Johns Hopkins University School of Pubic Health.

Long term study of human health in a village affected by oil field development. Expanded to include soil health … and the connections between the two.

ITRADResearchstation

ITRADResearchstation

NgalabaVillage and farmlandsNgalabaVillage and farmlands

Town of BebedjaTown of Bebedja

Pipeline construction through village farmland in Chad.Pipeline construction through village farmland in Chad.

…leaving farmers with less cropland and less opportunity to fallow land under natural vegetation.

Oil development removed 3,200 hectares of farmers’ land-base…

Road construction through farmland

Well pad on former cropland

Power line right of way

Esso Chad agreement included compensation to community and farmers for land lostEsso Chad agreement included compensation to community and farmers for land lost

Compensation :Compensation :

...but not for degradation of remaining farmland.

...but not for degradation of remaining farmland.

Long Term Research Questions:1. How will the loss of land affect soil quality?

– Less land more intensive cropping, less or no time in natural vegetation fallow?

2. How do social parameters affect soil quality?– Distance to homestead?– Land base of farmer (see # 1)?– Household wealth (available labor, oxen, fertilizer)?

3. How will soil quality affect human health?– Mineral or vitamin deficiencies?– Calories, protein in diet?– Income to get medical care?– Diseases?

1. How will the loss of land affect soil quality?– Less land more intensive cropping, less or no

time in natural vegetation fallow?2. How do social parameters affect soil quality?

– Distance to homestead?– Land base of farmer (see # 1)?– Household wealth (available labor, oxen, fertilizer)?

3. How will soil quality affect human health?– Mineral or vitamin deficiencies?– Calories, protein in diet?– Income to get medical care?– Diseases?

Short term goals: establish baseline data prepare for long term study.

Short term goals: establish baseline data prepare for long term study.

• Select 40 households (randomly) from among those that lost some land in Ngalaba village.

• Select one field per household.• Develop a field sampling scheme. • Develop a suite of soil quality indicators. • Train Chadian team (of health workers) to

conduct soil quality assessments for long term study.

• Select 40 households (randomly) from among those that lost some land in Ngalaba village.

• Select one field per household.• Develop a field sampling scheme. • Develop a suite of soil quality indicators. • Train Chadian team (of health workers) to

conduct soil quality assessments for long term study.

Training Chadian team to conduct longitudinal study.

Field training near Ndjamena.

Setting up very simple lab in defunct research facility (ITRAD)

Minimum data set for soil quality assessment

• Assess the soils’ capacities to function -support crop productivity, mainly sorghum.

• Quantitative but simple indicators that can be tracked over years.

• Can be evaluated singly or combined into an index of SQ

• Can be measured in field or in very simple “lab”.

Soil Quality Indicators MeasuredSoil Quality Indicators Measured

• Physical (mainly in field)– Soil strength (compaction)– Soil texture (by feel)– Bulk density (core method)– Aggregate stability (slaking)– Thickness of Ap horizon– Water infiltration rate– Water holding capacity

• Chemical (mainly in lab)– Soil pH (acidity)– Available phosphorus– Electrical conductivity (EC)

• Salts• Nitrate

• Biological (mainly in field)• Active carbon (best in lab)• Presence of earthworms• Presence of termites• Termite mounds

Farmers interest and participation in soil

measurements is critical to long term project.

Phillipe

Abdon

Farmer and team making soil quality measurements

Farmer and team making soil quality measurements

2

1

3

6

7 4

5

8

9

1 •0-15 cm soil cores for fertility tests•Thickness of A horizon•Aggregate stability

23

2 • penetration resistance to 35 cm• single ring infiltration x 2• bulk density cores• “field capacity”

3 • Auger description to 90 cm

• water content to 40 cm

Termitehill

Termitehill

0.1 to 1 hectare field0.1 to 1 hectare fieldField Sampling Scheme

cores termiteSample type

1

2

3

4

5

6

7Ac

tive

C (%

of T

OC

)

a

b

5 farmers fields sampledJan. 2006

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Field I.D. (menage)

5.0

5.5

6.0

6.5

7.0

Soil

pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Field I.D. (menage)

