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…
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.
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
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