Table 1. Essential soil characteristics before crude oil contamination. (Results represent mean + standard deviation of values of the constituent cells).

Option

% by mass

Texture

pH
1:2.5

% moisture
by mass

THC
mg/kg

%

THB Count
(x 105 cfu/ml)

Sand

Silt

Clay

OC

TN

1

12.4 ± 0.3

40.1 ± 0.2

47.5 ± 0.7

SiC

4.74 ± 0.20

13 ± 1

84.1 ± 5.0

0.19 ± 0.02

0.38 ± 0.03

3.3 ± 0.14

2

15.3 ± 0.4

45.2 ± 0.2

39.5 ± 0.6

SiCL

4.73 ± 0.30

17 ± 1

46.7± 3.0

0.18 ± 0.01

0.36 ± 0.02

4.3 ± 0.15

3

11.3 ± 0.5

39.2 ± 0.2

49.5 ± 0.4

SiC

4.61 ± 0.10

12 ± 2

78.2 ± 10.2

0.28 ± 0.02

0.68 ± 0.03

5.2 ± 0.20

4

16.1 ± 0.5

45.1 ± 0.2

38.8 ± 0.5

SiCL

4.45 ± 0.20

13 ± 1

25.9 ± 4.0

0.20 ± 0.02

0.40 ± 0.03

3.9 ± 0.20

5

14.4 ± 0.6

46.1 ± 0.4

39.5 ± 0.5

SiCL

4.54 ± 0.20

14 ± 1

25.3 ± 5.4

0.22 ± 0.03

0.61 ± 0.05

4.1 ± 0.10

6

10.9 ± 0.3

41.0 ± 0.2

48.1 ± 0.4

SiC

4.71 ± 0.25

13 ± 2

25.4 ± 8.1

0.19 ± 0.02

0.34 ± 0.03

4.7 ± 0.05

7

18.1 ± 0.4

45.1 ± 0.3

36.8 ± 0.1

SiCL

4.66 ± 0.25

16 ± 1

31.2 ± 4.5

0.26 ± 0.01

0.56 ± 0.01

4.9 ± 0.25

Option 1: Different levels of fertilizer application.
Option 2: Variation in soil oxygen levels through various rates of tillage.
Option 3: Different levels of water application.
Option 4: Combination of different levels of tillage, water and fertilizer application.
Option 5: Biopile treatment.
Option 6: Phytoremediation treatment (using maize and elephant grass).
Option 7: Control, without remediation treatment.
OC: Organic carbon.
TN: Total nitrogen.
THB: Total heterotrophic bacteria.
cfu/ml: Colony forming unit per millilitre.

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