5.0

5.5

6.0

6.5

7.0

Soil

pH

Surface soil pHwater

Example of data from ITRAD “lab” (soil pH)

0 10 20 30 40 50 60 70P1

10 20 30 40 50 60 70 80 90K

0.0 0.5 1.0 1.5ZN

0.0 0.1 0.2 0.3 0.4 0.5 0.6B

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0CU

4 6 8 10 12 14 16S04_S

Surface Soil Mehlich 3 Soil Tests

v. low low med. v. low low med. high

deficient adequate

low med.

low med. highlow med. high

phosphorus

sulfate-Scopperboron

zincpotassium

Interpretive categories based partly on Table 1.4 in Hardy, D., M. Tucker, and C. Stokes. 2007. Crop fertilization based on North Carolina soil tests. Circular No. 1. North Carolina Department of Agriculture and Consumer Services, Agronomic Division., Raleigh (NC) http://www.agr.state.nc.us/agronomi/obt14.htm

Initial samples also tested in US lab…Revealed consistently low levels of at 6 nutrients.

0.15 - 0.250.142.150.25-0.320.28PeanutPeanut

0.200.101.450.10-0.250.24SorghumSorghum

Critical SCritical SSSKCritical PCritical PPPCropCrop

3.503.63

2.5-3.01.39

Critical N

Critical N

N (LECO)

N (LECO)

Plants tell their story…from initial tissue samples analyzed in US: deficient in N, P and S.Plants tell their story…from initial tissue samples analyzed in US: deficient in N, P and S.

0 5 10 15 20 25 30 35Time after saturation, min.

10.00

13.75

17.50

21.25

25.00

28.75

32.50

36.25

40.00

Soi

l wa t

er c

onte

n t, c

m3 c

m-3

Estimation of “Field Capacity”Using capacitance sensor and hand held meter (Decagon).

Water content 30 minutes after cessation of 2nd infiltration was taken as water holding capacity.

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

ITRAD1

Field I.D. (Menage)

0.00

0.06

0.12

0.18

0.24

0.30

Soi

l wa t

er (g

g-1

)

01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

ITRAD1

Field I.D. (Menage)

0.00

0.06

0.12

0.18

0.24

0.30

Soi

l wa t

er (g

g-1

)

“Field capacity” – water content 30 min. after saturation

(Household)

Method modified from Herrick et al 2005Method modified from Herrick et al 2005

Nine dry aggregates submerged and scored on 1-6 scale:1 = >50% slaking within 5 seconds. 6 = <25% slaking after 5 minutes and 5 dips.

Nine dry aggregates submerged and scored on 1-6 scale:1 = >50% slaking within 5 seconds. 6 = <25% slaking after 5 minutes and 5 dips.

0 1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728293031323334353637383940

Field I.D. (menage)

1

2

3

4

5

6

Agg

rega

te s

lak i

ng s

core

Soils recently brought out of long bush fallowSoils recently brought out of long bush fallow

Identifying likely responsive and non-responsive soils…

0

10

20

30

40

Soi

l dep

th, c

m

0 2000 4000 6000Penetration resistance, kPa

M e n a g e 2

0

10

20

30

40

Soi

l de p

th, c

m

0 5 10 15 20 25 30 35Number of 40 cm drops, 2 kg

M e n a g e 2

10-20 cm

20-30 cm

30-40 cmSoil

dept

h (c

m)

0.00 0.05 0.10 0.15 0.20Soil water content when sampled (g g-1)

Water content at time of soil strength determination

. A for measuring soil penetration resistance. Soil Sci. Soc. Am. J. 66:1320-1324.

Using dynamic cone penetrometer of Herrick & Jones (2002).

1 2 3 4 5 6 7 8

9 10 11 12 13 14 15 16

17 18 19 20 21 22 23 24

25 26 27 28 29 30 31 32

33 34 35 36 37 38 39 40

Soil

dept

h, 0

to 4

0 cm

Mean penetration resistance (kPa) profile to 40 cm depth for each of 40 fieldsMean penetration resistance (kPa) profile to 40 cm depth for each of 40 fields

Near surface hardened plinthite (laterite) may be another factor limiting responsiveness of soils.

We are just beginning to get social and human health data to explore…

Questions?