Short-term effect of urea on CH₄ flux under the oil palm (Elaeis guineensis) on tropical peatland in Sarawak, Malaysia

Figures & data

Table 1 Environmental characteristics of the study site

Characteristics	Mean ± standar error
Peat thickness (cm)	555
Humification value^†	H3–H5
Bulk density (g cm^−3)	0.20 ± 0.007
Mean monthly air temperature (°C)	30.9 ± 0.35
Mean monthly soil temperature at 5 cm (°C)	28.0 ± 0.17
Mean monthly soil temperature at 10 cm (°C)	27.6 ± 0.14
Annual rainfall (mm)	2,471^‡
Mean monthly water table depth (cm)	60.2 ± 2.7
Mean monthly water-filled pore space (%)	60.4 ± 2.0
Mean monthly relative humidity (%)	71.1 ± 1.47
^†Humification value was classified according to Von Post (Parent and Caron 1993). Degree of decomposition is divided into 10 levels from H1 (very fibric) to H10 (very humic).
^‡Rainfall value excludes the month of June 2003 because the rain gauge was stolen.

Figure 1  Monthly rainfall and water table at the oil palm plantation.

Figure 2  Monthly CH4 flux before and after urea application at the oil palm plantation. Data represent mean ± standard error (n = 3).

Table 2 Chemical properties of the peat soil at 0–25 cm depth

Characteristics	Mean ± standar error (n = 10)
Soil pH (1:2.5)	3.4 ± 0.04
Loss of ignition (%)	99.09
Pyrophosphate solubility index (PSI)	29.97 ± 2.1
Total C (%)	44.69 ± 1.09
Total N (%)	1.96 ± 0.07
C:N ratio	23.43 ± 1.1
NH4–N (mg kg^−1)	58.21 ± 12.9
NO3–N (mg kg^−1)	198.44 ± 101.4
CEC (cmolc kg^−1)	44.52 ± 3.1
Base saturation (%)	32.32 ± 4.5
Cation exchange capacity (CEC).

Table 3 Comparison of methane fluxes before and after urea applications to an oil palm plantation on tropical peatland

Parameter	Methane fluxes (mg C m^−2 h^−1)
Before urea application	−2.754
After urea application	1.519
Difference	4.273
Standard error	0.692
P-value	0.025

Figure 3  Interaction between soil , rainfall and pyrophosphate solubility index (PSI) on CH4 flux in the oil palm ecosystem. Note: Low (L) rainfall ≤ 200 mm; moderate (M) rainfall 200–300 mm; high (H) rainfall > 300 mm. Figures in the graph show the PSI values.

Parent , IE and Caron , J . 1993 . “ Physical properties of organic soils ” . In Soil Sampling and Methods of Analysis , Edited by: Carter , MR and Canadian Society of Soil Science . Lewis Publishers .

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